Stop assuming no-debug-info functions return int

The fact that GDB defaults to assuming that functions return int, when
it has no debug info for the function has been a recurring source of
user confusion.  Recently this came up on the errno pretty printer
discussions.  Shortly after, it came up again on IRC, with someone
wondering why does getenv() in GDB return a negative int:

  (gdb) p getenv("PATH")
  $1 = -6185

This question (with s/getenv/random-other-C-runtime-function) is a FAQ
on IRC.

The reason for the above is:

 (gdb) p getenv
 $2 = {<text variable, no debug info>} 0x7ffff7751d80 <getenv>
 (gdb) ptype getenv
 type = int ()

... which means that GDB truncated the 64-bit pointer that is actually
returned from getent to 32-bit, and then sign-extended it:

 (gdb) p /x -6185
 $6 = 0xffffe7d7

The workaround is to cast the function to the right type, like:

 (gdb) p ((char *(*) (const char *)) getenv) ("PATH")
 $3 = 0x7fffffffe7d7 "/usr/local/bin:/"...

IMO, we should do better than this.

I see the "assume-int" issue the same way I see printing bogus values
for optimized-out variables instead of "<optimized out>" -- I'd much
rather that the debugger tells me "I don't know" and tells me how to
fix it than showing me bogus misleading results, making me go around
tilting at windmills.

If GDB prints a signed integer when you're expecting a pointer or
aggregate, you at least have some sense that something is off, but
consider the case of the function actually returning a 64-bit integer.
For example, compile this without debug info:

 unsigned long long
 function ()
 {
   return 0x7fffffffffffffff;
 }

Currently, with pristine GDB, you get:

 (gdb) p function ()
 $1 = -1                      # incorrect
 (gdb) p /x function ()
 $2 = 0xffffffff              # incorrect

maybe after spending a few hours debugging you suspect something is
wrong with that -1, and do:

 (gdb) ptype function
 type = int ()

and maybe, just maybe, you realize that the function actually returns
unsigned long long.  And you try to fix it with:

(gdb) p /x (unsigned long long) function ()
 $3 = 0xffffffffffffffff      # incorrect

... which still produces the wrong result, because GDB simply applied
int to unsigned long long conversion.  Meaning, it sign-extended the
integer that it extracted from the return of the function, to 64-bits.

and then maybe, after asking around on IRC, you realize you have to
cast the function to a pointer of the right type, and call that.  It
won't be easy, but after a few missteps, you'll get to it:

.....  (gdb) p /x ((unsigned long long(*) ()) function) ()
 $666 = 0x7fffffffffffffff             # finally! :-)


So to improve on the user experience, this patch does the following
(interrelated) things:

 - makes no-debug-info functions no longer default to "int" as return
   type.  Instead, they're left with NULL/"<unknown return type>"
   return type.

    (gdb) ptype getenv
    type = <unknown return type> ()

 - makes calling a function with unknown return type an error.

    (gdb) p getenv ("PATH")
    'getenv' has unknown return type; cast the call to its declared return type

 - and then to make it easier to call the function, makes it possible
   to _only_ cast the return of the function to the right type,
   instead of having to cast the function to a function pointer:

    (gdb) p (char *) getenv ("PATH")                      # now Just Works
    $3 = 0x7fffffffe7d7 "/usr/local/bin:/"...

    (gdb) p ((char *(*) (const char *)) getenv) ("PATH")  # continues working
    $4 = 0x7fffffffe7d7 "/usr/local/bin:/"...

   I.e., it makes GDB default the function's return type to the type
   of the cast, and the function's parameters to the type of the
   arguments passed down.

After this patch, here's what you'll get for the "unsigned long long"
example above:

 (gdb) p function ()
 'function' has unknown return type; cast the call to its declared return type
 (gdb) p /x (unsigned long long) function ()
 $4 = 0x7fffffffffffffff     # correct!

Note that while with "print" GDB shows the name of the function that
has the problem:

  (gdb) p getenv ("PATH")
  'getenv' has unknown return type; cast the call to its declared return type

which can by handy in more complicated expressions, "ptype" does not:

  (gdb) ptype getenv ("PATH")
  function has unknown return type; cast the call to its declared return type

This will be fixed in the next patch.

gdb/ChangeLog:
2017-09-04  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
	TYPE_GNU_IFUNC specially here.  Throw error if return type is
	unknown.
	* ada-typeprint.c (print_func_type): Handle functions with unknown
	return type.
	* c-typeprint.c (c_type_print_base): Handle functions and methods
	with unknown return type.
	* compile/compile-c-symbols.c (convert_symbol_bmsym)
	<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
	* compile/compile-c-types.c: Include "objfiles.h".
	(convert_func): For functions with unknown return type, warn and
	default to int.
	* compile/compile-object-run.c (compile_object_run): Adjust call
	to call_function_by_hand_dummy.
	* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
	call_function_by_hand.
	* eval.c (evaluate_subexp_standard): Adjust calls to
	call_function_by_hand.  Handle functions and methods with unknown
	return type.  Pass expect_type to call_function_by_hand.
	* f-typeprint.c (f_type_print_base): Handle functions with unknown
	return type.
	* gcore.c (call_target_sbrk): Adjust call to
	call_function_by_hand.
	* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
	return type instead of int.  Make nodebug_text_gnu_ifunc_symbol be
	an integer address type instead of nodebug.
	* guile/scm-value.c (gdbscm_value_call): Adjust call to
	call_function_by_hand.
	* infcall.c (error_call_unknown_return_type): New function.
	(call_function_by_hand): New "default_return_type" parameter.
	Pass it down.
	(call_function_by_hand_dummy): New "default_return_type"
	parameter.  Use it instead of defaulting to int.  If there's no
	default and the return type is unknown, throw an error.  If
	there's a default return type, and the called function has no
	debug info, then assume the function is prototyped.
	* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
	New "default_return_type" parameter.
	(error_call_unknown_return_type): New declaration.
	* linux-fork.c (call_lseek): Cast return type of lseek.
	(inferior_call_waitpid, checkpoint_command): Adjust calls to
	call_function_by_hand.
	* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
	calls to call_function_by_hand.
	* m2-typeprint.c (m2_procedure): Handle functions with unknown
	return type.
	* objc-lang.c (lookup_objc_class, lookup_child_selector)
	(value_nsstring, print_object_command): Adjust calls to
	call_function_by_hand.
	* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
	functions with unknown return type.
	(pascal_type_print_func_varspec_suffix): New function.
	(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
	TYPE_CODE_METHOD>: Use it.
	* python/py-value.c (valpy_call): Adjust call to
	call_function_by_hand.
	* rust-lang.c (rust_evaluate_funcall): Adjust call to
	call_function_by_hand.
	* valarith.c (value_x_binop, value_x_unop): Adjust calls to
	call_function_by_hand.
	* valops.c (value_allocate_space_in_inferior): Adjust call to
	call_function_by_hand.
	* typeprint.c (type_print_unknown_return_type): New function.
	* typeprint.h (type_print_unknown_return_type): New declaration.

gdb/testsuite/ChangeLog:
2017-09-04  Pedro Alves  <palves@redhat.com>

	* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
	return type of munmap in infcall.
	* gdb.base/break-probes.exp: Cast return type of foo in infcall.
	* gdb.base/checkpoint.exp: Simplify using for loop.  Cast return
	type of ftell in infcall.
	* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
	type of getpid in infcall.
	* gdb.base/infcall-exec.exp: Cast return type of execlp in
	infcall.
	* gdb.base/info-os.exp: Cast return type of getpid in infcall.
	Bail on failure to extract the pid.
	* gdb.base/nodebug.c: #include <stdint.h>.
	(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
	New functions.
	* gdb.base/nodebug.exp (test_call_promotion): New procedure.
	Change expected output of print/whatis/ptype with functions with
	no debug info.  Test all supported languages.  Call
	test_call_promotion.
	* gdb.compile/compile.exp: Adjust expected output to expect
	warning.
	* gdb.threads/siginfo-threads.exp: Likewise.

37 files changed, 475 insertions, 154 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d1fe7ca8758..85cd3f90399 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,72 @@
 2017-09-04  Pedro Alves  <palves@redhat.com>
 
+	* ada-lang.c (ada_evaluate_subexp) <TYPE_CODE_FUNC>: Don't handle
+	TYPE_GNU_IFUNC specially here.  Throw error if return type is
+	unknown.
+	* ada-typeprint.c (print_func_type): Handle functions with unknown
+	return type.
+	* c-typeprint.c (c_type_print_base): Handle functions and methods
+	with unknown return type.
+	* compile/compile-c-symbols.c (convert_symbol_bmsym)
+	<mst_text_gnu_ifunc>: Use nodebug_text_gnu_ifunc_symbol.
+	* compile/compile-c-types.c: Include "objfiles.h".
+	(convert_func): For functions with unknown return type, warn and
+	default to int.
+	* compile/compile-object-run.c (compile_object_run): Adjust call
+	to call_function_by_hand_dummy.
+	* elfread.c (elf_gnu_ifunc_resolve_addr): Adjust call to
+	call_function_by_hand.
+	* eval.c (evaluate_subexp_standard): Adjust calls to
+	call_function_by_hand.  Handle functions and methods with unknown
+	return type.  Pass expect_type to call_function_by_hand.
+	* f-typeprint.c (f_type_print_base): Handle functions with unknown
+	return type.
+	* gcore.c (call_target_sbrk): Adjust call to
+	call_function_by_hand.
+	* gdbtypes.c (objfile_type): Leave nodebug text symbol with NULL
+	return type instead of int.  Make nodebug_text_gnu_ifunc_symbol be
+	an integer address type instead of nodebug.
+	* guile/scm-value.c (gdbscm_value_call): Adjust call to
+	call_function_by_hand.
+	* infcall.c (error_call_unknown_return_type): New function.
+	(call_function_by_hand): New "default_return_type" parameter.
+	Pass it down.
+	(call_function_by_hand_dummy): New "default_return_type"
+	parameter.  Use it instead of defaulting to int.  If there's no
+	default and the return type is unknown, throw an error.  If
+	there's a default return type, and the called function has no
+	debug info, then assume the function is prototyped.
+	* infcall.h (call_function_by_hand, call_function_by_hand_dummy):
+	New "default_return_type" parameter.
+	(error_call_unknown_return_type): New declaration.
+	* linux-fork.c (call_lseek): Cast return type of lseek.
+	(inferior_call_waitpid, checkpoint_command): Adjust calls to
+	call_function_by_hand.
+	* linux-tdep.c (linux_infcall_mmap, linux_infcall_munmap): Adjust
+	calls to call_function_by_hand.
+	* m2-typeprint.c (m2_procedure): Handle functions with unknown
+	return type.
+	* objc-lang.c (lookup_objc_class, lookup_child_selector)
+	(value_nsstring, print_object_command): Adjust calls to
+	call_function_by_hand.
+	* p-typeprint.c (pascal_type_print_varspec_prefix): Handle
+	functions with unknown return type.
+	(pascal_type_print_func_varspec_suffix): New function.
+	(pascal_type_print_varspec_suffix) <TYPE_CODE_FUNC,
+	TYPE_CODE_METHOD>: Use it.
+	* python/py-value.c (valpy_call): Adjust call to
+	call_function_by_hand.
+	* rust-lang.c (rust_evaluate_funcall): Adjust call to
+	call_function_by_hand.
+	* valarith.c (value_x_binop, value_x_unop): Adjust calls to
+	call_function_by_hand.
+	* valops.c (value_allocate_space_in_inferior): Adjust call to
+	call_function_by_hand.
+	* typeprint.c (type_print_unknown_return_type): New function.
+	* typeprint.h (type_print_unknown_return_type): New declaration.
+
+2017-09-04  Pedro Alves  <palves@redhat.com>
+
 	* gdbtypes.c (lookup_function_type_with_arguments): Mark function
 	types with more than one parameter as prototyped.
 
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index b4e193ca802..519dfb12924 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -10789,13 +10789,11 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
         case TYPE_CODE_FUNC:
           if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	    {
-	      struct type *rtype = TYPE_TARGET_TYPE (type);
-
-	      if (TYPE_GNU_IFUNC (type))
-		return allocate_value (TYPE_TARGET_TYPE (rtype));
-	      return allocate_value (rtype);
+	      if (TYPE_TARGET_TYPE (type) == NULL)
+		error_call_unknown_return_type (NULL);
+	      return allocate_value (TYPE_TARGET_TYPE (type));
 	    }
-          return call_function_by_hand (argvec[0], nargs, argvec + 1);
+	  return call_function_by_hand (argvec[0], NULL, nargs, argvec + 1);
 	case TYPE_CODE_INTERNAL_FUNCTION:
 	  if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	    /* We don't know anything about what the internal
diff --git a/gdb/ada-typeprint.c b/gdb/ada-typeprint.c
index 83925134260..2224bb3d79f 100644
--- a/gdb/ada-typeprint.c
+++ b/gdb/ada-typeprint.c
@@ -773,7 +773,8 @@ print_func_type (struct type *type, struct ui_file *stream, const char *name,
 {
   int i, len = TYPE_NFIELDS (type);
 
-  if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_VOID)
+  if (TYPE_TARGET_TYPE (type) != NULL
+      && TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_VOID)
     fprintf_filtered (stream, "procedure");
   else
     fprintf_filtered (stream, "function");
@@ -798,7 +799,9 @@ print_func_type (struct type *type, struct ui_file *stream, const char *name,
       fprintf_filtered (stream, ")");
     }
 
-  if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
+  if (TYPE_TARGET_TYPE (type) == NULL)
+    fprintf_filtered (stream, " return <unknown return type>");
+  else if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
     {
       fprintf_filtered (stream, " return ");
       ada_print_type (TYPE_TARGET_TYPE (type), "", stream, 0, 0, flags);
diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c
index 890888bd4f9..f752300403e 100644
--- a/gdb/c-typeprint.c
+++ b/gdb/c-typeprint.c
@@ -893,13 +893,19 @@ c_type_print_base (struct type *type, struct ui_file *stream,
       fprintf_filtered (stream, _("<unnamed typedef>"));
       break;
 
+    case TYPE_CODE_FUNC:
+    case TYPE_CODE_METHOD:
+      if (TYPE_TARGET_TYPE (type) == NULL)
+	type_print_unknown_return_type (stream);
+      else
+	c_type_print_base (TYPE_TARGET_TYPE (type),
+			   stream, show, level, flags);
+      break;
     case TYPE_CODE_ARRAY:
     case TYPE_CODE_PTR:
     case TYPE_CODE_MEMBERPTR:
     case TYPE_CODE_REF:
     case TYPE_CODE_RVALUE_REF:
-    case TYPE_CODE_FUNC:
-    case TYPE_CODE_METHOD:
     case TYPE_CODE_METHODPTR:
       c_type_print_base (TYPE_TARGET_TYPE (type),
 			 stream, show, level, flags);
diff --git a/gdb/compile/compile-c-symbols.c b/gdb/compile/compile-c-symbols.c
index 1cdea852ea3..ee21cf1515a 100644
--- a/gdb/compile/compile-c-symbols.c
+++ b/gdb/compile/compile-c-symbols.c
@@ -376,9 +376,7 @@ convert_symbol_bmsym (struct compile_c_instance *context,
       break;
 
     case mst_text_gnu_ifunc:
-      /* nodebug_text_gnu_ifunc_symbol would cause:
-	 function return type cannot be function  */
-      type = objfile_type (objfile)->nodebug_text_symbol;
+      type = objfile_type (objfile)->nodebug_text_gnu_ifunc_symbol;
       kind = GCC_C_SYMBOL_FUNCTION;
       addr = gnu_ifunc_resolve_addr (target_gdbarch (), addr);
       break;
diff --git a/gdb/compile/compile-c-types.c b/gdb/compile/compile-c-types.c
index dc6391c8b5b..2bfa72d2b8c 100644
--- a/gdb/compile/compile-c-types.c
+++ b/gdb/compile/compile-c-types.c
@@ -21,6 +21,8 @@
 #include "defs.h"
 #include "gdbtypes.h"
 #include "compile-internal.h"
+#include "objfiles.h"
+
 /* An object that maps a gdb type to a gcc type.  */
 
 struct type_map_instance
@@ -233,9 +235,25 @@ convert_func (struct compile_c_instance *context, struct type *type)
   struct gcc_type_array array;
   int is_varargs = TYPE_VARARGS (type) || !TYPE_PROTOTYPED (type);
 
+  struct type *target_type = TYPE_TARGET_TYPE (type);
+
+  /* Functions with no debug info have no return type.  Ideally we'd
+     want to fallback to the type of the cast just before the
+     function, like GDB's built-in expression parser, but we don't
+     have access to that type here.  For now, fallback to int, like
+     GDB's parser used to do.  */
+  if (target_type == NULL)
+    {
+      if (TYPE_OBJFILE_OWNED (type))
+	target_type = objfile_type (TYPE_OWNER (type).objfile)->builtin_int;
+      else
+	target_type = builtin_type (TYPE_OWNER (type).gdbarch)->builtin_int;
+      warning (_("function has unknown return type; assuming int"));
+    }
+
   /* This approach means we can't make self-referential function
      types.  Those are impossible in C, though.  */
-  return_type = convert_type (context, TYPE_TARGET_TYPE (type));
+  return_type = convert_type (context, target_type);
 
   array.n_elements = TYPE_NFIELDS (type);
   array.elements = XNEWVEC (gcc_type, TYPE_NFIELDS (type));
diff --git a/gdb/compile/compile-object-run.c b/gdb/compile/compile-object-run.c
index de5fa163020..43da59fc791 100644
--- a/gdb/compile/compile-object-run.c
+++ b/gdb/compile/compile-object-run.c
@@ -172,7 +172,8 @@ compile_object_run (struct compile_module *module)
 	  ++current_arg;
 	}
       gdb_assert (current_arg == TYPE_NFIELDS (func_type));
-      call_function_by_hand_dummy (func_val, TYPE_NFIELDS (func_type), vargs,
+      call_function_by_hand_dummy (func_val,
+				   NULL, TYPE_NFIELDS (func_type), vargs,
 				   do_module_cleanup, data);
     }
   CATCH (ex, RETURN_MASK_ERROR)
diff --git a/gdb/elfread.c b/gdb/elfread.c
index cad7aa8647f..ae84e43837c 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -877,7 +877,7 @@ elf_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc)
   target_auxv_search (&current_target, AT_HWCAP, &hwcap);
   hwcap_val = value_from_longest (builtin_type (gdbarch)
 				  ->builtin_unsigned_long, hwcap);
-  address_val = call_function_by_hand (function, 1, &hwcap_val);
+  address_val = call_function_by_hand (function, NULL, 1, &hwcap_val);
   address = value_as_address (address_val);
   address = gdbarch_convert_from_func_ptr_addr (gdbarch, address,
 						&current_target);
diff --git a/gdb/eval.c b/gdb/eval.c
index 80dfb2e38d8..1ec67513af2 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -1147,12 +1147,12 @@ evaluate_subexp_standard (struct type *expect_type,
 	argvec[3] = value_from_longest (long_type, selector);
 	argvec[4] = 0;
 
-	ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	ret = call_function_by_hand (argvec[0], NULL, 3, argvec + 1);
 	if (gnu_runtime)
 	  {
 	    /* Function objc_msg_lookup returns a pointer.  */
 	    argvec[0] = ret;
-	    ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	    ret = call_function_by_hand (argvec[0], NULL, 3, argvec + 1);
 	  }
 	if (value_as_long (ret) == 0)
 	  error (_("Target does not respond to this message selector."));
@@ -1169,11 +1169,11 @@ evaluate_subexp_standard (struct type *expect_type,
 	argvec[3] = value_from_longest (long_type, selector);
 	argvec[4] = 0;
 
-	ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	ret = call_function_by_hand (argvec[0], NULL, 3, argvec + 1);
 	if (gnu_runtime)
 	  {
 	    argvec[0] = ret;
-	    ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	    ret = call_function_by_hand (argvec[0], NULL, 3, argvec + 1);
 	  }
 
 	/* ret should now be the selector.  */
@@ -1315,10 +1315,10 @@ evaluate_subexp_standard (struct type *expect_type,
 	    deprecated_set_value_type (argvec[0],
 				       lookup_pointer_type (lookup_function_type (value_type (argvec[0]))));
 	    argvec[0]
-	      = call_function_by_hand (argvec[0], nargs + 2, argvec + 1);
+	      = call_function_by_hand (argvec[0], NULL, nargs + 2, argvec + 1);
 	  }
 
-	ret = call_function_by_hand (argvec[0], nargs + 2, argvec + 1);
+	ret = call_function_by_hand (argvec[0], NULL, nargs + 2, argvec + 1);
 	return ret;
       }
       break;
@@ -1705,12 +1705,9 @@ evaluate_subexp_standard (struct type *expect_type,
 	error (_("Cannot evaluate function -- may be inlined"));
       if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	{
-	  /* If the return type doesn't look like a function type, call an
-	     error.  This can happen if somebody tries to turn a variable into
-	     a function call.  This is here because people often want to
-	     call, eg, strcmp, which gdb doesn't know is a function.  If
-	     gdb isn't asked for it's opinion (ie. through "whatis"),
-	     it won't offer it.  */
+	  /* If the return type doesn't look like a function type,
+	     call an error.  This can happen if somebody tries to turn
+	     a variable into a function call.  */
 
 	  struct type *ftype = value_type (argvec[0]);
 
@@ -1731,10 +1728,19 @@ evaluate_subexp_standard (struct type *expect_type,
 		error (_("Xmethod is missing return type."));
 	      return value_zero (return_type, not_lval);
 	    }
-	  else if (TYPE_GNU_IFUNC (ftype))
-	    return allocate_value (TYPE_TARGET_TYPE (TYPE_TARGET_TYPE (ftype)));
-	  else if (TYPE_TARGET_TYPE (ftype))
-	    return allocate_value (TYPE_TARGET_TYPE (ftype));
+	  else if (TYPE_CODE (ftype) == TYPE_CODE_FUNC
+		   || TYPE_CODE (ftype) == TYPE_CODE_METHOD)
+	    {
+	      struct type *return_type = TYPE_TARGET_TYPE (ftype);
+
+	      if (return_type == NULL)
+		return_type = expect_type;
+
+	      if (return_type == NULL)
+		error_call_unknown_return_type (NULL);
+
+	      return allocate_value (return_type);
+	    }
 	  else
 	    error (_("Expression of type other than "
 		     "\"Function returning ...\" used as function"));
@@ -1747,7 +1753,8 @@ evaluate_subexp_standard (struct type *expect_type,
 	case TYPE_CODE_XMETHOD:
 	  return call_xmethod (argvec[0], nargs, argvec + 1);
 	default:
-	  return call_function_by_hand (argvec[0], nargs, argvec + 1);
+	  return call_function_by_hand (argvec[0],
+					expect_type, nargs, argvec + 1);
 	}
       /* pai: FIXME save value from call_function_by_hand, then adjust
 	 pc by adjust_fn_pc if +ve.  */
diff --git a/gdb/f-typeprint.c b/gdb/f-typeprint.c
index 7dbe093a7fc..2a858aab171 100644
--- a/gdb/f-typeprint.c
+++ b/gdb/f-typeprint.c
@@ -304,9 +304,14 @@ f_type_print_base (struct type *type, struct ui_file *stream, int show,
       break;
 
     case TYPE_CODE_ARRAY:
-    case TYPE_CODE_FUNC:
       f_type_print_base (TYPE_TARGET_TYPE (type), stream, show, level);
       break;
+    case TYPE_CODE_FUNC:
+      if (TYPE_TARGET_TYPE (type) == NULL)
+	type_print_unknown_return_type (stream);
+      else
+	f_type_print_base (TYPE_TARGET_TYPE (type), stream, show, level);
+      break;
 
     case TYPE_CODE_PTR:
       fprintf_filtered (stream, "PTR TO -> ( ");
diff --git a/gdb/gcore.c b/gdb/gcore.c
index 50aff2ce520..07c1997bfdf 100644
--- a/gdb/gcore.c
+++ b/gdb/gcore.c
@@ -303,7 +303,7 @@ call_target_sbrk (int sbrk_arg)
   target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 
 					sbrk_arg);
   gdb_assert (target_sbrk_arg);
-  ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg);
+  ret = call_function_by_hand (sbrk_fn, NULL, 1, &target_sbrk_arg);
   if (ret == NULL)
     return (bfd_vma) 0;
 
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index ceb4f0ca2aa..a22f0ca21e8 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -5312,13 +5312,13 @@ objfile_type (struct objfile *objfile)
   objfile_type->nodebug_text_symbol
     = init_type (objfile, TYPE_CODE_FUNC, 1,
 		 "<text variable, no debug info>");
-  TYPE_TARGET_TYPE (objfile_type->nodebug_text_symbol)
-    = objfile_type->builtin_int;
   objfile_type->nodebug_text_gnu_ifunc_symbol
     = init_type (objfile, TYPE_CODE_FUNC, 1,
 		 "<text gnu-indirect-function variable, no debug info>");
+  /* Ifunc resolvers return a function address.  */
   TYPE_TARGET_TYPE (objfile_type->nodebug_text_gnu_ifunc_symbol)
-    = objfile_type->nodebug_text_symbol;
+    = init_integer_type (objfile, gdbarch_addr_bit (gdbarch), 1,
+			 "__IFUNC_RESOLVER_RET");
   TYPE_GNU_IFUNC (objfile_type->nodebug_text_gnu_ifunc_symbol) = 1;
   objfile_type->nodebug_got_plt_symbol
     = init_pointer_type (objfile, gdbarch_addr_bit (gdbarch),
diff --git a/gdb/guile/scm-value.c b/gdb/guile/scm-value.c
index f63103227ce..0dc66302ed3 100644
--- a/gdb/guile/scm-value.c
+++ b/gdb/guile/scm-value.c
@@ -864,7 +864,7 @@ gdbscm_value_call (SCM self, SCM args)
       struct cleanup *cleanup = make_cleanup_value_free_to_mark (mark);
       struct value *return_value;
 
-      return_value = call_function_by_hand (function, args_count, vargs);
+      return_value = call_function_by_hand (function, NULL, args_count, vargs);
       result = vlscm_scm_from_value (return_value);
       do_cleanups (cleanup);
     }
diff --git a/gdb/infcall.c b/gdb/infcall.c
index 9e434a9df41..cd3eedfeeb7 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -340,6 +340,20 @@ push_dummy_code (struct gdbarch *gdbarch,
 				  regcache);
 }
 
+/* See infcall.h.  */
+
+void
+error_call_unknown_return_type (const char *func_name)
+{
+  if (func_name != NULL)
+    error (_("'%s' has unknown return type; "
+	     "cast the call to its declared return type"),
+	   func_name);
+  else
+    error (_("function has unknown return type; "
+	     "cast the call to its declared return type"));
+}
+
 /* Fetch the name of the function at FUNADDR.
    This is used in printing an error message for call_function_by_hand.
    BUF is used to print FUNADDR in hex if the function name cannot be
@@ -673,9 +687,12 @@ cleanup_delete_std_terminate_breakpoint (void *ignore)
 /* See infcall.h.  */
 
 struct value *
-call_function_by_hand (struct value *function, int nargs, struct value **args)
+call_function_by_hand (struct value *function,
+		       type *default_return_type,
+		       int nargs, struct value **args)
 {
-  return call_function_by_hand_dummy (function, nargs, args, NULL, NULL);
+  return call_function_by_hand_dummy (function, default_return_type,
+				      nargs, args, NULL, NULL);
 }
 
 /* All this stuff with a dummy frame may seem unnecessarily complicated
@@ -698,6 +715,7 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
 
 struct value *
 call_function_by_hand_dummy (struct value *function,
+			     type *default_return_type,
 			     int nargs, struct value **args,
 			     dummy_frame_dtor_ftype *dummy_dtor,
 			     void *dummy_dtor_data)
@@ -850,8 +868,16 @@ call_function_by_hand_dummy (struct value *function,
   }
 
   funaddr = find_function_addr (function, &values_type);
-  if (!values_type)
-    values_type = builtin_type (gdbarch)->builtin_int;
+  if (values_type == NULL)
+    values_type = default_return_type;
+  if (values_type == NULL)
+    {
+      const char *name = get_function_name (funaddr,
+					    name_buf, sizeof (name_buf));
+      error (_("'%s' has unknown return type; "
+	       "cast the call to its declared return type"),
+	     name);
+    }
 
   values_type = check_typedef (values_type);
 
@@ -955,6 +981,21 @@ call_function_by_hand_dummy (struct value *function,
 	   prototyped.  Can we respect TYPE_VARARGS?  Probably not.  */
 	if (TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 	  prototyped = 1;
+	if (TYPE_TARGET_TYPE (ftype) == NULL && TYPE_NFIELDS (ftype) == 0
+	    && default_return_type != NULL)
+	  {
+	    /* Calling a no-debug function with the return type
+	       explicitly cast.  Assume the function is prototyped,
+	       with a prototype matching the types of the arguments.
+	       E.g., with:
+		 float mult (float v1, float v2) { return v1 * v2; }
+	       This:
+		 (gdb) p (float) mult (2.0f, 3.0f)
+	       Is a simpler alternative to:
+		 (gdb) p ((float (*) (float, float)) mult) (2.0f, 3.0f)
+	     */
+	    prototyped = 1;
+	  }
 	else if (i < TYPE_NFIELDS (ftype))
 	  prototyped = TYPE_PROTOTYPED (ftype);
 	else
diff --git a/gdb/infcall.h b/gdb/infcall.h
index cbaa943b241..a456d92e044 100644
--- a/gdb/infcall.h
+++ b/gdb/infcall.h
@@ -35,9 +35,15 @@ extern CORE_ADDR find_function_addr (struct value *function,
    representing what the function returned.  May fail to return, if a
    breakpoint or signal is hit during the execution of the function.
 
+   DFEAULT_RETURN_TYPE is used as function return type if the return
+   type is unknown.  This is used when calling functions with no debug
+   info.
+
    ARGS is modified to contain coerced values.  */
 
-extern struct value *call_function_by_hand (struct value *function, int nargs,
+extern struct value *call_function_by_hand (struct value *function,
+					    type *default_return_type,
+					    int nargs,
 					    struct value **args);
 
 /* Similar to call_function_by_hand and additional call
@@ -45,9 +51,18 @@ extern struct value *call_function_by_hand (struct value *function, int nargs,
    created inferior call dummy frame.  */
 
 extern struct value *
-  call_function_by_hand_dummy (struct value *function, int nargs,
+  call_function_by_hand_dummy (struct value *function,
+			       type *default_return_type,
+			       int nargs,
 			       struct value **args,
 			       dummy_frame_dtor_ftype *dummy_dtor,
 			       void *dummy_dtor_data);
 
+/* Throw an error indicating that the user tried to call a function
+   that has unknown return type.  FUNC_NAME is the name of the
+   function to be included in the error message; may be NULL, in which
+   case the error message doesn't include a function name.  */
+
+extern void error_call_unknown_return_type (const char *func_name);
+
 #endif
diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 573a3e9ecf0..16403c96016 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -248,7 +248,7 @@ call_lseek (int fd, off_t offset, int whence)
 {
   char exp[80];
 
-  snprintf (&exp[0], sizeof (exp), "lseek (%d, %ld, %d)",
+  snprintf (&exp[0], sizeof (exp), "(long) lseek (%d, %ld, %d)",
 	    fd, (long) offset, whence);
   return (off_t) parse_and_eval_long (&exp[0]);
 }
@@ -492,7 +492,7 @@ inferior_call_waitpid (ptid_t pptid, int pid)
   argv[2] = value_from_longest (builtin_type (gdbarch)->builtin_int, 0);
   argv[3] = 0;
 
-  retv = call_function_by_hand (waitpid_fn, 3, argv);
+  retv = call_function_by_hand (waitpid_fn, NULL, 3, argv);
   if (value_as_long (retv) < 0)
     goto out;
 
@@ -707,7 +707,7 @@ checkpoint_command (char *args, int from_tty)
     scoped_restore save_pid
       = make_scoped_restore (&checkpointing_pid, ptid_get_pid (inferior_ptid));
 
-    ret = call_function_by_hand (fork_fn, 0, &ret);
+    ret = call_function_by_hand (fork_fn, NULL, 0, &ret);
   }
 
   if (!ret)	/* Probably can't happen.  */
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index f5389a07f9f..eb446599528 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -2448,7 +2448,7 @@ linux_infcall_mmap (CORE_ADDR size, unsigned prot)
   arg[ARG_FD] = value_from_longest (builtin_type (gdbarch)->builtin_int, -1);
   arg[ARG_OFFSET] = value_from_longest (builtin_type (gdbarch)->builtin_int64,
 					0);
-  addr_val = call_function_by_hand (mmap_val, ARG_LAST, arg);
+  addr_val = call_function_by_hand (mmap_val, NULL, ARG_LAST, arg);
   retval = value_as_address (addr_val);
   if (retval == (CORE_ADDR) -1)
     error (_("Failed inferior mmap call for %s bytes, errno is changed."),
@@ -2477,7 +2477,7 @@ linux_infcall_munmap (CORE_ADDR addr, CORE_ADDR size)
   /* Assuming sizeof (unsigned long) == sizeof (size_t).  */
   arg[ARG_LENGTH] = value_from_ulongest
 		    (builtin_type (gdbarch)->builtin_unsigned_long, size);
-  retval_val = call_function_by_hand (munmap_val, ARG_LAST, arg);
+  retval_val = call_function_by_hand (munmap_val, NULL, ARG_LAST, arg);
   retval = value_as_long (retval_val);
   if (retval != 0)
     warning (_("Failed inferior munmap call at %s for %s bytes, "
diff --git a/gdb/m2-typeprint.c b/gdb/m2-typeprint.c
index 4cf15698fe3..0dd6f19fc7a 100644
--- a/gdb/m2-typeprint.c
+++ b/gdb/m2-typeprint.c
@@ -280,7 +280,8 @@ m2_procedure (struct type *type, struct ui_file *stream,
 {
   fprintf_filtered (stream, "PROCEDURE ");
   m2_type_name (type, stream);
-  if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
+  if (TYPE_TARGET_TYPE (type) == NULL
+      || TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
     {
       int i, len = TYPE_NFIELDS (type);
 
@@ -294,11 +295,11 @@ m2_procedure (struct type *type, struct ui_file *stream,
 	    }
 	  m2_print_type (TYPE_FIELD_TYPE (type, i), "", stream, -1, 0, flags);
 	}
+      fprintf_filtered (stream, ") : ");
       if (TYPE_TARGET_TYPE (type) != NULL)
-	{
-	  fprintf_filtered (stream, " : ");
-	  m2_print_type (TYPE_TARGET_TYPE (type), "", stream, 0, 0, flags);
-	}
+	m2_print_type (TYPE_TARGET_TYPE (type), "", stream, 0, 0, flags);
+      else
+	type_print_unknown_return_type (stream);
     }
 }
 
diff --git a/gdb/objc-lang.c b/gdb/objc-lang.c
index bd085142416..624310e3b01 100644
--- a/gdb/objc-lang.c
+++ b/gdb/objc-lang.c
@@ -130,7 +130,8 @@ lookup_objc_class (struct gdbarch *gdbarch, const char *classname)
 
   classval = value_string (classname, strlen (classname) + 1, char_type);
   classval = value_coerce_array (classval);
-  return (CORE_ADDR) value_as_long (call_function_by_hand (function, 
+  return (CORE_ADDR) value_as_long (call_function_by_hand (function,
+							   NULL,
 							   1, &classval));
 }
 
@@ -160,7 +161,7 @@ lookup_child_selector (struct gdbarch *gdbarch, const char *selname)
   selstring = value_coerce_array (value_string (selname, 
 						strlen (selname) + 1,
 						char_type));
-  return value_as_long (call_function_by_hand (function, 1, &selstring));
+  return value_as_long (call_function_by_hand (function, NULL, 1, &selstring));
 }
 
 struct value * 
@@ -181,12 +182,13 @@ value_nsstring (struct gdbarch *gdbarch, char *ptr, int len)
   if (lookup_minimal_symbol("_NSNewStringFromCString", 0, 0).minsym)
     {
       function = find_function_in_inferior("_NSNewStringFromCString", NULL);
-      nsstringValue = call_function_by_hand(function, 1, &stringValue[2]);
+      nsstringValue = call_function_by_hand(function,
+					    NULL, 1, &stringValue[2]);
     }
   else if (lookup_minimal_symbol("istr", 0, 0).minsym)
     {
       function = find_function_in_inferior("istr", NULL);
-      nsstringValue = call_function_by_hand(function, 1, &stringValue[2]);
+      nsstringValue = call_function_by_hand(function, NULL, 1, &stringValue[2]);
     }
   else if (lookup_minimal_symbol("+[NSString stringWithCString:]", 0, 0).minsym)
     {
@@ -198,7 +200,7 @@ value_nsstring (struct gdbarch *gdbarch, char *ptr, int len)
 	(type, lookup_objc_class (gdbarch, "NSString"));
       stringValue[1] = value_from_longest 
 	(type, lookup_child_selector (gdbarch, "stringWithCString:"));
-      nsstringValue = call_function_by_hand(function, 3, &stringValue[0]);
+      nsstringValue = call_function_by_hand(function, NULL, 3, &stringValue[0]);
     }
   else
     error (_("NSString: internal error -- no way to create new NSString"));
@@ -1209,7 +1211,7 @@ print_object_command (char *args, int from_tty)
   if (function == NULL)
     error (_("Unable to locate _NSPrintForDebugger in child process"));
 
-  description = call_function_by_hand (function, 1, &object);
+  description = call_function_by_hand (function, NULL, 1, &object);
 
   string_addr = value_as_long (description);
   if (string_addr == 0)
diff --git a/gdb/p-typeprint.c b/gdb/p-typeprint.c
index d08f6f792f6..33b4992c335 100644
--- a/gdb/p-typeprint.c
+++ b/gdb/p-typeprint.c
@@ -227,7 +227,8 @@ pascal_type_print_varspec_prefix (struct type *type, struct ui_file *stream,
     case TYPE_CODE_METHOD:
       if (passed_a_ptr)
 	fprintf_filtered (stream, "(");
-      if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
+      if (TYPE_TARGET_TYPE (type) != NULL
+	  && TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
 	{
 	  fprintf_filtered (stream, "function  ");
 	}
@@ -255,7 +256,8 @@ pascal_type_print_varspec_prefix (struct type *type, struct ui_file *stream,
       if (passed_a_ptr)
 	fprintf_filtered (stream, "(");
 
-      if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
+      if (TYPE_TARGET_TYPE (type) != NULL
+	  && TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
 	{
 	  fprintf_filtered (stream, "function  ");
 	}
@@ -334,6 +336,33 @@ pascal_print_func_args (struct type *type, struct ui_file *stream,
     }
 }
 
+/* Helper for pascal_type_print_varspec_suffix to print the suffix of
+   a function or method.  */
+
+static void
+pascal_type_print_func_varspec_suffix  (struct type *type, struct ui_file *stream,
+					int show, int passed_a_ptr,
+					int demangled_args,
+					const struct type_print_options *flags)
+{
+  if (TYPE_TARGET_TYPE (type) == NULL
+      || TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
+    {
+      fprintf_filtered (stream, " : ");
+      pascal_type_print_varspec_prefix (TYPE_TARGET_TYPE (type),
+					stream, 0, 0, flags);
+
+      if (TYPE_TARGET_TYPE (type) == NULL)
+	type_print_unknown_return_type (stream);
+      else
+	pascal_type_print_base (TYPE_TARGET_TYPE (type), stream, show, 0,
+				flags);
+
+      pascal_type_print_varspec_suffix (TYPE_TARGET_TYPE (type), stream, 0,
+					passed_a_ptr, 0, flags);
+    }
+}
+
 /* Print any array sizes, function arguments or close parentheses
    needed after the variable name (to describe its type).
    Args work like pascal_type_print_varspec_prefix.  */
@@ -365,16 +394,8 @@ pascal_type_print_varspec_suffix (struct type *type, struct ui_file *stream,
       pascal_type_print_method_args ("",
 				     "",
 				     stream);
-      if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
-	{
-	  fprintf_filtered (stream, " : ");
-	  pascal_type_print_varspec_prefix (TYPE_TARGET_TYPE (type),
-					    stream, 0, 0, flags);
-	  pascal_type_print_base (TYPE_TARGET_TYPE (type), stream, show, 0,
-				  flags);
-	  pascal_type_print_varspec_suffix (TYPE_TARGET_TYPE (type), stream, 0,
-					    passed_a_ptr, 0, flags);
-	}
+      pascal_type_print_func_varspec_suffix (type, stream, show,
+					     passed_a_ptr, 0, flags);
       break;
 
     case TYPE_CODE_PTR:
@@ -388,16 +409,8 @@ pascal_type_print_varspec_suffix (struct type *type, struct ui_file *stream,
 	fprintf_filtered (stream, ")");
       if (!demangled_args)
 	pascal_print_func_args (type, stream, flags);
-      if (TYPE_CODE (TYPE_TARGET_TYPE (type)) != TYPE_CODE_VOID)
-	{
-	  fprintf_filtered (stream, " : ");
-	  pascal_type_print_varspec_prefix (TYPE_TARGET_TYPE (type),
-					    stream, 0, 0, flags);
-	  pascal_type_print_base (TYPE_TARGET_TYPE (type), stream, show, 0,
-				  flags);
-	  pascal_type_print_varspec_suffix (TYPE_TARGET_TYPE (type), stream, 0,
-					    passed_a_ptr, 0, flags);
-	}
+      pascal_type_print_func_varspec_suffix (type, stream, show,
+					     passed_a_ptr, 0, flags);
       break;
 
     case TYPE_CODE_UNDEF:
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index b5a0ef86d24..cbbb9362ec9 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -925,7 +925,8 @@ valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
       scoped_value_mark free_values;
       struct value *return_value;
 
-      return_value = call_function_by_hand (function, args_count, vargs);
+      return_value = call_function_by_hand (function, NULL,
+					    args_count, vargs);
       result = value_to_value_object (return_value);
     }
   CATCH (except, RETURN_MASK_ALL)
diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
index 817976ab33a..c5764bf8d12 100644
--- a/gdb/rust-lang.c
+++ b/gdb/rust-lang.c
@@ -1290,7 +1290,7 @@ rust_evaluate_funcall (struct expression *exp, int *pos, enum noside noside)
   if (noside == EVAL_AVOID_SIDE_EFFECTS)
     result = value_zero (TYPE_TARGET_TYPE (fn_type), not_lval);
   else
-    result = call_function_by_hand (function, num_args + 1, args.data ());
+    result = call_function_by_hand (function, NULL, num_args + 1, args.data ());
   return result;
 }
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 35c5928def4..c00c30038c5 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,29 @@
 2017-09-04  Pedro Alves  <palves@redhat.com>
 
+	* gdb.base/break-main-file-remove-fail.exp (test_remove_bp): Cast
+	return type of munmap in infcall.
+	* gdb.base/break-probes.exp: Cast return type of foo in infcall.
+	* gdb.base/checkpoint.exp: Simplify using for loop.  Cast return
+	type of ftell in infcall.
+	* gdb.base/dprintf-detach.exp (dprintf_detach_test): Cast return
+	type of getpid in infcall.
+	* gdb.base/infcall-exec.exp: Cast return type of execlp in
+	infcall.
+	* gdb.base/info-os.exp: Cast return type of getpid in infcall.
+	Bail on failure to extract the pid.
+	* gdb.base/nodebug.c: #include <stdint.h>.
+	(multf, multf_noproto, mult, mult_noproto, add8, add8_noproto):
+	New functions.
+	* gdb.base/nodebug.exp (test_call_promotion): New procedure.
+	Change expected output of print/whatis/ptype with functions with
+	no debug info.  Test all supported languages.  Call
+	test_call_promotion.
+	* gdb.compile/compile.exp: Adjust expected output to expect
+	warning.
+	* gdb.threads/siginfo-threads.exp: Likewise.
+
+2017-09-04  Pedro Alves  <palves@redhat.com>
+
 	* gdb.base/callfuncs.exp (do_function_calls): New parameter
 	"prototypes".  Test calling float functions via prototyped and
 	unprototyped function pointers.
diff --git a/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp b/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
index eba72bc85d1..080d193a347 100644
--- a/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
+++ b/gdb/testsuite/gdb.base/break-main-file-remove-fail.exp
@@ -88,7 +88,7 @@ proc test_remove_bp { initial_load } {
 	# should warn the user about it.
 	set pagesize [get_integer_valueof "pg_size" 0]
 	set align_addr [expr $bp_addr - $bp_addr % $pagesize]
-	set munmap [get_integer_valueof "munmap ($align_addr, $pagesize)" -1]
+	set munmap [get_integer_valueof "(int) munmap ($align_addr, $pagesize)" -1]
 
 	if {$munmap != 0} {
 	    unsupported "can't munmap foo's page"
diff --git a/gdb/testsuite/gdb.base/break-probes.exp b/gdb/testsuite/gdb.base/break-probes.exp
index 929509a015d..318a21993e0 100644
--- a/gdb/testsuite/gdb.base/break-probes.exp
+++ b/gdb/testsuite/gdb.base/break-probes.exp
@@ -86,5 +86,5 @@ if { $using_probes } {
     }
 
     # Call something to ensure that relocation occurred
-    gdb_test "call foo(23)" "\\\$.* = 31.*\\\M.*"
+    gdb_test "call (int) foo(23)" "\\\$.* = 31.*\\\M.*"
 }
diff --git a/gdb/testsuite/gdb.base/checkpoint.exp b/gdb/testsuite/gdb.base/checkpoint.exp
index 12c1d8ae142..677c3892fd7 100644
--- a/gdb/testsuite/gdb.base/checkpoint.exp
+++ b/gdb/testsuite/gdb.base/checkpoint.exp
@@ -224,45 +224,11 @@ gdb_test "shell diff $pi_txt $copy1_txt" \
 delete_breakpoints
 gdb_breakpoint $break2_loc
 
-gdb_test "restart 1" "if .c == EOF.*" "restart 1 three"
-gdb_test "continue" "breakpoint 2.*" "break2 1 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 1"
-
-gdb_test "restart 2" "if .c == EOF.*" "restart 2 three"
-gdb_test "continue" "breakpoint 2.*" "break2 2 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 2"
-
-gdb_test "restart 3" "if .c == EOF.*" "restart 3 three"
-gdb_test "continue" "breakpoint 2.*" "break2 3 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 3"
-
-gdb_test "restart 4" "if .c == EOF.*" "restart 4 three"
-gdb_test "continue" "breakpoint 2.*" "break2 4 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 4"
-
-gdb_test "restart 5" "if .c == EOF.*" "restart 5 three"
-gdb_test "continue" "breakpoint 2.*" "break2 5 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 5"
-
-gdb_test "restart 6" "if .c == EOF.*" "restart 6 three"
-gdb_test "continue" "breakpoint 2.*" "break2 6 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 6"
-
-gdb_test "restart 7" "if .c == EOF.*" "restart 7 three"
-gdb_test "continue" "breakpoint 2.*" "break2 7 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 7"
-
-gdb_test "restart 8" "if .c == EOF.*" "restart 8 three"
-gdb_test "continue" "breakpoint 2.*" "break2 8 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 8"
-
-gdb_test "restart 9" "if .c == EOF.*" "restart 9 three"
-gdb_test "continue" "breakpoint 2.*" "break2 9 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 9"
-
-gdb_test "restart 10" "if .c == EOF.*" "restart 10 three"
-gdb_test "continue" "breakpoint 2.*" "break2 10 one"
-gdb_test "print ftell (out) > 100000" " = 1.*" "outfile still open 10"
+for {set num 1} {$num <= 10} {incr num} {
+    gdb_test "restart $num" "if .c == EOF.*" "restart $num three"
+    gdb_test "continue" "breakpoint 2.*" "break2 $num one"
+    gdb_test "print (long) ftell (out) > 100000" " = 1.*" "outfile still open $num"
+}
 
 #
 # Now confirm that if one fork exits, we automatically switch to another one.
diff --git a/gdb/testsuite/gdb.base/dprintf-detach.exp b/gdb/testsuite/gdb.base/dprintf-detach.exp
index 4c6ef1cf3c5..940a9ef537e 100644
--- a/gdb/testsuite/gdb.base/dprintf-detach.exp
+++ b/gdb/testsuite/gdb.base/dprintf-detach.exp
@@ -53,7 +53,7 @@ proc dprintf_detach_test { breakpoint_always_inserted dprintf_style disconnected
 	# Get PID of test program.
 	set inferior_pid -1
 	set test "get inferior process ID"
-	gdb_test_multiple "call getpid ()" $test {
+	gdb_test_multiple "call (int) getpid ()" $test {
 	    -re ".* = ($decimal).*$gdb_prompt $" {
 		set inferior_pid $expect_out(1,string)
 		pass $test
diff --git a/gdb/testsuite/gdb.base/infcall-exec.exp b/gdb/testsuite/gdb.base/infcall-exec.exp
index 39840769cf3..8419905e9cb 100644
--- a/gdb/testsuite/gdb.base/infcall-exec.exp
+++ b/gdb/testsuite/gdb.base/infcall-exec.exp
@@ -44,5 +44,5 @@ append expected_result "\[\r\n\]+.*"
 append expected_result "Breakpoint 1, main .*at .*$srcfile2:$decimal"
 append expected_result ".*"
 
-gdb_test "call execlp \(\"$binfile2\", \"$binfile2\", \(char \*\)0\)" \
+gdb_test "call (int) execlp \(\"$binfile2\", \"$binfile2\", \(char \*\)0\)" \
     $expected_result "call execlp"
diff --git a/gdb/testsuite/gdb.base/info-os.exp b/gdb/testsuite/gdb.base/info-os.exp
index 0168ccb3c18..574da26c331 100644
--- a/gdb/testsuite/gdb.base/info-os.exp
+++ b/gdb/testsuite/gdb.base/info-os.exp
@@ -39,14 +39,18 @@ if ![runto_main] then {
 }
 
 # Get PID of test program.
-set inferior_pid -1
+set inferior_pid ""
 set test "get inferior process ID"
-gdb_test_multiple "call getpid()" $test {
+gdb_test_multiple "call (int) getpid()" $test {
     -re ".* = ($decimal).*$gdb_prompt $" {
 	set inferior_pid $expect_out(1,string)
 	pass $test
     }
 }
+if {$inferior_pid == ""} {
+    untested "failed to get pid"
+    return
+}
 
 gdb_breakpoint ${srcfile}:[gdb_get_line_number "Set breakpoint here"]
 gdb_continue_to_breakpoint "Set breakpoint here"
diff --git a/gdb/testsuite/gdb.base/nodebug.c b/gdb/testsuite/gdb.base/nodebug.c
index eb5d661a095..99641e80121 100644
--- a/gdb/testsuite/gdb.base/nodebug.c
+++ b/gdb/testsuite/gdb.base/nodebug.c
@@ -1,4 +1,6 @@
 #include <stdlib.h>
+#include <stdint.h>
+
 /* Test that things still (sort of) work when compiled without -g.  */
 
 int dataglobal = 3;			/* Should go in global data */
@@ -43,3 +45,42 @@ int array_index (char *arr, int i)
   free (x);
   return retval;
 }
+
+float
+multf (float v1, float v2)
+{
+  return v1 * v2;
+}
+
+float
+multf_noproto (v1, v2)
+  float v1, v2;
+{
+  return v1 * v2;
+}
+
+double
+mult (double v1, double v2)
+{
+  return v1 * v2;
+}
+
+double
+mult_noproto (v1, v2)
+  double v1, v2;
+{
+  return v1 * v2;
+}
+
+uint8_t
+add8 (uint8_t v1, uint8_t v2)
+{
+  return v1 + v2;
+}
+
+uint8_t
+add8_noproto (v1, v2)
+  uint8_t v1, v2;
+{
+  return v1 + v2;
+}
diff --git a/gdb/testsuite/gdb.base/nodebug.exp b/gdb/testsuite/gdb.base/nodebug.exp
index a54e5bb65ed..7bdf9ad7662 100644
--- a/gdb/testsuite/gdb.base/nodebug.exp
+++ b/gdb/testsuite/gdb.base/nodebug.exp
@@ -39,6 +39,40 @@ if  { [gdb_compile $srcdir/$subdir/$srcfile $binfile executable $exec_opts] != "
 
 clean_restart $binfile
 
+# Test calling no-debug functions involving argument types that may
+# require coercion/promotion, both prototyped and unprototyped, both
+# return-type-cast style, and function-pointer-cast styles.
+proc test_call_promotion {} {
+    if [target_info exists gdb,cannot_call_functions] {
+	return
+    }
+
+    # Call prototyped function with float parameters via both
+    # return-type cast and function-pointer cast.  This checks that
+    # GDB doesn't do float->double coercion.
+    gdb_test "p (float) multf(2.0f, 3.0f)" " = 6"
+    gdb_test "p ((float (*) (float, float)) multf)(2, 3)" " = 6"
+    gdb_test "p ((float (*) (float, float)) multf)(2.0f, 3.0f)" " = 6"
+
+    # Call unprototyped function with float parameters via
+    # function-pointer cast, only.  return-type cast assumes
+    # protototyped.  Check that GDB does float->double coercion.
+    gdb_test "p ((float (*) ()) multf_noproto)(2.0f, 3.0f)" " = 6"
+    gdb_test "p ((float (*) ()) multf_noproto)(2.0, 3.0)" " = 6"
+
+    # Same, but for double.
+    gdb_test "p (double) mult (2.0, 3.0)" " = 6"
+    gdb_test "p ((double (*) (double, double)) mult)(2.0f, 3.0f)" " = 6"
+    gdb_test "p ((double (*) (double, double)) mult)(2, 3)" " = 6"
+    gdb_test "p ((double (*) ()) mult_noproto)(2.0f, 3.0f)" " = 6"
+    gdb_test "p ((double (*) ()) mult_noproto)(2.0, 3.0)" " = 6"
+
+    # Check that GDB promotes char->int correctly.
+    gdb_test "p /d (uint8) add8((uint8) 2, (uint8) 3)" " = 5"
+    gdb_test "p /d ((uint8 (*) (uint8, uint8)) add8)((uint8) 2, (uint8) 3)" " = 5"
+    gdb_test "p /d ((uint8 (*) ()) add8_noproto)((uint8) 2, (uint8) 3)" " = 5"
+}
+
 if [runto inner] then {
     
     # Expect to find global/local symbols in each of text/data/bss.
@@ -59,18 +93,66 @@ if [runto inner] then {
     # out debugging info for non-aggregate return values of functions
     # even without -g, which should be accepted.
 
-    gdb_test "p top" \
-	"\{(<(text variable|function), no debug info>|short \\(int\\)|short \\(\\))\} \[0-9a-fx]* <\\.?top(\\(int\\)|)>"
-    gdb_test "whatis top" \
-	"(<(text variable|function), no debug info>|short \\(int\\)|short \\(\\))"
-    gdb_test "ptype top" "(short|int) \\((|void|int|<non-float parameter>|<non-float parameter>, <non-float parameter>)\\)"
-    
-    gdb_test "p middle" \
-	"\{(<(text variable|function), no debug info>|short \\(int\\)|short \\(\\))\} \[0-9a-fx]* <\\.?middle(\\(int\\)|)>"
-    gdb_test "whatis middle" \
-	"(<(text variable|function), no debug info>|short \\(int\\)|short \\(\\))"
-    gdb_test "ptype middle" "(short|int) \\((|void|int|<non-float parameter>|<non-float parameter>, <non-float parameter>)\\)"
-    
+    with_test_prefix "func" {
+	# Most languages default to printing like C.
+	set c_print_re " = \\{<text variable, no debug info>\\} $hex <top>"
+	set c_whatis_re " = <text variable, no debug info>"
+	set c_ptype_re "= <unknown return type> \\(\\)"
+
+	set cxx_ptype_re "= <unknown return type> \\(void\\)"
+
+	set ada_ptype_re " = function return <unknown return type>"
+
+	set m2_print_re " = \\{PROCEDURE <text variable, no debug info> \\(\\) : <unknown return type>\\} $hex <top>"
+	set m2_whatis_re "PROCEDURE <text variable, no debug info> \\(\\) : <unknown return type>"
+	set m2_ptype_re $m2_whatis_re
+
+	# Rust can't access minsyms?
+	set rust_nosym "No symbol 'top' in current context"
+
+	set pascal_ptype_re "type = procedure  : <unknown return type>"
+
+	#LANG		#PRINT		#WHATIS		#PTYPE
+	foreach lang_line {
+	    {"ada"		$c_print_re	$c_whatis_re	$ada_ptype_re}
+	    {"asm"		$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"c"		$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"c++"		$c_print_re	$c_whatis_re	$cxx_ptype_re}
+	    {"d"		$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"fortran"	$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"go"		$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"minimal"	$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"modula-2"	$m2_print_re	$m2_whatis_re	$m2_ptype_re}
+	    {"objective-c"	$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"opencl"	$c_print_re	$c_whatis_re	$c_ptype_re}
+	    {"pascal"	$c_print_re	$c_whatis_re	$pascal_ptype_re}
+	    {"rust"		$rust_nosym	$rust_nosym	$rust_nosym}
+	} {
+	    set lang [lindex $lang_line 0]
+	    set print_re [lindex $lang_line 1]
+	    set whatis_re [lindex $lang_line 2]
+	    set ptype_re [lindex $lang_line 3]
+
+	    set print_re [subst "$print_re"]
+	    set whatis_re [subst "$whatis_re"]
+	    set ptype_re [subst "$ptype_re"]
+
+	    with_test_prefix "$lang" {
+		gdb_test_no_output "set language $lang"
+		gdb_test "p top" $print_re
+		gdb_test "whatis top" $whatis_re
+		gdb_test "ptype top" $ptype_re
+	    }
+	}
+    }
+
+    gdb_test_no_output "set language auto"
+
+    # We can't rely on uintXX_t being available/known to GDB because
+    # we may or may not have debug info for those (depending on
+    # whether we have debug info for the C runtime, for example).
+    gdb_test_no_output "macro define uint8 unsigned char"
+
     gdb_test "p dataglobal" "= 3"
     gdb_test "whatis dataglobal" \
 	"<(data variable|variable), no debug info>|int"
@@ -122,17 +204,27 @@ if [runto inner] then {
     
     # This test is not as obscure as it might look.  `p getenv ("TERM")'
     # is a real-world example, at least on many systems.
+
+    gdb_test {p/c array_index("abcdef",2)} \
+	"'array_index' has unknown return type; cast the call to its declared return type"
+    gdb_test {ptype array_index("abcdef",2)} \
+	"function has unknown return type; cast the call to its declared return type"
+    gdb_test {whatis array_index("abcdef",2)} \
+	"function has unknown return type; cast the call to its declared return type"
+
     if [target_info exists gdb,cannot_call_functions] {
-	unsupported "p/c array_index(\"abcdef\",2)"
+	unsupported "p/c (int) array_index(\"abcdef\",2)"
     } else {
 	# We need to up this because this can be really slow on some boards.
 	# (malloc() is called as part of the test).
 	set prev_timeout $timeout
 	set timeout 60
-	gdb_test {p/c array_index("abcdef",2)} " = 99 'c'"
+	gdb_test {p/c (int) array_index("abcdef",2)} " = 99 'c'"
 	set timeout $prev_timeout
     }
-    
+
+    test_call_promotion
+
     # Now, try that we can give names of file-local symbols which happen
     # to be unique, and have it still work
     if [runto middle] then {
diff --git a/gdb/testsuite/gdb.compile/compile.exp b/gdb/testsuite/gdb.compile/compile.exp
index b2218704cb4..c23ff6aabd5 100644
--- a/gdb/testsuite/gdb.compile/compile.exp
+++ b/gdb/testsuite/gdb.compile/compile.exp
@@ -296,12 +296,14 @@ gdb_test "p globalvar" " = 77" "expect 77"
 
 # Test reference to minimal_symbol, not (full) symbol.
 
-gdb_test_no_output "compile code globalvar = func_nodebug (75);" \
+gdb_test "compile code globalvar = func_nodebug (75);" \
+    "warning: function has unknown return type; assuming int" \
     "call func_nodebug"
 gdb_test "p globalvar" " = -75" "expect -75"
-gdb_test_no_output \
-  "compile code int (*funcp) (int) = func_nodebug; globalvar = funcp (76);" \
-  "call func_nodebug indirectly"
+gdb_test \
+    "compile code int (*funcp) (int) = func_nodebug; globalvar = funcp (76);" \
+    "warning: function has unknown return type; assuming int" \
+    "call func_nodebug indirectly"
 gdb_test "p globalvar" " = -76" "expect -76"
 
 
diff --git a/gdb/testsuite/gdb.threads/siginfo-threads.exp b/gdb/testsuite/gdb.threads/siginfo-threads.exp
index 328168c8eb3..8ee4c36644c 100644
--- a/gdb/testsuite/gdb.threads/siginfo-threads.exp
+++ b/gdb/testsuite/gdb.threads/siginfo-threads.exp
@@ -40,12 +40,17 @@ gdb_test "handle SIGUSR2 stop print pass" \
 gdb_breakpoint [gdb_get_line_number "break-at-exit"]
 
 set test "get pid"
-gdb_test_multiple "p getpid ()" $test {
+set pid ""
+gdb_test_multiple "p (int) getpid ()" $test {
     -re " = (\[0-9\]+)\r\n$gdb_prompt $" {
 	set pid $expect_out(1,string)
 	pass $test
     }
 }
+if {$pid == ""} {
+    untested "failed to get pid"
+    return
+}
 
 for {set sigcount 0} {$sigcount < 4} {incr sigcount} {
     set test "catch signal $sigcount"
diff --git a/gdb/typeprint.c b/gdb/typeprint.c
index 045271a8074..8e58bf9b5f8 100644
--- a/gdb/typeprint.c
+++ b/gdb/typeprint.c
@@ -386,6 +386,14 @@ type_to_string (struct type *type)
   return {};
 }
 
+/* See typeprint.h.  */
+
+void
+type_print_unknown_return_type (struct ui_file *stream)
+{
+  fprintf_filtered (stream, _("<unknown return type>"));
+}
+
 /* Print type of EXP, or last thing in value history if EXP == NULL.
    show is passed to type_print.  */
 
@@ -757,4 +765,3 @@ val_print_not_associated (struct ui_file *stream)
 {
   fprintf_filtered (stream, _("<not associated>"));
 }
-
diff --git a/gdb/typeprint.h b/gdb/typeprint.h
index 72da7f485b9..d4e19e5b881 100644
--- a/gdb/typeprint.h
+++ b/gdb/typeprint.h
@@ -74,6 +74,10 @@ void c_type_print_varspec_suffix (struct type *, struct ui_file *, int,
 void c_type_print_args (struct type *, struct ui_file *, int, enum language,
 			const struct type_print_options *);
 
+/* Print <unknown return type> to stream STREAM.  */
+
+void type_print_unknown_return_type (struct ui_file *stream);
+
 extern void val_print_not_allocated (struct ui_file *stream);
 
 extern void val_print_not_associated (struct ui_file *stream);
diff --git a/gdb/valarith.c b/gdb/valarith.c
index 9724acace78..bcc5ff6c0a9 100644
--- a/gdb/valarith.c
+++ b/gdb/valarith.c
@@ -505,7 +505,7 @@ value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
 	    = TYPE_TARGET_TYPE (check_typedef (value_type (argvec[0])));
 	  return value_zero (return_type, VALUE_LVAL (arg1));
 	}
-      return call_function_by_hand (argvec[0], 2 - static_memfuncp,
+      return call_function_by_hand (argvec[0], NULL, 2 - static_memfuncp,
 				    argvec + 1);
     }
   throw_error (NOT_FOUND_ERROR,
@@ -624,7 +624,7 @@ value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
 	    = TYPE_TARGET_TYPE (check_typedef (value_type (argvec[0])));
 	  return value_zero (return_type, VALUE_LVAL (arg1));
 	}
-      return call_function_by_hand (argvec[0], nargs, argvec + 1);
+      return call_function_by_hand (argvec[0], NULL, nargs, argvec + 1);
     }
   throw_error (NOT_FOUND_ERROR,
                _("member function %s not found"), tstr);
diff --git a/gdb/valops.c b/gdb/valops.c
index c1bb93776ad..f5e3aabbf8f 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -192,7 +192,7 @@ value_allocate_space_in_inferior (int len)
   struct value *blocklen;
 
   blocklen = value_from_longest (builtin_type (gdbarch)->builtin_int, len);
-  val = call_function_by_hand (val, 1, &blocklen);
+  val = call_function_by_hand (val, NULL, 1, &blocklen);
   if (value_logical_not (val))
     {
       if (!target_has_execution)