Fix "control reaches end of non-void function" errors in testsuite

When running the testsuite with clang, a number of testcases fail to
build with the following errors:
  warning: control reaches end of non-void function [-Wreturn-type]
  warning: control may reach end of non-void function [-Wreturn-type]

This prevents a number of testcases from executing.  This commit fixes.

gdb/testsuite/ChangeLog:

	* gdb.base/info-os.c (main): Add return statement.
	* gdb.base/info_minsym.c (minsym_fun): Likewise.
	* gdb.base/large-frame-2.c (func): Likewise.
	* gdb.base/pr10179-a.c (foo1, bar1): Likewise.
	* gdb.base/pr10179-b.c (foo2): Likewise.
	* gdb.base/valgrind-disp-step.c (foo): Likewise.
	* gdb.base/watch-cond.c (func): Likewise.
	* gdb.multi/goodbye.c (verylongfun): Likewise.
	* gdb.multi/hello.c (commonfun): Likewise.
	* gdb.python/py-finish-breakpoint.c (call_longjmp): Likewise.
	* gdb.threads/fork-plus-threads.c (thread_func): Likewise.
	* gdb.threads/forking-threads-plus-breakpoint.c (thread_forks):
	Likewise.
	* gdb.threads/hand-call-new-thread.c (foo): Likewise.
	* gdb.threads/interrupt-while-step-over.c (child_function):
	Likewise.
	* gdb.trace/actions-changed.c (end): Likewise.

16 files changed, 39 insertions, 1 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 3702032fb68..dda5b684732 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,25 @@
 2020-05-15  Gary Benson <gbenson@redhat.com>
 
+	* gdb.base/info-os.c (main): Add return statement.
+	* gdb.base/info_minsym.c (minsym_fun): Likewise.
+	* gdb.base/large-frame-2.c (func): Likewise.
+	* gdb.base/pr10179-a.c (foo1, bar1): Likewise.
+	* gdb.base/pr10179-b.c (foo2): Likewise.
+	* gdb.base/valgrind-disp-step.c (foo): Likewise.
+	* gdb.base/watch-cond.c (func): Likewise.
+	* gdb.multi/goodbye.c (verylongfun): Likewise.
+	* gdb.multi/hello.c (commonfun): Likewise.
+	* gdb.python/py-finish-breakpoint.c (call_longjmp): Likewise.
+	* gdb.threads/fork-plus-threads.c (thread_func): Likewise.
+	* gdb.threads/forking-threads-plus-breakpoint.c (thread_forks):
+	Likewise.
+	* gdb.threads/hand-call-new-thread.c (foo): Likewise.
+	* gdb.threads/interrupt-while-step-over.c (child_function):
+	Likewise.
+	* gdb.trace/actions-changed.c (end): Likewise.
+
+2020-05-15  Gary Benson <gbenson@redhat.com>
+
 	* gdb.opencl/callfuncs.exp: Report when test skipped.
 	* gdb.opencl/convs_casts.exp: Likewise.
 	* gdb.opencl/datatypes.exp: Likewise.
diff --git a/gdb/testsuite/gdb.base/info-os.c b/gdb/testsuite/gdb.base/info-os.c
index f08407f02f2..5b88c2661ee 100644
--- a/gdb/testsuite/gdb.base/info-os.c
+++ b/gdb/testsuite/gdb.base/info-os.c
@@ -48,6 +48,8 @@ thread_proc (void *args)
 {
   pthread_mutex_lock (&mutex);
   pthread_mutex_unlock (&mutex);
+
+  return NULL;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/info_minsym.c b/gdb/testsuite/gdb.base/info_minsym.c
index b4e3a3f3391..6f774b6fe68 100644
--- a/gdb/testsuite/gdb.base/info_minsym.c
+++ b/gdb/testsuite/gdb.base/info_minsym.c
@@ -20,6 +20,7 @@ static int minsym_var;
 static int minsym_fun (void)
 {
    minsym_var++;
+   return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/large-frame-2.c b/gdb/testsuite/gdb.base/large-frame-2.c
index bc2cc8482aa..7a88f57c5cd 100644
--- a/gdb/testsuite/gdb.base/large-frame-2.c
+++ b/gdb/testsuite/gdb.base/large-frame-2.c
@@ -22,4 +22,5 @@ func (void)
 {
   int a[4096];
   blah (a);
+  return 0;
 }
diff --git a/gdb/testsuite/gdb.base/pr10179-a.c b/gdb/testsuite/gdb.base/pr10179-a.c
index 56bce9df92e..584b1bc32a4 100644
--- a/gdb/testsuite/gdb.base/pr10179-a.c
+++ b/gdb/testsuite/gdb.base/pr10179-a.c
@@ -5,11 +5,13 @@ extern int foo2();
 int
 foo1()
 {
+  return 0;
 }
 
 int
 bar1()
 {
+  return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/pr10179-b.c b/gdb/testsuite/gdb.base/pr10179-b.c
index dcc5d9bb8b3..2f328ba5f39 100644
--- a/gdb/testsuite/gdb.base/pr10179-b.c
+++ b/gdb/testsuite/gdb.base/pr10179-b.c
@@ -3,4 +3,5 @@
 int
 foo2()
 {
+  return 0;
 }
diff --git a/gdb/testsuite/gdb.base/valgrind-disp-step.c b/gdb/testsuite/gdb.base/valgrind-disp-step.c
index 3a397ac1619..10de4aa2dc7 100644
--- a/gdb/testsuite/gdb.base/valgrind-disp-step.c
+++ b/gdb/testsuite/gdb.base/valgrind-disp-step.c
@@ -18,6 +18,7 @@
 static int
 foo (void)
 {
+  return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/watch-cond.c b/gdb/testsuite/gdb.base/watch-cond.c
index fe6fe9028f8..435f0b89c3d 100644
--- a/gdb/testsuite/gdb.base/watch-cond.c
+++ b/gdb/testsuite/gdb.base/watch-cond.c
@@ -23,6 +23,7 @@ int func(int *foo)
   (*foo)++;
   global++;
   global2++;
+  return 0;
 }
 
 void func2(int *foo)
diff --git a/gdb/testsuite/gdb.multi/goodbye.c b/gdb/testsuite/gdb.multi/goodbye.c
index 35a8d140e9c..7348d13f6a0 100644
--- a/gdb/testsuite/gdb.multi/goodbye.c
+++ b/gdb/testsuite/gdb.multi/goodbye.c
@@ -37,6 +37,7 @@ int verylongfun()
   glob *= 8;
   glob += 9;
   glob *= 9;
+  return 0;
 }
 
 void
diff --git a/gdb/testsuite/gdb.multi/hello.c b/gdb/testsuite/gdb.multi/hello.c
index ab535cd1829..d403addd72e 100644
--- a/gdb/testsuite/gdb.multi/hello.c
+++ b/gdb/testsuite/gdb.multi/hello.c
@@ -29,7 +29,7 @@ bar()
     exit(1);
 }
 
-int commonfun() { bar(); } /* from hello */
+int commonfun() { bar(); return 0; } /* from hello */
 
 int
 hello(int x)
diff --git a/gdb/testsuite/gdb.python/py-finish-breakpoint.c b/gdb/testsuite/gdb.python/py-finish-breakpoint.c
index 8b4c58c5407..83d439c08bb 100644
--- a/gdb/testsuite/gdb.python/py-finish-breakpoint.c
+++ b/gdb/testsuite/gdb.python/py-finish-breakpoint.c
@@ -56,6 +56,7 @@ int
 call_longjmp (jmp_buf *buf)
 {
   call_longjmp_1 (buf);
+  return 0;
 }
 
 void
diff --git a/gdb/testsuite/gdb.threads/fork-plus-threads.c b/gdb/testsuite/gdb.threads/fork-plus-threads.c
index 5600a9a8339..c29c4d9a95f 100644
--- a/gdb/testsuite/gdb.threads/fork-plus-threads.c
+++ b/gdb/testsuite/gdb.threads/fork-plus-threads.c
@@ -33,6 +33,7 @@ static void *
 thread_func (void *arg)
 {
   /* Empty.  */
+  return NULL;
 }
 
 static void
diff --git a/gdb/testsuite/gdb.threads/forking-threads-plus-breakpoint.c b/gdb/testsuite/gdb.threads/forking-threads-plus-breakpoint.c
index 38b25c42e64..7dcaee37968 100644
--- a/gdb/testsuite/gdb.threads/forking-threads-plus-breakpoint.c
+++ b/gdb/testsuite/gdb.threads/forking-threads-plus-breakpoint.c
@@ -90,6 +90,8 @@ thread_forks (void *arg)
 	  exit (1);
 	}
     }
+
+  return NULL;
 }
 
 /* Set this to tell the thread_breakpoint thread to exit.  */
diff --git a/gdb/testsuite/gdb.threads/hand-call-new-thread.c b/gdb/testsuite/gdb.threads/hand-call-new-thread.c
index f4a315d3d58..74042e40baf 100644
--- a/gdb/testsuite/gdb.threads/hand-call-new-thread.c
+++ b/gdb/testsuite/gdb.threads/hand-call-new-thread.c
@@ -24,6 +24,7 @@ static int
 foo (void)
 {
   usleep (1);
+  return 0;
 }
 
 static void *
diff --git a/gdb/testsuite/gdb.threads/interrupt-while-step-over.c b/gdb/testsuite/gdb.threads/interrupt-while-step-over.c
index e9e08b2a605..f76988743ae 100644
--- a/gdb/testsuite/gdb.threads/interrupt-while-step-over.c
+++ b/gdb/testsuite/gdb.threads/interrupt-while-step-over.c
@@ -44,6 +44,8 @@ child_function (void *arg)
   pthread_barrier_wait (&threads_started_barrier);
 
   infinite_loop ();
+
+  return NULL;
 }
 
 void
diff --git a/gdb/testsuite/gdb.trace/actions-changed.c b/gdb/testsuite/gdb.trace/actions-changed.c
index d3fead345a9..5b204d3c023 100644
--- a/gdb/testsuite/gdb.trace/actions-changed.c
+++ b/gdb/testsuite/gdb.trace/actions-changed.c
@@ -18,6 +18,7 @@
 int
 end (int i)
 {
+  return 0;
 }
 
 int