Teach gdb::option about string options

A following patch will make the "pipe" command use the gdb::option
framework for option processing.  However, "pipe"'s only option today
is a string option, "-d DELIM", and gdb::option does not support
string options yet.

This commit adds support for string options, mapped to var_string.
For now, a string is parsed up until the first whitespace.  I imagine
that we'll need to add support for quoting so that we could do:

 (gdb) cmd -option 'some -string'

without gdb confusing the "-string" for an option.

This doesn't seem important for pipe, so I'm leaving it for another
day.

One thing I'm not happy with, is that the string data is managed as a
raw malloc-allocated char *, which means that we need to xfree it
manually.  This is because var_string settings work that way too.
Although with var_string settings we're leaking the strings at gdb
exit, that was never really a problem.  For options though, leaking is
undesirable.

I think we should tackle that for both settings and options at the
same time, so for now I'm just managing the malloced data manually.
It's a bit ugly in option_def_and_value, but at least that's hidden
from view.

For testing, this adds a new "-string" option to "maint
test-settings", and then tweaks gdb.base/options.exp to exercise it.

gdb/ChangeLog:
2019-07-03  Pedro Alves  <palves@redhat.com>

	* cli/cli-option.c (union option_value) <string>: New field.
	(struct option_def_and_value): Add ctor, move ctor, dtor and
	use DISABLE_COPY_AND_ASSIGN.
	(option_def_and_value::clear_value): New.
	(parse_option, save_option_value_in_ctx, get_val_type_str)
	(add_setshow_cmds_for_options): Handle var_string.
	* cli-option.h (union option_def::var_address) <string>: New
	field.
	(struct string_option_def): New.
	* maint-test-options.c (struct test_options_opts): Add default
	ctor and use DISABLE_COPY_AND_ASSIGN.
	<string_opt>: New field.
	(test_options_opts::~test_options_opts): New.
	(test_options_opts::dump): Also dump "-string".
	(test_options_option_defs): Install "string.

gdb/testsuite/ChangeLog:
2019-07-03  Pedro Alves  <palves@redhat.com>

	* gdb.base/options.exp (expect_none, expect_flag, expect_bool)
	(expect_integer): Adjust to expect "-string".
	(expect_string): New.
	(all_options): Expect "-string".
	(test-flag, test-boolean): Adjust to expect "-string".
	(test-string): New proc.
	(top level): Call it.

1 files changed, 65 insertions, 17 deletions

diff --git a/gdb/testsuite/gdb.base/options.exp b/gdb/testsuite/gdb.base/options.exp
index 1a652b3c9dc..e8f571d9ba9 100644
--- a/gdb/testsuite/gdb.base/options.exp
+++ b/gdb/testsuite/gdb.base/options.exp
@@ -95,19 +95,19 @@ proc make_cmd {variant} {
 # test-options xxx", with no flag/option set.  OPERAND is the expected
 # operand.
 proc expect_none {operand} {
-    return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -- $operand"
+    return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -string '' -- $operand"
 }
 
 # Return a string for the expected result of running "maint
 # test-options xxx", with -flag set.  OPERAND is the expected operand.
 proc expect_flag {operand} {
-    return "-flag 1 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -- $operand"
+    return "-flag 1 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -string '' -- $operand"
 }
 
 # Return a string for the expected result of running "maint
 # test-options xxx", with -bool set.  OPERAND is the expected operand.
 proc expect_bool {operand} {
-    return "-flag 0 -xx1 0 -xx2 0 -bool 1 -enum xxx -uint 0 -zuint-unl 0 -- $operand"
+    return "-flag 0 -xx1 0 -xx2 0 -bool 1 -enum xxx -uint 0 -zuint-unl 0 -string '' -- $operand"
 }
 
 # Return a string for the expected result of running "maint
@@ -116,18 +116,26 @@ proc expect_bool {operand} {
 # expected operand.
 proc expect_integer {option val operand} {
     if {$option == "uinteger"} {
-	return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint $val -zuint-unl 0 -- $operand"
+	return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint $val -zuint-unl 0 -string '' -- $operand"
     } elseif {$option == "zuinteger-unlimited"} {
-	return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl $val -- $operand"
+	return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl $val -string '' -- $operand"
     } else {
 	error "unsupported option: $option"
     }
 }
 
+# Return a string for the expected result of running "maint
+# test-options xxx", with -string set to $STR.  OPERAND is the
+# expected operand.
+proc expect_string {str operand} {
+    return "-flag 0 -xx1 0 -xx2 0 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -string '$str' -- $operand"
+}
+
 set all_options {
     "-bool"
     "-enum"
     "-flag"
+    "-string"
     "-uinteger"
     "-xx1"
     "-xx2"
@@ -577,7 +585,7 @@ proc_with_prefix test-flag {variant} {
 
     # Extract twice the same flag, separated by one space.
     gdb_test "$cmd -xx1     -xx2 -xx1  -xx2 -xx1    -- non flags args" \
-	"-flag 0 -xx1 1 -xx2 1 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -- non flags args"
+	"-flag 0 -xx1 1 -xx2 1 -bool 0 -enum xxx -uint 0 -zuint-unl 0 -string '' -- non flags args"
 
     # Extract 2 known flags in front of unknown flags.
     gdb_test "$cmd -xx1 -xx2 -a -b -c -xx1 --" \
@@ -624,19 +632,11 @@ proc_with_prefix test-boolean {variant} {
     #   E.g., "frame apply all -past-main COMMAND".
 
     if {$variant == "require-delimiter"} {
+	set match_list $all_options
+	lappend match_list "off" "on"
 	res_test_gdb_complete_multiple \
 	    "1 [expect_none ""]" \
-	    "$cmd -bool " "" "" {
-	    "-bool"
-	    "-enum"
-	    "-flag"
-	    "-uinteger"
-	    "-xx1"
-	    "-xx2"
-	    "-zuinteger-unlimited"
-	    "off"
-	    "on"
-	}
+	    "$cmd -bool " "" "" $match_list
     } else {
 	res_test_gdb_complete_none "0 " "$cmd -bool "
     }
@@ -942,6 +942,53 @@ proc_with_prefix test-enum {variant} {
     gdb_test "$cmd -enum www --" "Undefined item: \"www\"."
 }
 
+# String option tests.
+proc_with_prefix test-string {variant} {
+    global all_options
+
+    set cmd [make_cmd $variant]
+
+    res_test_gdb_complete_none \
+	"1 [expect_none ""]" \
+	"$cmd -string "
+
+    # Check that "-" where a value is expected does not show the
+    # command's options.  I.e., a string's value is not optional.
+    # Check both completion and running the command.
+    res_test_gdb_complete_none \
+	"1 [expect_none ""]" \
+	"$cmd -string -"
+    gdb_test "$cmd -string --"\
+	"-string requires an argument"
+    if {$variant == "require-delimiter"} {
+	gdb_test "$cmd -string" [expect_none "-string"]
+    } else {
+	gdb_test "$cmd -string"\
+	    "-string requires an argument"
+    }
+
+    res_test_gdb_complete_none \
+	"1 [expect_none ""]" \
+	"$cmd -string STR"
+    gdb_test "$cmd -string STR --" [expect_string "STR" ""]
+
+    # Completing at "-" after parsing STR should list all options.
+    res_test_gdb_complete_multiple \
+	"1 [expect_string "STR" "-"]" \
+	"$cmd -string STR " "-" "" $all_options
+
+    # Check that only FOO is considered part of the string's value.
+    # I.e., that we stop parsing the string at the first whitespace.
+    if {$variant == "require-delimiter"} {
+	res_test_gdb_complete_none \
+	    "1 [expect_string "FOO" "BAR"]" \
+	    "$cmd -string FOO BAR"
+    } else {
+	res_test_gdb_complete_none "0 BAR" "$cmd -string FOO BAR"
+    }
+    gdb_test "$cmd -string FOO BAR --" "Unrecognized option at: BAR --"
+}
+
 # Run the options framework tests first.
 foreach_with_prefix cmd {
     "require-delimiter"
@@ -955,6 +1002,7 @@ foreach_with_prefix cmd {
 	test-uinteger $cmd $subcmd
     }
     test-enum $cmd
+    test-string $cmd
 }
 
 # Run the print integration tests, both as "standalone", and under