Documentation hyperlinks for [-Wname-of-option] (PR 87488)

This patch uses the support for pretty-printing escaped URLs added in
the previous patch (PR 87488) so that in a sufficiently capable terminal
the [-Wname-of-option] emitted at the end of each diagnostic becomes a
hyperlink to the documentation for that option on the GCC website.

I've tested it with Fedora 30's GNOME Terminal (3.32.2 with VTE 0.56.3);
the option text is printed with a dotted underline, hovering shows the
URL, and on right-clicking it offers menu items to visit/copy the URL.

gcc/ChangeLog:
	PR 87488
	* Makefile.in (CFLAGS-opts.o): Pass in DOCUMENTATION_ROOT_URL via
	-D.
	* configure.ac (--with-documentation-root-url): New option.
	* configure: Regenerate.
	* diagnostic-format-json.cc (json_end_diagnostic): If there is an
	option URL, add it as a new string field of the diagnostic option.
	* diagnostic.c (diagnostic_initialize): Initialize get_option_url.
	(print_option_information): If get_option_url is non-NULL, call
	it, and if the result is non-NULL, potentially emit an escape
	sequence to markup the option text with the resulting URL.
	* diagnostic.h (diagnostic_context::get_option_url): New callback.
	* doc/invoke.texi (-fdiagnostics-format=): Add "option_url" to
	example of JSON output.
	* opts-diagnostic.h (get_option_url): New decl.
	* opts.c (get_option_url): New function.
	* toplev.c (general_init): Initialize the get_option_url callback.

gcc/testsuite/ChangeLog:
	PR 87488
	* c-c++-common/diagnostic-format-json-2.c: Expect an "option_url"
	field.
	* c-c++-common/diagnostic-format-json-3.c: Likewise.
	* gfortran.dg/diagnostic-format-json-2.F90: Likewise.
	* gfortran.dg/diagnostic-format-json-3.F90: Likewise.
	* jit.dg/test-error-array-bounds.c (create_code): Ensure that
	error messages don't contain escaped URLs.

From-SVN: r276843

3 files changed, 10 insertions, 2 deletions

diff --git a/gcc/testsuite/c-c++-common/diagnostic-format-json-2.c b/gcc/testsuite/c-c++-common/diagnostic-format-json-2.c
index 239c75e..557ccf8 100644
--- a/gcc/testsuite/c-c++-common/diagnostic-format-json-2.c
+++ b/gcc/testsuite/c-c++-common/diagnostic-format-json-2.c
@@ -10,6 +10,7 @@
 /* { dg-regexp "\"kind\": \"warning\"" } */
 /* { dg-regexp "\"message\": \"#warning message\"" } */
 /* { dg-regexp "\"option\": \"-Wcpp\"" } */
+/* { dg-regexp "\"option_url\": \"https:\[^\n\r\"\]*#index-Wcpp\"" } */
 
 /* { dg-regexp "\"caret\": \{" } */
 /* { dg-regexp "\"file\": \"\[^\n\r\"\]*diagnostic-format-json-2.c\"" } */
diff --git a/gcc/testsuite/c-c++-common/diagnostic-format-json-3.c b/gcc/testsuite/c-c++-common/diagnostic-format-json-3.c
index 1c54eca..378205c 100644
--- a/gcc/testsuite/c-c++-common/diagnostic-format-json-3.c
+++ b/gcc/testsuite/c-c++-common/diagnostic-format-json-3.c
@@ -10,6 +10,7 @@
 /* { dg-regexp "\"kind\": \"error\"" } */
 /* { dg-regexp "\"message\": \"#warning message\"" } */
 /* { dg-regexp "\"option\": \"-Werror=cpp\"" } */
+/* { dg-regexp "\"option_url\": \"https:\[^\n\r\"\]*#index-Wcpp\"" } */
 
 /* { dg-regexp "\"caret\": \{" } */
 /* { dg-regexp "\"file\": \"\[^\n\r\"\]*diagnostic-format-json-3.c\"" } */
diff --git a/gcc/testsuite/c-c++-common/diagnostic-format-json-4.c b/gcc/testsuite/c-c++-common/diagnostic-format-json-4.c
index 1c3b034..2738be6 100644
--- a/gcc/testsuite/c-c++-common/diagnostic-format-json-4.c
+++ b/gcc/testsuite/c-c++-common/diagnostic-format-json-4.c
@@ -30,13 +30,12 @@ int test (void)
 /* { dg-regexp "\"line\": 8" } */
 /* { dg-regexp "\"column\": 10" } */
 
-/* { dg-regexp "\"locations\": \[\[\{\}, \]*\]" } */
-
 /* The outer diagnostic.  */
 
 /* { dg-regexp "\"kind\": \"warning\"" } */
 /* { dg-regexp "\"message\": \"this 'if' clause does not guard...\"" } */
 /* { dg-regexp "\"option\": \"-Wmisleading-indentation\"" } */
+/* { dg-regexp "\"option_url\": \"https:\[^\n\r\"\]*#index-Wmisleading-indentation\"" } */
 
 /* { dg-regexp "\"caret\": \{" } */
 /* { dg-regexp "\"file\": \"\[^\n\r\"\]*diagnostic-format-json-4.c\"" } */
@@ -48,6 +47,13 @@ int test (void)
 /* { dg-regexp "\"line\": 6" } */
 /* { dg-regexp "\"column\": 4" } */
 
+/* More from the nested diagnostic (we can't guarantee what order the
+   "file" keys are consumed).  */
+
+/* { dg-regexp "\"locations\": \[\[\{\}, \]*\]" } */
+
+/* More from the outer diagnostic.  */
+
 /* { dg-regexp "\"locations\": \[\[\{\}, \]*\]" } */
 
 /* { dg-regexp "\"children\": \[\[\{\}, \]*\]" } */