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

1 files changed, 21 insertions, 0 deletions

diff --git a/gcc/opts.c b/gcc/opts.c
index 1070b9d..32869ca 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -3218,3 +3218,24 @@ option_name (diagnostic_context *context, int option_index,
   else
     return NULL;
 }
+
+/* Return malloced memory for a URL describing the option OPTION_INDEX
+   which enabled a diagnostic (context CONTEXT).  */
+
+char *
+get_option_url (diagnostic_context *, int option_index)
+{
+  if (option_index)
+    /* DOCUMENTATION_ROOT_URL should be supplied via -D by the Makefile
+       (see --with-documentation-root-url).
+
+       Expect an anchor of the form "index-Wfoo" e.g.
+       <a name="index-Wformat"></a>, and thus an id within
+       the URL of "#index-Wformat".  */
+    return concat (DOCUMENTATION_ROOT_URL,
+		   "Warning-Options.html",
+		   "#index", cl_options[option_index].opt_text,
+		   NULL);
+  else
+    return NULL;
+}