[committed] Fix warning URLs for Fortran and analyzer [PR 92830]

diff --git a/gcc/configure.ac b/gcc/configure.ac
index fdee9ea587c..cd62312b813 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -982,7 +982,7 @@  AC_ARG_WITH(documentation-root-url,
       *)   DOCUMENTATION_ROOT_URL="$withval"
 	   ;;
      esac],
-     DOCUMENTATION_ROOT_URL="https://gcc.gnu.org/onlinedocs/gcc/"
+     DOCUMENTATION_ROOT_URL="https://gcc.gnu.org/onlinedocs/"
 )
 AC_SUBST(DOCUMENTATION_ROOT_URL)
 
diff --git a/gcc/opts.c b/gcc/opts.c
index d4df8627bf7..c212a1a57dc 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -32,6 +32,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "spellcheck.h"
 #include "opt-suggestions.h"
 #include "diagnostic-color.h"
+#include "selftest.h"
 
 static void set_Wstrict_aliasing (struct gcc_options *opts, int onoff);
 
@@ -3128,6 +3129,42 @@  option_name (diagnostic_context *context, int option_index,
     return NULL;
 }
 
+/* Get the page within the documentation for this option.  */
+
+static const char *
+get_option_html_page (int option_index)
+{
+  const cl_option *cl_opt = &cl_options[option_index];
+
+  /* Analyzer options are on their own page.  */
+  if (strstr(cl_opt->opt_text, "analyzer-"))
+    return "gcc/Static-Analyzer-Options.html";
+
+#ifdef CL_Fortran
+  if (cl_opt->flags & CL_Fortran)
+    {
+      switch (option_index)
+	{
+	default:
+	  /* Most Fortran warnings are documented on this page.  */
+	  return "gfortran/Error-and-Warning-Options.html";
+
+	case OPT_Wdate_time:
+	case OPT_Wconversion:
+	case OPT_Wconversion_extra:
+	case OPT_Wmissing_include_dirs:
+	case OPT_Wopenmp_simd:
+	  /* These warnings are marked in fortran/lang.opt as
+	     "Documented in C" and thus use the common
+	     Warning-Options page below.  */
+	  break;
+	}
+    }
+#endif
+
+  return "gcc/Warning-Options.html";
+}
+
 /* Return malloced memory for a URL describing the option OPTION_INDEX
    which enabled a diagnostic (context CONTEXT).  */
 
@@ -3135,16 +3172,50 @@  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",
+    return concat (/* DOCUMENTATION_ROOT_URL should be supplied via -D by
+		      the Makefile (see --with-documentation-root-url), and
+		      should have a trailing slash.  */
+		   DOCUMENTATION_ROOT_URL,
+
+		   /* get_option_html_page will return something like
+		      "gcc/Warning-Options.html".  */
+		   get_option_html_page (option_index),
+
+		   /* 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".  */
 		   "#index", cl_options[option_index].opt_text,
 		   NULL);
   else
     return NULL;
 }
+
+#if CHECKING_P
+
+namespace selftest {
+
+/* Verify that get_option_html_page works as expected.  */
+
+static void
+test_get_option_html_page ()
+{
+  ASSERT_STREQ (get_option_html_page (OPT_Wcpp), "gcc/Warning-Options.html");
+  ASSERT_STREQ (get_option_html_page (OPT_Wanalyzer_double_free),
+	     "gcc/Static-Analyzer-Options.html");
+#ifdef CL_Fortran
+  ASSERT_STREQ (get_option_html_page (OPT_Wline_truncation),
+		"gfortran/Error-and-Warning-Options.html");
+#endif
+}
+
+/* Run all of the selftests within this file.  */
+
+void
+opts_c_tests ()
+{
+  test_get_option_html_page ();
+}
+
+} // namespace selftest
+
+#endif /* #if CHECKING_P */
diff --git a/gcc/selftest-run-tests.c b/gcc/selftest-run-tests.c
index d47e92862f1..f0a81d43fd6 100644
--- a/gcc/selftest-run-tests.c
+++ b/gcc/selftest-run-tests.c
@@ -73,6 +73,7 @@  selftest::run_tests ()
   typed_splay_tree_c_tests ();
   unique_ptr_tests_cc_tests ();
   opt_proposer_c_tests ();
+  opts_c_tests ();
   json_cc_tests ();
   cgraph_c_tests ();
   optinfo_emit_json_cc_tests ();
diff --git a/gcc/selftest.h b/gcc/selftest.h
index df98e0b5f12..5cffa13aedd 100644
--- a/gcc/selftest.h
+++ b/gcc/selftest.h
@@ -243,6 +243,7 @@  extern void input_c_tests ();
 extern void json_cc_tests ();
 extern void opt_problem_cc_tests ();
 extern void optinfo_emit_json_cc_tests ();
+extern void opts_c_tests ();
 extern void ordered_hash_map_tests_cc_tests ();
 extern void predict_c_tests ();
 extern void pretty_print_c_tests ();