[gcc r14-10007] DOCUMENTATION_ROOT_URL vs. release branches [PR114738]

[gcc r14-10007] DOCUMENTATION_ROOT_URL vs. release branches [PR114738]

[Jakub Jelinek]

https://gcc.gnu.org/g:57056146f4ffc5ea347c03e37e1e2c7cd99261d0

commit r14-10007-g57056146f4ffc5ea347c03e37e1e2c7cd99261d0
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Apr 17 16:17:22 2024 +0200

    DOCUMENTATION_ROOT_URL vs. release branches [PR114738]
    
    Starting with GCC 14 we have the nice URLification of the options printed
    in diagnostics, say for in
    test.c:4:23: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long int’ [-Wformat=]
    the -Wformat= is underlined in some terminals and hovering on it shows
    https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wformat
    link.
    
    This works nicely on the GCC trunk, where the online documentation is
    regenerated every day from a cron job and more importantly, people rarely
    use the trunk snapshots for too long, so it is unlikely that further changes
    in the documentation will make too many links stale, because users will
    simply regularly update to newer snapshots.
    
    I think it doesn't work properly on release branches though.
    Some users only use the relased versions (i.e. MAJOR.MINOR.0) from tarballs
    but can use them for a couple of years, others use snapshots from the
    release branches, but again they could be in use for months or years and
    the above mentioned online docs which represent just the GCC trunk might
    diverge significantly.
    
    Now, for the relases we always publish also online docs for the release,
    which unlike the trunk online docs will not change further, under
    e.g.
    https://gcc.gnu.org/onlinedocs/gcc-14.1.0/gcc/Warning-Options.html#index-Wformat
    or
    https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/Warning-Options.html#index-Wformat
    etc.
    
    So, I think at least for the MAJOR.MINOR.0 releases we want to use
    URLs like above rather than the trunk ones and we can use the same process
    of updating *.opt.urls as well for that.
    
    For the snapshots from release branches, we don't have such docs.
    One option (implemented in the patch below for the URL printing side) is
    point to the MAJOR.MINOR.0 docs even for MAJOR.MINOR.1 snapshots.
    Most of the links will work fine, for options newly added on the release
    branches (rare thing but still happens) can have until the next release
    no URLs for them and get them with the next point release.
    The question is what to do about make regenerate-opt-urls for the release
    branch snapshots.  Either just document that users shouldn't
    make regenerate-opt-urls on release branches (and filter out *.opt.urls
    changes from their commits), add make regenerate-opt-urls task be RM
    responsibility before making first release candidate from a branch and
    adjust the autoregen CI to know about that.  Or add a separate goal
    which instead of relying on make html created files would download
    copy of the html files from the last release from web (kind of web
    mirroring the https://gcc.gnu.org/onlinedocs/gcc-14.1.0/ subtree locally)
    and doing regenerate-opt-urls on top of that?  But how to catch the
    point when first release candidate is made and we want to update to
    what will be the URLs once the release is made (but will be stale URLs
    for a week or so)?
    
    Another option would be to add to cron daily regeneration of the online
    docs for the release branches.  I don't think that is a good idea though,
    because as I wrote earlier, not all users update to the latest snapshot
    frequently, so there can be users that use gcc 13.1.1 20230525 for months
    or years, and other users which use gcc 13.1.1 20230615 for years etc.
    
    Another question is what is most sensible for users who want to override
    the default root and use the --with-documentation-root-url= configure
    option.  Do we expect them to grab the whole onlinedocs tree or for release
    branches at least include gcc-14.1.0/ subdirectory under the root?
    If so, the patch below deals with that.  Or should we just change the
    default documentation root url, so if user doesn't specify
    --with-documentation-root-url= and we are on a release branch, default that
    to https://gcc.gnu.org/onlinedocs/gcc-14.1.0/ or
    https://gcc.gnu.org/onlinedocs/gcc-14.2.0/ etc. and don't add any infix in
    get_option_url/make_doc_url, but when people supply their own, let them
    point to the root of the tree which contains the right docs?
    Then such changes would go into gcc/configure.ac, some case based on
    "$gcc_version", from that decide if it is a release branch or trunk.
    
    2024-04-17  Jakub Jelinek  <jakub@redhat.com>
    
            PR other/114738
            * opts.cc (get_option_url): On release branches append
            gcc-MAJOR.MINOR.0/ after DOCUMENTATION_ROOT_URL.
            * gcc-urlifier.cc (gcc_urlifier::make_doc_url): Likewise.

Diff:
---
 gcc/gcc-urlifier.cc | 12 +++++++++++-
 gcc/opts.cc         | 14 +++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/gcc/gcc-urlifier.cc b/gcc/gcc-urlifier.cc
index be6459e8d7c..ff8c3f65ac5 100644
--- a/gcc/gcc-urlifier.cc
+++ b/gcc/gcc-urlifier.cc
@@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gcc-urlifier.h"
 #include "opts.h"
 #include "options.h"
+#include "diagnostic-core.h"
 #include "selftest.h"
 
 namespace {
@@ -208,7 +209,16 @@ gcc_urlifier::make_doc_url (const char *doc_url_suffix)
   if (!doc_url_suffix)
     return nullptr;
 
-  return concat (DOCUMENTATION_ROOT_URL, doc_url_suffix, nullptr);
+  char infix[32];
+  /* On release branches, append to DOCUMENTATION_ROOT_URL the
+     subdirectory with documentation of the latest release made
+     from the branch.  */
+  if (BUILDING_GCC_MINOR != 0 && BUILDING_GCC_PATCHLEVEL <= 1U)
+    sprintf (infix, "gcc-%u.%u.0/",
+	     BUILDING_GCC_MAJOR, BUILDING_GCC_MINOR);
+  else
+    infix[0] = '\0';
+  return concat (DOCUMENTATION_ROOT_URL, infix, doc_url_suffix, nullptr);
 }
 
 } // anonymous namespace
diff --git a/gcc/opts.cc b/gcc/opts.cc
index 3333600e0ea..a90dc57f8b5 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -3761,7 +3761,19 @@ get_option_url (const diagnostic_context *,
     {
       label_text url_suffix = get_option_url_suffix (option_index, lang_mask);
       if (url_suffix.get ())
-	return concat (DOCUMENTATION_ROOT_URL, url_suffix.get (), nullptr);
+	{
+	  char infix[32];
+	  /* On release branches, append to DOCUMENTATION_ROOT_URL the
+	     subdirectory with documentation of the latest release made
+	     from the branch.  */
+	  if (BUILDING_GCC_MINOR != 0 && BUILDING_GCC_PATCHLEVEL <= 1U)
+	    sprintf (infix, "gcc-%u.%u.0/",
+		     BUILDING_GCC_MAJOR, BUILDING_GCC_MINOR);
+	  else
+	    infix[0] = '\0';
+	  return concat (DOCUMENTATION_ROOT_URL, infix, url_suffix.get (),
+			 nullptr);
+	}
     }
 
   return nullptr;