diff mbox series

DOCUMENTATION_ROOT_URL vs. release branches [PR114738]

Message ID Zh+vmxuH7V5ou10l@tucnak
State New
Headers show
Series DOCUMENTATION_ROOT_URL vs. release branches [PR114738] | expand

Commit Message

Jakub Jelinek April 17, 2024, 11:16 a.m. UTC
Hi!

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.


	Jakub

Comments

Richard Biener April 17, 2024, 12:44 p.m. UTC | #1
On Wed, Apr 17, 2024 at 1:17 PM Jakub Jelinek <jakub@redhat.com> wrote:
>
> Hi!
>
> 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.

I think this patch is sensible and an improvement over the current situation.
I guess we'll have to see how things evolve on the branch and adapt.

So, OK.

Thanks,
Richard.

> 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.
>
> --- gcc/opts.cc.jj      2024-01-05 08:35:13.600828652 +0100
> +++ gcc/opts.cc 2024-04-17 12:03:10.961525141 +0200
> @@ -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;
> --- gcc/gcc-urlifier.cc.jj      2024-01-10 17:15:31.851855587 +0100
> +++ gcc/gcc-urlifier.cc 2024-04-17 12:14:47.902706021 +0200
> @@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.
>  #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 *
>    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
>
>         Jakub
>
David Malcolm April 23, 2024, 3:40 p.m. UTC | #2
On Wed, 2024-04-17 at 13:16 +0200, Jakub Jelinek wrote:
> Hi!
> 
> 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.

That isn't new in GCC 14; we've provided the URLs for the option
guarding a warning since GCC 10, I think.  What's new is that we now
"urlify" any quoted text that mentions an option, and that the option
URLs are now based on the anchors in the generated HTML (and thus more
likely to be correct).

> 
> 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.

Would it make sense to instead update the default value in
gcc/configure.ac for DOCUMENTATION_ROOT_URL when branching or
releasing, from https://gcc.gnu.org/onlinedocs/ to
https://gcc.gnu.org/onlinedocs/gcc-MAJOR-MINOR.0/

?

Before this patch the DOCUMENTATION_ROOT_URL expresses the location of
a built texinfo html tree of docs, and the url suffixes express the
path within that tree.

As the patch is written, if a distributor overrides --with-
documentation-root-url= at configure time, then they need to mirror the
structure of our website on their website, which seems like a burden.



> 
> 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.

I think changing the default for DOCUMENTATION_ROOT_URL makes much more
sense.

Dave

> 
> 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.
> 
> --- gcc/opts.cc.jj      2024-01-05 08:35:13.600828652 +0100
> +++ gcc/opts.cc 2024-04-17 12:03:10.961525141 +0200
> @@ -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;
> --- gcc/gcc-urlifier.cc.jj      2024-01-10 17:15:31.851855587 +0100
> +++ gcc/gcc-urlifier.cc 2024-04-17 12:14:47.902706021 +0200
> @@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.
>  #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 *
>    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
> 
>         Jakub
>
Jakub Jelinek April 23, 2024, 3:45 p.m. UTC | #3
On Tue, Apr 23, 2024 at 11:40:55AM -0400, David Malcolm wrote:
> > 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.
> 
> Would it make sense to instead update the default value in
> gcc/configure.ac for DOCUMENTATION_ROOT_URL when branching or
> releasing, from https://gcc.gnu.org/onlinedocs/ to
> https://gcc.gnu.org/onlinedocs/gcc-MAJOR-MINOR.0/
> 
> ?
> 
> Before this patch the DOCUMENTATION_ROOT_URL expresses the location of
> a built texinfo html tree of docs, and the url suffixes express the
> path within that tree.
> 
> As the patch is written, if a distributor overrides --with-
> documentation-root-url= at configure time, then they need to mirror the
> structure of our website on their website, which seems like a burden.

Sure, that is doable (of course, it shouldn't be done by updating
gcc/configure.ac but by adjusting the default in there based on gcc_version,
I'll post a patch tomorrow).

Still, what do you think we should do on the release branches (recommend to
developers and check with the post-commit CI)?
No regeneration of *.urls except before doing a new release candidate,
or a different make goal that would grab html files from the web and
regenerate against that?

	Jakub
David Malcolm April 23, 2024, 11:07 p.m. UTC | #4
On Tue, 2024-04-23 at 17:45 +0200, Jakub Jelinek wrote:
> On Tue, Apr 23, 2024 at 11:40:55AM -0400, David Malcolm wrote:
> > > 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.
> > 
> > Would it make sense to instead update the default value in
> > gcc/configure.ac for DOCUMENTATION_ROOT_URL when branching or
> > releasing, from https://gcc.gnu.org/onlinedocs/ to
> > https://gcc.gnu.org/onlinedocs/gcc-MAJOR-MINOR.0/
> > 
> > ?
> > 
> > Before this patch the DOCUMENTATION_ROOT_URL expresses the location
> > of
> > a built texinfo html tree of docs, and the url suffixes express the
> > path within that tree.
> > 
> > As the patch is written, if a distributor overrides --with-
> > documentation-root-url= at configure time, then they need to mirror
> > the
> > structure of our website on their website, which seems like a
> > burden.
> 
> Sure, that is doable (of course, it shouldn't be done by updating
> gcc/configure.ac but by adjusting the default in there based on
> gcc_version,
> I'll post a patch tomorrow).

That sounds like a better approach; thanks.

> 
> Still, what do you think we should do on the release branches
> (recommend to
> developers and check with the post-commit CI)?

My hope is that the URL suffixes don't change: we shouldn't be adding
new command-line options on the release branches, and I'd hope that
texinfo doesn't change the generated anchors from run to run.

> No regeneration of *.urls except before doing a new release
> candidate,
> or a different make goal that would grab html files from the web and
> regenerate against that?

That sounds overcomplicated. 

If the anchors do change, it's fairly trivial to run "make regenerate-
opt-urls" locally, isn't it?

As mentioned above, I like the idea of having the
DOCUMENTATION_ROOT_URL express the location of a tree of docs built
with texinfo, and for the url suffixes to be relative to that.  We can
update the default in gcc/configure.ac for released branches, and drop
the logic from your previous patch.  So if a distributor wants to
upload their docs for a particular version to their own location,
they're responsible for providing a suitable value for  --with-
documentation-root-url= at configure time.

Or am I missing something here?

Dave
diff mbox series

Patch

--- gcc/opts.cc.jj	2024-01-05 08:35:13.600828652 +0100
+++ gcc/opts.cc	2024-04-17 12:03:10.961525141 +0200
@@ -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;
--- gcc/gcc-urlifier.cc.jj	2024-01-10 17:15:31.851855587 +0100
+++ gcc/gcc-urlifier.cc	2024-04-17 12:14:47.902706021 +0200
@@ -26,6 +26,7 @@  along with GCC; see the file COPYING3.
 #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 *
   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