Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:

> Patch v3 still doesn't fix the problem. There are now pod2man errors
> that prevent correctly generating the man pages:
[...]
> (pod2man --center="GNU" --release="gcc-5.4.0" --date=2016-06-03 --section=7 gpl.pod > doc/gpl.7.T$$ && \
>         mv -f doc/gpl.7.T$$ doc/gpl.7) || \
>         (rm -f doc/gpl.7.T$$ && exit 1)
> pod2man: unable to format gpl.pod
> make: [Makefile:3061: doc/gpl.7] Error 1 (ignored)
> ../../gcc-5.4.0/gcc/cp/Make-lang.in:189: update target 'doc/g++.1' due to: doc/gcc.1
> cp doc/gcc.1 doc/g++.1
> rm gcc.pod
> make: Leaving directory '/tmp/guix-build-gcc-5.4.0.drv-0/build/gcc'
>

Apparently GCC < 6 required a patch to its texi2pod.pl script, which had
a syntax problem. The attached patch fixes this last problem. I could
successfully build GCC 5.4.0 by using a derived package for testing
(otherwise it would trigger a world rebuild which was never ending of my
lesser machine).

Here's the patch used to test it:

--8<---------------cut here---------------start------------->8---
 gnu/packages/gcc.scm                        | 21 +++++++++++++++++++++
 gnu/packages/patches/gcc-fix-texi2pod.patch | 19 +++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 gnu/packages/patches/gcc-fix-texi2pod.patch

diff --git a/gnu/packages/gcc.scm b/gnu/packages/gcc.scm
index 7870d4513..320201b9c 100644
--- a/gnu/packages/gcc.scm
+++ b/gnu/packages/gcc.scm
@@ -395,6 +395,27 @@ Go.  It also includes runtime support libraries for these languages.")
     ;; `(("isl" ,isl)
     ;;   ,@(package-inputs gcc-4.7)))))
 
+(define-public gcc-5-dev
+  (package (inherit gcc-5)
+    (name "gcc-dev")
+    (version "5.4.0-dev")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "mirror://gnu/gcc/gcc-"
+                                  version "/gcc-" version ".tar.bz2"))
+              (sha256
+               (base32
+                "0fihlcy5hnksdxk0sn6bvgnyq8gfrgs8m794b1jxwd1dxinzg3b0"))
+              (patches (search-patches "gcc-arm-bug-71399.patch"
+                                       "gcc-strmov-store-file-names.patch"
+                                       "gcc-asan-powerpc-missing-include.patch"
+                                       "gcc-5.0-libvtv-runpath.patch"
+                                       "gcc-5-source-date-epoch-1.patch"
+                                       "gcc-5-source-date-epoch-2.patch"
+                                       "gcc-fix-texi2pod.patch"))))
+    (native-inputs `(("perl" ,perl)   ;for manpages
+                     ("texinfo" ,texinfo)))))
+
 (define-public gcc-6
   (package
     (inherit gcc-5)
diff --git a/gnu/packages/patches/gcc-fix-texi2pod.patch b/gnu/packages/patches/gcc-fix-texi2pod.patch
new file mode 100644
index 000000000..28bd56a38
--- /dev/null
+++ b/gnu/packages/patches/gcc-fix-texi2pod.patch
@@ -0,0 +1,19 @@
+This patch was taken from the official GCC git repository.
+X-Git-Url: https://gcc.gnu.org/git/?p=gcc.git;a=blobdiff_plain;f=contrib%2Ftexi2pod.pl;h=91bdbb5cea933d0381f2924ab94490fca31d5800;hp=eba1bcaa3cffa78b46030b219d04fe7d68367658;hb=67b56c905078d49d3e4028085e5cb1e1fb87a8aa;hpb=2f508a78310caab123e9794d3dcfe41f2769449b
+
+It fixes a defect in the contrib/texi2pod.pl script that prevented generating
+manual pages. It was corrected in the GCC 6.X series.
+
+diff --git a/contrib/texi2pod.pl b/contrib/texi2pod.pl
+index eba1bca..91bdbb5 100755
+--- a/contrib/texi2pod.pl
++++ b/contrib/texi2pod.pl
+@@ -316,7 +316,7 @@ while(<$inf>) {
+ 	@columns = ();
+ 	for $column (split (/\s*\@tab\s*/, $1)) {
+ 	    # @strong{...} is used a @headitem work-alike
+-	    $column =~ s/^\@strong{(.*)}$/$1/;
++	    $column =~ s/^\@strong\{(.*)\}$/$1/;
+ 	    push @columns, $column;
+ 	}
+ 	$_ = "\n=item ".join (" : ", @columns)."\n";
--8<---------------cut here---------------end--------------->8---

I could then build gcc-dev and verify that the man pages gcc and cpp
were working correctly in an environment instantiated using:

--8<---------------cut here---------------start------------->8---
./pre-inst-env guix environment --pure --ad-hoc gcc-dev man-db
--8<---------------cut here---------------end--------------->8---

The complete patch is attached; it should be good for core-updates.

Thank you,

Maxim