GCC 15 fails to install

[tobbi]

Output of brew config

% brew config
HOMEBREW_VERSION: 4.6.8-15-gbd57ad8
ORIGIN: https://github.com/Homebrew/brew
HEAD: bd57ad891d076c9854f1b3be3bf55523f3549998
Last commit: 6 hours ago
Branch: main
Core tap HEAD: fbbdae0bb3ed579cd05d650ac211e4b718cd3379
Core tap last commit: 3 hours ago
Core tap JSON: 03 Sep 20:35 UTC
Core cask tap HEAD: 255bd099555e9d6e06472c6adab0170586e10b47
Core cask tap last commit: 3 hours ago
Core cask tap JSON: 03 Sep 20:35 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.RW8BSPOSbM/org.xquartz:0
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 8
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.4.5 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.4.5/bin/ruby
CPU: octa-core 64-bit ivybridge
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Volumes/Development/Xcode.app/Contents/Developer/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 12.7.6-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: 14.2 => /Volumes/Development/Xcode.app/Contents/Developer

Output of brew doctor

% brew doctor
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  gstreamer-runtime
  wine@devel

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  python-flit-core

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  icu4c@75
  icu4c@76
  node@18
  openssl@1.1
  protobuf@21
  tinyxml

Warning: You have booted macOS using OpenCore Legacy Patcher.
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You can report Tier 2 unrelated issues to Homebrew/* repositories!
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Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected header files:
  /usr/local/include/node/*
  /usr/local/include/qemu-plugin.h

Warning: You have unlinked kegs in your Cellar.
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those kegs to fail to run properly once built. Run `brew link` on these:
  qt@4
  node

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Description of issue

I can't install the latest version of gcc on my machine.

I keep getting this error:

clang++ -std=c++14 -c  -DBASEVER="\"15.1.0\"" -DDATESTAMP="\"\"" -DREVISION="\"\"" -DDEVPHASE="\"\"" -DPKGVERSION="\"(Homebrew GCC 15.1.0) \"" -DBUGURL="\"<https://github.com/Homebrew/homebrew-core/issues>\"" -g -DIN_GCC   -fno-strict-aliasing -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-error=narrowing -Wwrite-strings -Wcast-qual -Wno-format -Wmissing-format-attribute -Wconditionally-supported -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings  -DHAVE_CONFIG_H  -DGENERATOR_FILE -I. -Ibuild -I../../gcc -I../../gcc/build -I../../gcc/../include  -I../../gcc/../libcpp/include  \
	-o build/genversion.o ../../gcc/genversion.cc
../../gcc/doc//extend.texi:10002: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//extend.texi:10682: First argument to cross-reference may not be empty.
../../gcc/doc//extend.texi:10704: First argument to cross-reference may not be empty.
../../gcc/doc//extend.texi:12572: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//extend.texi:12576: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//gcov.texi:1080: @anchor expected braces.
../../gcc/doc//gcov.texi:1080: ` {gcov prime paths example}
When you com...' is too long for expansion; not expanded.
../../gcc/doc//gcov.texi:1080: @anchor missing close brace.
../../gcc/doc//gcov.texi:112: Next reference to nonexistent node `Gcov and Optimization' (perhaps incorrect sectioning?).
../../gcc/doc//gcov.texi:44: Menu reference to nonexistent node `Freestanding Environments' (perhaps incorrect sectioning?).
../../gcc/doc//gcov.texi:43: Menu reference to nonexistent node `Cross-profiling' (perhaps incorrect sectioning?).
../../gcc/doc//gcov.texi:42: Menu reference to nonexistent node `Gcov Data Files' (perhaps incorrect sectioning?).
../../gcc/doc//gcov.texi:41: Menu reference to nonexistent node `Gcov and Optimization' (perhaps incorrect sectioning?).
../../gcc/doc//invoke.texi:17655: Cross reference to nonexistent node `Cross-profiling' (perhaps incorrect sectioning?).
../../gcc/doc//invoke.texi:17642: Cross reference to nonexistent node `gcov prime paths example' (perhaps incorrect sectioning?).
makeinfo: Removing output file `doc/gcc.info' due to errors; use --force to preserve.
gmake[3]: *** [Makefile:3787: doc/gcc.info] Error 1
gmake[3]: *** Waiting for unfinished jobs....
/bin/sh ../../gcc/../move-if-change tmp-optionlist optionlist
echo timestamp > s-options
rm gcc.pod
gmake[3]: Leaving directory '/private/tmp/gcc-20250903-23571-3w5a10/gcc-15.1.0/build/gcc'
gmake[2]: *** [Makefile:5073: all-stage1-gcc] Error 2
gmake[2]: Leaving directory '/private/tmp/gcc-20250903-23571-3w5a10/gcc-15.1.0/build'
gmake[1]: *** [Makefile:24631: stage1-bubble] Error 2
gmake[1]: Leaving directory '/private/tmp/gcc-20250903-23571-3w5a10/gcc-15.1.0/build'
gmake: *** [Makefile:1101: all] Error 2

HOMEBREW_VERSION: 4.6.8-15-gbd57ad8
ORIGIN: https://github.com/Homebrew/brew
HEAD: bd57ad891d076c9854f1b3be3bf55523f3549998
Last commit: 3 hours ago
Branch: main
Core tap HEAD: fbbdae0bb3ed579cd05d650ac211e4b718cd3379
Core tap last commit: 35 minutes ago
Core tap JSON: 03 Sep 20:35 UTC
Core cask tap HEAD: 255bd099555e9d6e06472c6adab0170586e10b47
Core cask tap last commit: 37 minutes ago
Core cask tap JSON: 03 Sep 20:35 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.RW8BSPOSbM/org.xquartz:0
HOMEBREW_MAKE_JOBS: 8
HOMEBREW_NO_BOOTSNAP: set
HOMEBREW_NO_INSTALL_FROM_API: set
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.4.5 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.4.5/bin/ruby
CPU: octa-core 64-bit ivybridge
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Volumes/Development/Xcode.app/Contents/Developer/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 12.7.6-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: 14.2 => /Volumes/Development/Xcode.app/Contents/Developer

HOMEBREW_CC: clang
HOMEBREW_CXX: clang++
MAKEFLAGS: -j8
CMAKE_PREFIX_PATH: /usr/local
CMAKE_INCLUDE_PATH: /Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk/System/Library/Frameworks/OpenGL.framework/Versions/Current/Headers
CMAKE_LIBRARY_PATH: /Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries
PKG_CONFIG_PATH: /usr/local/opt/gmp/lib/pkgconfig:/usr/local/opt/isl/lib/pkgconfig:/usr/local/opt/mpfr/lib/pkgconfig:/usr/local/opt/lz4/lib/pkgconfig:/usr/local/opt/xz/lib/pkgconfig:/usr/local/opt/zstd/lib/pkgconfig
PKG_CONFIG_LIBDIR: /usr/lib/pkgconfig:/usr/local/Homebrew/Library/Homebrew/os/mac/pkgconfig/12
HOMEBREW_MAKE_JOBS: 8
HOMEBREW_GIT: git
HOMEBREW_SDKROOT: /Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk
ACLOCAL_PATH: /usr/local/share/aclocal
PATH: /usr/local/Homebrew/Library/Homebrew/shims/mac/super:/usr/local/opt/lz4/bin:/usr/local/opt/xz/bin:/usr/local/opt/zstd/bin:/usr/local/opt/make/bin:/usr/bin:/bin:/usr/sbin:/sbin

Full log:
02.gmake.log

[ZhongRuoyu]

GCC 15.1 docs failed to build with old makeinfo and this was already fixed upstream. You can try applying the following two patches.

• gcc-mirror/gcc@e1a2af2
• gcc-mirror/gcc@8b435e1

PS: An update that fixes a performance issue has just been applied to GCC (Homebrew/homebrew-core#235988). You may want to update your local tap in case you haven't.

[tobbi]

I'm gonna do that and check again. By the way: How would one update makeinfo? Is that also something that's installed through homebrew?

[ZhongRuoyu]

How would one update makeinfo? Is that also something that's installed through homebrew?

That's bundled with macOS (as part of the texinfo package) and available at /usr/bin/makeinfo. It was removed since macOS Sequoia 13. (We seem to be pulling the texinfo dependency indirectly so our official builds still work.) You can also work around this by adding a direct dependency depends_on "texinfo" => :build.

[tobbi]

Alright, was just curious. I applied those two patches mentioned above and it appears to be building for now. Will close this thread once it's done.

[tobbi]

Okay, I'm getting a new error:
02.gmake.log

It's really hard to read as the output is so mangled. Maybe this?

checking whether time.h and sys/time.h may both be included... ../../gcc/doc//extend.texi:10002: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/fortran//intrinsic.texi:14978: Unknown command `cindex,'.
../../gcc/doc//extend.texi:12572: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//extend.texi:12576: warning: `.' or `,' must follow @xref, not `)'.
makeinfo: Removing output file `doc/gfortran.info' due to errors; use --force to preserve.
gmake[3]: *** [../../gcc/fortran/Make-lang.in:203: doc/gfortran.info] Error 1
gmake[3]: *** Waiting for unfinished jobs....

[ZhongRuoyu]

Seems like another makeinfo issue. At this point I would try switching over to Homebrew texinfo instead.

[tobbi]

Alright, it's building again. Can the formula itself check for an outdated version of texinfo and install the homebrew one in that case? Although I'm aware I'm using a not-supported version of OS X.

[ZhongRuoyu]

Alright, it's building again. Can the formula itself check for an outdated version of texinfo and install the homebrew one in that case? Although I'm aware I'm using a not-supported version of OS X.

Yes, it's possible and already used in some formulae like gdb:

on_system :linux, macos: :ventura_or_newer do
  depends_on "texinfo" => :build
end

Though, I'm not clear why the info docs are even being built, because according to GCC docs:

Releases contain Info documentation pre-built for the unmodified documentation in the release.

So it sounds like the docs don't actually need to be (re-)built.

[tobbi]

Yeah, I tried to disable building the docs (and according to the GCC IRC channel, there's supposed to be a configure flag that can be passed) but I couldn't find one.

[tobbi]

The GCC build ran through successfully. I'm closing this.

[Izumi-kun]

I have the same issue with building gcc 15.2.0.

../../gcc/fortran/gfortran.texi:1842: First argument to cross-reference may not be empty.
../../gcc/fortran/gfortran.texi:1903: First argument to cross-reference may not be empty.
../../gcc/doc//extend.texi:10002: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//extend.texi:12572: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/doc//extend.texi:12576: warning: `.' or `,' must follow @xref, not `)'.
../../gcc/fortran//intrinsic.texi:14978: Unknown command `cindex,'.

texinfo installed from Homebrew but it doesn't help.

$ brew info texinfo
==> texinfo: stable 7.2
Official documentation format of the GNU project
https://www.gnu.org/software/texinfo/
Installed
/usr/local/Cellar/texinfo/7.2 (561 files, 13.3MB) *
  Built from source on 2025-10-13 at 21:17:05
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/t/texinfo.rb

Full log: 02.gmake.log

[ZhongRuoyu]

Did you edit the gcc formula to depend on Homebrew texinfo?

[Izumi-kun]

My mistake. The build is successful now after I updated the formula. Thank you!