Duplicate -lgcc flags in linker command with GCC 13.2.0 on macOS

[TahaAkhlaq]

brew gist-logs <formula> link OR brew config AND brew doctor output

`brew config` Output: 
HOMEBREW_VERSION: 4.2.19
ORIGIN: https://github.com/Homebrew/brew
HEAD: 54bea636b41f7953c01a7da5f488f08c1b42ffd1
Last commit: 7 days ago
Core tap JSON: 29 Apr 04:13 UTC
Core cask tap JSON: 29 Apr 04:13 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_BROWSER: /Users/taha/.vscode-server/cli/servers/Stable-31c37ee8f63491495ac49e43b8544550fbae4533/server/bin/helpers/browser.sh
HOMEBREW_CASK_OPTS: []
HOMEBREW_EDITOR: code --wait
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 3.1.4 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.1.4/bin/ruby
CPU: octa-core 64-bit arm_blizzard_avalanche
Clang: 15.0.0 build 1500
Git: 2.44.0 => /opt/homebrew/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 14.3.1-arm64
CLT: 15.1.0.0.1.1700200546
Xcode: 15.3
Rosetta 2: false

`brew doctor` Output: 
Your system is ready to brew

Verification

• My brew doctor output says Your system is ready to brew. and am still able to reproduce my issue.
• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.
• I searched for recent similar issues at https://github.com/Homebrew/homebrew-core/issues?q=is%3Aissue and found no duplicates.

What were you trying to do (and why)?

I was trying to compile a simple C++ project using GCC installed via Homebrew on macOS. My goal was to use the latest GCC for my development work, but I encountered an issue with duplicate library flags during the linking phase, which I believe might be a configuration error or a bug.

What happened (include all command output)?

I am experiencing an issue where the ld linker command automatically includes the -lgcc library twice when compiling a C++ project using GCC 13.2.0 installed via Homebrew on macOS. This results in a warning about ignoring duplicate libraries, which I'd like to resolve or understand.

Command Used:
g++ project3.cpp -o project3

The linker command includes -lgcc twice, resulting in a warning:
ld: warning: ignoring duplicate libraries: '-lgcc'

Verbose output indicated that -lgcc is being linked twice in the linker command automatically generated by GCC.

Verbose Output
(Including a brief snippet of the verbose output where the duplicate -lgcc is evident)
.o -lstdc++ -lemutls_w -lgcc -lSystem -lgcc -no_compact_unwind -rpath

What did you expect to happen?

I expected the linker command not to include duplicate library flags, which should avoid the warning about ignoring duplicate libraries. Ideally, the build process should be clean without such warnings, ensuring that the linker configuration is optimal and error-free.

Step-by-step reproduction instructions (by running brew commands)

**Steps to Reproduce**
1. Install GCC via Homebrew using `brew install gcc`.
2. Compile any simple C++ program with `g++ [file].cpp -o [file]`.
3. Observe the linker warning about duplicate `-lgcc` flags.

Other:
**System Information**
- **macOS Version**: Sonoma (Version 14)
- **Homebrew Version**: Homebrew 4.2.19
- **GCC Version**: 13.2.0: g++-13 (Homebrew GCC 13.2.0) 13.2.0

**Additional Information**
- I have checked my environment settings and there are no configurations explicitly adding `-lgcc` multiple times.
- The issue seems to be internal to the way GCC is configured or how it interacts with the system linker.


Thank you for any help or insight you can provide!

[ZhongRuoyu]

Can you try updating your Command Line Tools? See also: https://github.com/orgs/Homebrew/discussions/4794

[TahaAkhlaq]

Thank you for your response. The Command Line Tools are updated. Also, thank you for linking the discussion!

[fxcoudert]

The warning is harmless, and the fix has been made upstream.