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cli: fix undefined alloca() on CYGWIN#7022

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ethomson merged 1 commit into
libgit2:mainfrom
carlo-bramini:fix-cygwin-1
Jan 20, 2025
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cli: fix undefined alloca() on CYGWIN#7022
ethomson merged 1 commit into
libgit2:mainfrom
carlo-bramini:fix-cygwin-1

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@carlo-bramini
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I tried to build my libgit2-1.9.0 package for CYGWIN but I got an error.
This message appears when compiling:

[199/671] Building C object src/cli/CMakeFiles/git2_cli.dir/opt.c.o libgit2-1.9.0/src/cli/opt.c:
In function ‘cli_opt_parse’: libgit2-1.9.0/src/cli/opt.c:564:23: warning: implicit declaration of function ‘alloca’; did you mean ‘malloc’? [-Wimplicit-function-declaration]
  564 |         given_specs = alloca(sizeof(const cli_opt_spec *) * (args_len + 1));
      |                       ^~~~~~
      |                       malloc

and later the linker emits this error message:

[668/671] Linking C executable git2.exe
FAILED: git2.exe
/usr/x86_64-pc-cygwin/bin/ld: src/cli/CMakeFiles/git2_cli.dir/opt.c.o: in function `cli_opt_parse':
/usr/src/debug/libgit2-1.9.0-1/src/cli/opt.c:564:(.text+0xce3): undefined reference to `alloca' collect2: error: ld returned 1 exit status

The error is fixed by adding alloca.h to included headers.
Hopefully, opt.c already allows to add alloca.h for some platforms, so I just added an additional test for the preprocessor for checking if the target is CYGWIN.

I tried to build my libgit2-1.9.0 package for CYGWIN but I got an error. This message appears when compiling:

[199/671] Building C object src/cli/CMakeFiles/git2_cli.dir/opt.c.o
libgit2-1.9.0/src/cli/opt.c: In function ‘cli_opt_parse’:
libgit2-1.9.0/src/cli/opt.c:564:23: warning: implicit declaration of function ‘alloca’; did you mean ‘malloc’? [-Wimplicit-function-declaration]
  564 |         given_specs = alloca(sizeof(const cli_opt_spec *) * (args_len + 1));
      |                       ^~~~~~
      |                       malloc

and later the linker emits this error message:

[668/671] Linking C executable git2.exe
FAILED: git2.exe
/usr/x86_64-pc-cygwin/bin/ld: src/cli/CMakeFiles/git2_cli.dir/opt.c.o: in function `cli_opt_parse':
/usr/src/debug/libgit2-1.9.0-1/src/cli/opt.c:564:(.text+0xce3): undefined reference to `alloca'
collect2: error: ld returned 1 exit status

The error is fixed by adding alloca.h to included headers.
Hopefully, opt.c already allows to add alloca.h for some platforms, so I just added an additional test for the preprocessor for checking if the target is CYGWIN.
@ethomson ethomson merged commit 9046535 into libgit2:main Jan 20, 2025
@ethomson
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Thanks!

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2 participants