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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"On macOS, Configure script assumes that \"gcc\" is an alias for \"clang\", even if it really is GCC","articleBody":"# Your environment\r\n\r\n* MacOS 12.4\r\n\r\n# Bug report\r\n\r\nApologies if this is a known \"wontfix\" issue, I didn't see it mentioned in a search of past issues.\r\n\r\nThe `configure.ac` script assumes that `gcc` is actually `clang` on MacOS and uses Clang's `-fprofile-instr-generate` flag for PGO instead of GCC's `-fprofile-generate`, leading to build failure when PGO is turned on.\r\n\r\nSteps to reproduce on MacOS:\r\n\r\n```sh\r\nsudo port install gcc\r\n# or `brew install gcc`, same result\r\n\r\nCC='/opt/local/bin/gcc-mp-12' pyenv install --verbose 3.10.6\r\n```\r\n\r\nOutcome:\r\n\r\n```text\r\n...\r\ngcc-mp-12: error: unrecognized command-line option '-fprofile-instr-generate'; did you mean '-fprofile-generate'?\r\n...\r\n```\r\n\r\nThe problem is found here: https://github.com/python/cpython/blob/3.10/configure.ac#L1491-L1514\r\n```sh\r\ncase $CC in\r\n  *clang*)\r\n    # Any changes made here should be reflected in the GCC+Darwin case below\r\n    ...\r\n    ;;\r\n  *gcc*)\r\n    case $ac_sys_system in\r\n      Darwin*)\r\n        PGO_PROF_GEN_FLAG=\"-fprofile-instr-generate\"\r\n        PGO_PROF_USE_FLAG=\"-fprofile-instr-use=code.profclangd\"\r\n```\r\n\r\nMacOS (perhaps annoyingly) ships with `gcc` as an alias for `clang`, so the configure script sensibly assumes that `gcc` is actually `clang` and sets its options accordingly.\r\n\r\nHowever, that isn't always a correct assumption!\r\n\r\nPossible solutions:\r\n\r\n1. Check for the presence of `Apple clang` in the `$CC --version` output.\r\n2. Check that the absolute path of `$CC` is `/usr/bin/gcc`.","author":{"url":"https://github.com/gwerbin","@type":"Person","name":"gwerbin"},"datePublished":"2022-08-24T19:52:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/96249/cpython/issues/96249"}