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gh-109054: Don't use libatomic on cross-compilation#109211

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Merged
vstinner merged 1 commit into from
Sep 10, 2023
Merged

gh-109054: Don't use libatomic on cross-compilation #109211

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7 changes: 2 additions & 5 deletions configure
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7 changes: 4 additions & 3 deletions configure.ac
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Original file line numberDiff line numberDiff line change
Expand Up@@ -7007,9 +7007,10 @@ int main()
}
return 0; // all good
}
]])],[
ac_cv_libatomic_needed=no
],[ac_cv_libatomic_needed=yes],[ac_cv_libatomic_needed=yes])
]])],
[ac_cv_libatomic_needed=no], dnl build succeeded
[ac_cv_libatomic_needed=yes], dnl build failed
[ac_cv_libatomic_needed=no]) dnl cross compilation

@erlend-aaslanderlend-aaslandSep 11, 2023

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We could have used ac_cv_libatomic_needed=n/a for a more accurate result message.

@vstinnervstinnerSep 11, 2023

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Oh, I didn't know this value.

@erlend-aaslanderlend-aaslandSep 13, 2023

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Oh, I didn't know this value.

Actually, the value is up to you; it's not a magical GNU Autoconf value :) See docs for AC_CACHE_CHECK. The signature for that macro is:

AC_CACHE_CHECK (message, cache-id, commands-to-set-it)

Quoting the docs:

It calls AC_MSG_CHECKING for message, then AC_CACHE_VAL with the cache-id and commands arguments, and AC_MSG_RESULT with cache-id.

In out case, cache-id is ac_cv_libatomic_needed. Whatever we set it to will be displayed to the user at the end of the check (via the implicit AC_MSG_RESULT call). So if we set ac_cv_libatomic_needed to n/a, the user should see this when cross-compiling:

checking whether libatomic is needed by <pyatomic.h>... n/a

Currently, the user will see this when cross-compiling:

checking whether libatomic is needed by <pyatomic.h>... no

The "no" may lead the user to incorrectly assume that configure actually checked whether libatomic was needed (and that configure concluded it was not).

I think it may be worth it to adjust this message. What do you think?

@erlend-aaslanderlend-aaslandSep 13, 2023

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Oh, my suggestion is made moot by #109344

])

AS_VAR_IF([ac_cv_libatomic_needed], [yes],
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