RFR: 8351322: Parameterize link option for pthreads

[Magnus Ihse Bursie]

On Thu, 6 Mar 2025 17:28:10 GMT, snake66 <duke at openjdk.org> wrote:

>> make/autoconf/libraries.m4 line 142:
>> 
>>> 140:   # Threading library
>>> 141:   if test "x$OPENJDK_TARGET_OS" = xlinux || test "x$OPENJDK_TARGET_OS" = xaix; then
>>> 142:     BASIC_JVM_LIBS="$BASIC_JVM_LIBS $(LIBPTHREAD)"
>> 
>> If you specifically need this to be resolved in the makefile rather than here, then please add a comment explaining why, otherwise use a shell script variable reference.
>> 
>> Suggestion:
>> 
>>     BASIC_JVM_LIBS="$BASIC_JVM_LIBS $LIBPTHREAD"
>
> @erikj79 There will be a later patch to libraries.m4 that sets the variable based on the target platform, and then populates the `LIBPTHREAD` variable in spec.gmk. (https://github.com/openjdk/jdk/pull/23930/files#diff-56172cd2ec5804a5f764a6d0d5970da6144b024a06e008571f9822b2dc83cc36R147) That means the parenthesis should stay, right?

I'm not sure what you mean now. The link is to this very patch, which does what you describe -- sets LIBPTHREAD according to OS and stores it in spec.gmk.

And no, the paranthesis should not stay. If you keep them, the variable will be re-evaluated in make every time BASIC_JVM_LIBS is evaluated. That is not needed; by dropping the parenthesis the actual value to be used will be inserted as a string constant. Which is what we want, since we know the value at configure time.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23930#discussion_r1983853576