RFR: 8352284: EXTRA_CFLAGS incorrectly applied to BUILD_LIBJVM src/hotspot C++ source files [v2]

[Patrick Zhang]

On Sat, 22 Mar 2025 10:09:46 GMT, Patrick Zhang <qpzhang at openjdk.org> wrote:

>> Building jdk with `--with-extra-cflags='-Wno-incompatible-pointer-types'` triggers 1000+ warning messages like `cc1plus: warning: command-line option ‘-Wno-incompatible-pointer-types’ is valid for C/ObjC but not for C++`. 
>> 
>> The root cause is that `JVM_CFLAGS ` which contains both `EXTRA_CXXFLAGS` and `EXTRA_CFLAGS` when compiling `src/hotspot` C++ source files and building `BUILD_LIBJVM`.
>> 
>> This PR does:
>> 1. Not to append `EXTRA_CFLAGS` or `EXTRA_CXXFLAGS` into `JVM_CFLAGS` before calling `SetupJdkLibrary`, instead let `SetupCompilerFlags` accept and merge `EXTRA_CFLAGS` and `EXTRA_CXXFLAGS` passed from `SetupJdkLibrary` as parameters, so CPP compilation will only see `EXTRA_CXXFLAGS` as expected.
>> 2. Correct `PCH_COMMAND` to use `EXTRA_CXXFLAGS` as precompiled.hpp.gch should not be compiled with `EXTRA_CFLAGS`.
>> 3. Fixed `STATIC_LIB_CFLAGS` in `Flags.gmk` to `-DSTATIC_BUILD=1`, which was missed by [cbab40bc](https://github.com/openjdk/jdk/commit/cbab40bce45a2f58906be49c841178fa1dfd457e#diff-ab3ce05e795360030f19402fd0c2fad1dc1f7c5e7acc993cc4a2096cf31ccf40R114-R121) for the refactor of building static libs.
>> 
>> Tests: Passed jdk building on an AArch64 Linux system and tier1 sanity tests, also passed OpenJDK GHA Sanity Checks.
>
> Patrick Zhang has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Fixed a typo
>    
>    Signed-off-by: Patrick Zhang <patrick at os.amperecomputing.com>
>  - Added comments to describe why EXTRA_CFLAGS is excluded from JVM_CFLAGS
>    
>    Signed-off-by: Patrick Zhang <patrick at os.amperecomputing.com>
>  - Revert the changes of adding new params to SetupNativeCompilation
>    
>    Signed-off-by: Patrick Zhang <patrick at os.amperecomputing.com>

Hi @magicus , do you think my above clarifications regarding the unrelated code change and added comments acceptable, or do you still recommend removing those sections before merging? Thank you for confirming, and any advice on further changes.

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PR Comment: https://git.openjdk.org/jdk/pull/24115#issuecomment-2766136731