[vcpkg-tool] Add -DPIC to pic flags on Linux

[lrineau]

Describe the pull request

Because /usr/bin/libtool has that line of code:

pic_flag=" -fPIC -DPIC"

That macro definition PIC can trigger different assembler code, as for example in GMP assembler code.

*Note: I think the same bug applies to the other toolchains using -fPIC:

scripts/toolchains/android.cmake
scripts/toolchains/freebsd.cmake
scripts/toolchains/ios.cmake
scripts/toolchains/openbsd.cmake
scripts/toolchains/linux.cmake
scripts/toolchains/osx.cmake

but I can test only on Linux. Should I commit a similar change in all those files, and let the CI scripts and others test locally? In my opinion, I hardly see how adding -DPIC can harm.

• What does your PR fix?

  Fixes [MPIR:x64-linux] build failure (static linking) #13827.

• Which triplets are supported/not supported? Have you updated the CI baseline?

  all

• Does your PR follow the maintainer guide?

  yes I think so

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  not applicable

[Neumann-A]

Rebuild gmp with #25009 merged in. An retry the issue in #13827. Currently the linker flags are not correctly passed if i remember correctly.

According to docs. -fPIC defines __PIC__ so upstream should check against that and not a arbitrary define added by libtool.

[lrineau]

Rebuild gmp with #25009 merged in. An retry the issue in #13827. Currently the linker flags are not correctly passed if i remember correctly.

I have tried to merge #25009 in master but I still had the issue #13827. Only the define of -DPIC fixes it.

According to docs. -fPIC defines __PIC__ so upstream should check against that and not a arbitrary define added by libtool.

Do you mean that this PR will not be accepted? The upstream GMP project documents that --with-pic should be added to ./configure. But @BillyONeal said in #13827 (comment) that the enabling of PIC should be from the toolchain, and not from the GMP port file. That is why I have created this PR (#25158).

[JonLiu1993]

@lrineau, Thanks for your pr, looks ci test failed on x64-linux triplet
This is error log, please take a look:
llvm:
install-x64-linux-dbg-out.log
libmikmod:
install-x64-linux-dbg-out.log

[lrineau]

@lrineau, Thanks for your pr, looks ci test failed on x64-linux triplet
This is error log, please take a look:
llvm:
install-x64-linux-dbg-out.log
libmikmod:
install-x64-linux-dbg-out.log

For libmikmod, I do not understand the error, and how it might be related to PIC being a macro.

As for llvm, there is an understandable issue: PIC is used as a symbol name in the code:

llvm/include/llvm/MC/MCObjectFileInfo.h:237:52: note: in expansion of macro ‘PIC’
  237 |   void initMCObjectFileInfo(MCContext &MCCtx, bool PIC,
      |                                                    ^~~

That means PIC cannot be defined by the toolchain. I close this PR, and will try again to act on the gmp port itself.