[Buildroot] [PATCH 1/2] package/re2: new package

[Romain Naour]

Hello,

Le 07/09/2020 à 17:19, Thomas Petazzoni a écrit :
> Hello Michael,
> 
> Romain: there are some LLVM questions below.
> 
> On Mon, 07 Sep 2020 16:43:42 +0200
> "Michael Nosthoff" <buildroot at heine.tech> wrote:
> 
>> I did a check on what might happen when we add -DBUILD_SHARED_LIBS to package/pkg-cmake.mk for host packages.
>>
>> In Summary: a few packages change their output. Most stay stable. (see at the end for details)
> 
> First, thanks a lot for this extensive research.
> 
>> Builds that change their output from .a to .so: host-clang, host-grpc, host-flatcc, host-libabseil-cpp, host-lld, host-pugixml
>> builds that break: host-doxygen
>>
>> So for doxygen that is not good. They mix add_library calls which explicitly set STATIC and one that sets nothing. 
>> So this creates a .so but when it should be linked a .a is needed because the lib to be linked is static.
>> If we change the default doxygen would need an explicit -DBUILD_SHARED_LIBS=OFF Flag.
> 
> I think we could live with one host package explicitly disabling shared
> libraries.
> 
>> What I'm not sure about is the output of clang. Should this be built
>> as a shared lib? For llvm this is explicitly set to static in the
>> .mk. For clang this is not done for host builds. Is this maybe an
>> oversight?
> 
> On this, I don't know, but I've added Romain in Cc.

IIRC, we had some issues when BUILD_SHARED_LIBS was ON:
https://git.buildroot.net/buildroot/tree/package/llvm/llvm.mk#n70
https://git.buildroot.net/buildroot/tree/package/clang/clang.mk#n26

Indeed BUILD_SHARED_LIBS is missing for host-clang, I guess we shoud disable it.

Here is static libraries installed in host directory :
host]$ find -name "libclang*"
./lib/libclangCodeGen.a
./lib/libclangAnalysis.a
./lib/libclangStaticAnalyzerFrontend.a
./lib/libclangAST.a
./lib/libclangBasic.a
./lib/libclangRewrite.a
./lib/libclangHandleLLVM.a
./lib/libclangStaticAnalyzerCheckers.a
./lib/libclangSema.a
./lib/libclangIndex.a
./lib/libclangDriver.a
./lib/libclangFormat.a
./lib/libclangARCMigrate.a
./lib/libclangCrossTU.a
./lib/libclangASTMatchers.a
./lib/libclangFrontend.a
./lib/libclangParse.a
./lib/libclang.so
./lib/libclangHandleCXX.a
./lib/libclangStaticAnalyzerCore.a
./lib/libclangSerialization.a
./lib/libclangToolingRefactor.a
./lib/libclangTooling.a
./lib/libclangDynamicASTMatchers.a
./lib/libclangRewriteFrontend.a
./lib/libclangLex.a
./lib/libclangToolingASTDiff.a
./lib/libclangFrontendTool.a
./lib/libclangToolingCore.a
./lib/libclang.so.8
./lib/libclangEdit.a
./lib/libclangToolingInclusions.a


> 
>> So what do you think? Is this something we should go forward on or
>> should I just change the re2 package?
> 
> I think we should have the simple fix that tweaks just the re2 package,
> and then a more global fix in pkg-cmake.
> 
>> How is -DBUILD_SHARED_LIBS set and/or handled currently on the host packages?
>>
>> host-cdrkit always uses ADD_LIBRARY with STATIC flag
>> host-clang not set explicitly for host, so it might change from STATIC to SHARED here. Is this intentional or an oversight (compared to llvm)? [1]
>> host-doxygen adds most libs with STATIC but not all -> breaks on linking
>> host-fatcat Does not build libs
>> host-flatbuffers uses its own FLATBUFFERS_BUILD_SHAREDLIB, host .mk build sets it to OFF
>> host-flatcc has no preference, CMakeList.txt states explicitly that it honors BUILD_SHARED_LIBS
>> host-grpc honors the flag, .mk sets nothing
>> host-json-c Builds static and shared by default, setting flag doesn't change that
>> host-kodi-jsonschemabuilder only builds executable
>> host-kodi-texturepacker only builds executable
>> host-libabseil-cpp honors the flag, .mk sets nothing
>> host-libnetconf2 always uses ADD_LIBRARY with SHARED flag [2]
>> host-libyang Builds SHARED when ENABLE_STATIC is not set, which is the case [3]
>> host-libzip builds as shared as default
>> host-lld honors the flag, .mk sets nothing
>> host-llvm set to OFF by BR .mk file [4]
>> host-lzo .mk sets -DENABLE_SHARED=ON -DENABLE_STATIC=OFF
>> host-mariadb ignores DBUILD_SHARED_LIBS
>> host-mfgtools .mk defines its own build step (and builds shared lib)
>> host-ninja only build executable
>> host-pugixml honors -DBUILD_SHARED_LIBS
>> host-sysrepo sets shared as default [5]
>> host-thrift Sets to ON when not on windows [6]
>> host-waylandpp Defaults to OFF but doesn't build libs for host (-DBUILD_LIBRARIES=OFF) [7]
> 
> Again, thanks for this extensive research!

Ideed, Thanks!

Best regards,
Romain

> 
> Thomas
>