From b016f218fbce4c01827a4bf613912b40f646e1df Mon Sep 17 00:00:00 2001
From: Antonio Ospite <antonio.ospite@collabora.com>
Date: Tue, 14 Jan 2025 12:47:52 +0100
Subject: [PATCH] ci/android: fix meson C++ cross-compiler argument detection

When cross-building for Android meson fails to find supported compiler
arguments for the  C++ cross-compiler, e.g.:

```
Compiler for C++ supports arguments -Wno-array-bounds: NO (cached)
Compiler for C++ supports arguments -Wno-overflow: NO
Compiler for C++ supports arguments -Wno-c++11-narrowing: NO (cached)
Compiler for C++ supports arguments -Wno-vla-cxx-extension: NO (cached)

```

This is due to an **unrelated** and more generic compilation failure
when testing for the supported arguments, e.g.:

```
Command line: `/tmp/android-ndk-r27c/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android34-clang++ -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables -static-libstdc++ /home/ao2/Collabora/GOO0042/mesa/_build/meson-private/tmpv6_hke9l/testfile.cpp -o /home/ao2/Collabora/GOO0042/mesa/_build/meson-private/tmpv6_hke9l/output.obj -c -Wno-error=c99-designator -Wno-error=unused-variable -Wno-error=unused-but-set-variable -Wno-error=self-assign -D_FILE_OFFSET_BITS=64 -O0 -fpermissive -Werror=implicit-function-declaration -Werror=unknown-warning-option -Werror=unused-command-line-argument -Werror=ignored-optimization-argument -Wvla-cxx-extension -Wno-vla-cxx-extension` -> 1
stderr:
clang++: error: argument unused during compilation: '-static-libstdc++' [-Werror,-Wunused-command-line-argument]
-----------
Compiler for C++ supports arguments -Wno-vla-cxx-extension: NO
```

The issue is caused by how the cross compiler is set up by
.gitlab-ci/container/create-android-cross-file.sh

Allow the cross compiler to still start even when the
`-Werror,-Wunused-command-line-argument` error occurs in order to be
able to actually detect other arguments:

```
Command line: `/tmp/android-ndk-r27c/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android34-clang++ -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables --start-no-unused-arguments -static-libstdc++ --end-no-unused-arguments /home/ao2/Collabora/GOO0042/mesa/_build/meson-private/tmpm6eolxed/testfile.cpp -o /home/ao2/Collabora/GOO0042/mesa/_build/meson-private/tmpm6eolxed/output.obj -c -Wno-error=c99-designator -Wno-error=unused-variable -Wno-error=unused-but-set-variable -Wno-error=self-assign -D_FILE_OFFSET_BITS=64 -O0 -fpermissive -Werror=implicit-function-declaration -Werror=unknown-warning-option -Werror=unused-command-line-argument -Werror=ignored-optimization-argument -Wvla-cxx-extension -Wno-vla-cxx-extension` -> 0
Compiler for C++ supports arguments -Wno-vla-cxx-extension: YES
```

This makes argument detection work again, e.g:

```
Compiler for C++ supports arguments -Wno-array-bounds: YES (cached)
Compiler for C++ supports arguments -Wno-overflow: YES
Compiler for C++ supports arguments -Wno-c++11-narrowing: YES (cached)
Compiler for C++ supports arguments -Wno-vla-cxx-extension: YES (cached)
```

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12441
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Valentine Burley <valentine.burley@collabora.com>
Reviewed-by: Rob Clark <robclark@freedesktop.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33013>
---
 .gitlab-ci/container/create-android-cross-file.sh | 2 +-
 docs/android.rst                                  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.gitlab-ci/container/create-android-cross-file.sh b/.gitlab-ci/container/create-android-cross-file.sh
index a29aafe1f65..d815a7e1cf5 100644
--- a/.gitlab-ci/container/create-android-cross-file.sh
+++ b/.gitlab-ci/container/create-android-cross-file.sh
@@ -18,7 +18,7 @@ cat > "$cross_file" <<EOF
 [binaries]
 ar = '$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-ar'
 c = ['ccache', '$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/${arch2}${sdk_version}-clang', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables']
-cpp = ['ccache', '$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/${arch2}${sdk_version}-clang++', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables', '-static-libstdc++']
+cpp = ['ccache', '$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/${arch2}${sdk_version}-clang++', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables', '--start-no-unused-arguments', '-static-libstdc++', '--end-no-unused-arguments']
 c_ld = 'lld'
 cpp_ld = 'lld'
 strip = '$ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-strip'
diff --git a/docs/android.rst b/docs/android.rst
index 692ce2ec17a..b46dddfaa52 100644
--- a/docs/android.rst
+++ b/docs/android.rst
@@ -27,7 +27,7 @@ Then, create your Meson cross file to use it, something like this
     [binaries]
     ar = 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ar'
     c = ['ccache', 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang']
-    cpp = ['ccache', 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang++', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables', '-static-libstdc++']
+    cpp = ['ccache', 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang++', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables', '--start-no-unused-arguments', '-static-libstdc++', '--end-no-unused-arguments']
     c_ld = 'lld'
     cpp_ld = 'lld'
     strip = 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-strip'