Meson calls `path/to/clang++ --version` to guess which build toolchain the
user has picked to build the source code. For the Qualcomm LLVM toolchain,
the output have an unusual output as shown below:
```
clang version 8.0.12
Snapdragon LLVM ARM Compiler 8.0.12 (based on llvm.org 7.0+)
Target: arm-unknown-linux-gnueabi
Thread model: posix
Repository: (ssh://git-hexagon-aus.qualcomm.com:...)
InstalledDir: /pkg/qct/software/llvm/release/arm/8.0.12/bin
```
Another unusual pattern is the output of `path/to/ld.qcld --version`:
```
ARM Linker from Snapdragon LLVM ARM Compiler Version 8.0.12
ARM Linker based on LLVM version: 8.0
```
The Meson logic is modified accordingly so that Meson can correctly
determine toolchain as "LLVM aarch64 cross-compiler on GNU/Linux64 OS".
This is the expected output of
`meson --native-file native_file.ini --cross-file cross_file.ini build/aarch64-debug/`:
```
...
C++ compiler for the host machine: ... (clang 8.0.12 "clang version 8.0.12")
C++ linker for the host machine: ... ld.lld 8.0.12
...
```
Simmilar to gcc, the list of pre-processor defines can be fetched with
`-dM -E` option. The way cpu_family is determined on linux relies on
this list.
Fixes incorrect value of cpu_family on linux, when crosscompiling:
```
CC="clang -m32" meson ./build
```
Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
Co-authored-by: Dylan Baker <dylan@pnwbakers.com>
Clang supports the GCC -Og flag, but --optimization=g is not setting that. This is because Clang is referencing the clike_optimization_args, which does not define a flag for 'g'.
To address this, we'll mimic the GNU options instead of the C-like ones.
Fixes#6619
Now that the linkers are split out of the compilers this enum is
only used to know what platform we're compiling for. Which is
what the MachineInfo class is for
Dylan Baker