Add suppport for manual specification of compile flags etc.

[fogti]

I haven't found documentation about this (I haven't looked at the code, yet). It would be nice to specify the additional CFLAGS and LDFLAGS either via zz.toml (this is kinda undocumented) and via environment variables (this is currently missing).

Use case: I have a "semi-broken" clang install, which requires additional linker flags/libraries to successfully link. Otherwise, it errors out with something like the following:

/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /usr/lib/llvm/9/bin/../../../../lib/clang/9.0.1/lib/linux/libclang_rt.asan-x86_64.a(sanitizer_unwind_linux_libcdep.cc.o): in function `__sanitizer::Unwind_GetIP(_Unwind_Context*)':
(.text+0x1): undefined reference to `_Unwind_GetIP'
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /usr/lib/llvm/9/bin/../../../../lib/clang/9.0.1/lib/linux/libclang_rt.asan-x86_64.a(sanitizer_unwind_linux_libcdep.cc.o): in function `__sanitizer::Unwind_Trace(_Unwind_Context*, void*)':
(.text+0x28): undefined reference to `_Unwind_GetIP'
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /usr/lib/llvm/9/bin/../../../../lib/clang/9.0.1/lib/linux/libclang_rt.asan-x86_64.a(sanitizer_unwind_linux_libcdep.cc.o): in function `__sanitizer::BufferedStackTrace::UnwindSlow(unsigned long, unsigned int)':
(.text+0xdf): undefined reference to `_Unwind_Backtrace'
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /usr/lib/llvm/9/bin/../../../../lib/clang/9.0.1/lib/linux/libclang_rt.asan-x86_64.a(sanitizer_unwind_linux_libcdep.cc.o): in function `__sanitizer::BufferedStackTrace::UnwindSlow(unsigned long, void*, unsigned int)':
(.text+0x2cd): undefined reference to `_Unwind_Backtrace'
clang-9: error: linker command failed with exit code 1 (use -v to see invocation)

(missing library would be probably -lunwind in this case).

[aep]

Hi.

zz.toml has both lflags and cflags.

I believe env variables are missing tho, will have to add those. They'd also fit your use case better because they're standard

[aep]

could you try if PR #23 suits your use case?

[fogti]

It fixes my use case.

(Now the hello example links successfully, but fails with a SIGSEGV at runtime...)

[aep]

great, please open a new bug for the segfault and try to attach as much info as possible.