Inside a Formula, how to properly refer to "/usr/local/opt/llvm@11/bin/clang"?

[gwerbin]

I am working on packaging C2FFI and have successfully built it: rpav/c2ffi#100.

However, I am not sure how to specify the path /usr/local/opt/llvm@11 in the Formula. I can of course hard-code it, but that does not seems like a solution, because it makes this formula incompatible with Linux and other nonstandard installations.

This is what I have so far:

class C2ffi < Formula
  ...

  def install
    system(
      {LDFLAGS => "-L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib"},
      "cmake", "-S", ".", "-B", "build",
      *std_cmake_args,
      "-DBUILD_CONFIG=Release",
      "-DCMAKE_PREFIX_PATH=/usr/local/opt/llvm@11",
      -"DCMAKE_C_COMPILER=/usr/local/opt/llvm@11/bin/clang",
      "-DCMAKE_CXX_COMPILER=/usr/local/opt/llvm@11/bin/clang++",
    )
    system "cmake", "--build", "build"
    system "cmake", "--install", "build"
  end

  ...
end

The /usr/local/opt/llvm@11 part is what I want to avoid hard-coding.

[carlocab]

Try

Formula["llvm@11"].opt_bin/"clang"

You shouldn't need to set CMAKE_PREFIX_PATH, as brew sets this for you during the build based on the formula's dependencies.