Mac OS, LLVM 3.7 and missing math.h header

Question

I need to use older version of LLVM on my Mac OS 10.12, namely 3.7 because it is required by ghc.

I have installed it via: brew install [email protected].

Now I am getting the <stdin>:1:10: fatal error: 'math.h' file not found error when I do even the simplest thing:

echo '#include <math.h>' | clang-3.7 -xc -v -

Real code that produces this error is my attempt to run ghc -fllvm on a simple helloworld.hs code which I want to get as LLVM bitcode.

I have done:

$ find /usr/local/Cellar/llvm\@3.7 | grep math
/usr/local/Cellar/[email protected]/3.7.1/lib/llvm-3.7/include/c++/v1/cmath
/usr/local/Cellar/[email protected]/3.7.1/lib/llvm-3.7/include/c++/v1/ctgmath
/usr/local/Cellar/[email protected]/3.7.1/lib/llvm-3.7/include/c++/v1/tgmath.h
/usr/local/Cellar/[email protected]/3.7.1/lib/llvm-3.7/lib/clang/3.7.1/include/tgmath.h

I am seeing that there is no any math.h headers.

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.0.2

What am I missing?

Answer 1

I have realized what was my mistake: I should have looked missing math.h in C headers, not C++ headers.

Adding either of the following to the C compiler flags in /usr/local/Cellar/ghc/8.0.2/lib/ghc-8.0.2/settings fixes the problem:

-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk

or

-idirafter /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/