[llvm-dev] LLVM_CONFIG_PATH when building Clang from sources

[Jeffrey Walton via llvm-dev]

I'm trying to build LLVM, CFE and RT from sources on an old PowerMac
with OS X 10.5.

After download and unpack into LLVM_SOURCE_DIR (with
--strip-components=1), I configure with:

    cmake -DCMAKE_INSTALL_PREFIX="/opt/llvm" \
        -DLLVM_TARGETS_TO_BUILD="PowerPC" \
        -DLLVM_INCLUDE_TOOLS="ON" \
        -DLLVM_BUILD_TESTS="ON"
        "$LLVM_SOURCE_DIR"

It results in "llvm-config not found: specify LLVM_CONFIG_PATH". The
docs at https://llvm.org/docs/CMake.html don't appear to discuss
LLVM_CONFIG_PATH.

I'm building out-of-tree with these two variables:

    LLVM_SOURCE_DIR="$HOME/llvm_source"
    LLVM_BUILD_DIR="$HOME/llvm_build"

How should I fix the LLVM_CONFIG_PATH error?

Thanks in advance.

==============================

-- The C compiler identification is GNU 4.0.1
-- The CXX compiler identification is GNU 4.0.1
-- The ASM compiler identification is GNU
-- Found assembler: /Developer/usr/bin/cc
-- Checking whether C compiler has -isysroot
-- Checking whether C compiler has -isysroot - yes
-- Checking whether C compiler supports OSX deployment target flag
-- Checking whether C compiler supports OSX deployment target flag - yes
-- Check for working C compiler: /Developer/usr/bin/cc
-- Check for working C compiler: /Developer/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Checking whether CXX compiler has -isysroot
-- Checking whether CXX compiler has -isysroot - yes
-- Checking whether CXX compiler supports OSX deployment target flag
-- Checking whether CXX compiler supports OSX deployment target flag - yes
-- Check for working CXX compiler: /Developer/usr/bin/c++
-- Check for working CXX compiler: /Developer/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for unwind.h
-- Looking for unwind.h - found
CMake Error at cmake/Modules/CompilerRTUtils.cmake:213 (message):
  llvm-config not found: specify LLVM_CONFIG_PATH
Call Stack (most recent call first):
  CMakeLists.txt:66 (load_llvm_config)

-- Configuring incomplete, errors occurred!