From 6e07d6dd2d11c7c779640f7cdb9c234875454e88 Mon Sep 17 00:00:00 2001
From: Dan Liew <daniel.liew@imperial.ac.uk>
Date: Sat, 29 Apr 2017 17:45:02 +0100
Subject: [PATCH] [CMake] Override CMake's default flags for GCC/Clang as we
 were doing before 4cc2b292c0cc8759da7a525e63dbfefdb06d6a01.

It's useful to be able to control the defaults and CMake's internal
logic for GCC/Clang is simple enough that doing this makes sense.

It would be nice to do the same for MSVC but CMake's internal
logic is more complicated so for now it's better that we just use
CMake's default.
---
 CMakeLists.txt                                     |  1 +
 .../cmake/cmake/cxx_compiler_flags_overrides.cmake | 14 ++++++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 contrib/cmake/cmake/cxx_compiler_flags_overrides.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index aa347ae66..19c56a413 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,6 +24,7 @@ if (NOT (EXISTS "${CMAKE_SOURCE_DIR}/src/CMakeLists.txt"))
           "``python contrib/cmake/bootstrap.py create``")
 endif()
 
+set(CMAKE_USER_MAKE_RULES_OVERRIDE_CXX "${CMAKE_CURRENT_SOURCE_DIR}/cmake/cxx_compiler_flags_overrides.cmake")
 project(Z3 CXX)
 
 ################################################################################
diff --git a/contrib/cmake/cmake/cxx_compiler_flags_overrides.cmake b/contrib/cmake/cmake/cxx_compiler_flags_overrides.cmake
new file mode 100644
index 000000000..59966f424
--- /dev/null
+++ b/contrib/cmake/cmake/cxx_compiler_flags_overrides.cmake
@@ -0,0 +1,14 @@
+# This file overrides the default compiler flags for CMake's built-in
+# configurations (CMAKE_BUILD_TYPE). Most compiler flags should not be set here.
+# The main purpose is to have very fine grained control of the compiler flags.
+
+# We only override the defaults for Clang and GCC right now.
+# CMake's MSVC logic is complicated so for now it's better to just inherit CMake's defaults.
+if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR ("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"))
+  # Taken from Modules/Compiler/GNU.cmake
+  set(CMAKE_CXX_FLAGS_INIT "")
+  set(CMAKE_CXX_FLAGS_DEBUG_INIT "-g -O0")
+  set(CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG")
+  set(CMAKE_CXX_FLAGS_RELEASE_INIT "-O3 -DNDEBUG")
+  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -DNDEBUG")
+endif()