CMake: support sanitizers on gcc builds, too.

This also fixes Travis Linux builds.

.travis/build-debian.sh

@@ -4,8 +4,10 @@ if echo $TRAVIS_TAG | grep ^v; then BUILD_TYPE=RelWithDebInfo; else BUILD_TYPE=D
 
 mkdir build
 cd build
-# We build without the GUI until Travis updates to an Ubuntu version with GTK 3.22.
-cmake .. -DCMAKE_C_COMPILER=clang-3.9 -DCMAKE_CXX_COMPILER=clang++-3.9 \
+# We build without the GUI until Travis updates to an Ubuntu version with GTK 3.16+.
+cmake .. \
+  -DCMAKE_C_COMPILER=gcc-5 \
+  -DCMAKE_CXX_COMPILER=g++-5 \
   -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
   -DENABLE_GUI=OFF \
   -DENABLE_SANITIZERS=ON

.travis/install-debian.sh

@@ -1,10 +1,8 @@
 #!/bin/sh -xe
 
-wget -O - http://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
 sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-sudo add-apt-repository -y 'deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-3.9 main'
 sudo apt-get update -qq
 sudo apt-get install -q -y \
   cmake cmake-data libc6-dev libpng12-dev zlib1g-dev libjson0-dev libfontconfig1-dev \
   libgtkmm-3.0-dev libpangomm-1.4-dev libcairo2-dev libgl1-mesa-dev libglu-dev \
-  libfreetype6-dev dpkg-dev libstdc++-5-dev clang-3.9 clang++-3.9 lcov
+  libfreetype6-dev dpkg-dev gcc-5 g++-5 lcov

CMakeLists.txt

@@ -80,15 +80,20 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
 endif()
 
 if(ENABLE_SANITIZERS)
-    if(NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-        message(FATAL_ERROR "Sanitizers are only available when using Clang/Clang++")
+    list(APPEND SANITIZERS address alignment bounds)
+    list(APPEND SANITIZERS shift signed-integer-overflow integer-divide-by-zero)
+    list(APPEND SANITIZERS null bool enum)
+    list(APPEND SANITIZERS return)
+    string(REPLACE ";" "," SANITIZERS "${SANITIZERS}")
+    set(SANITIZE_FLAGS "-O1 -fsanitize=${SANITIZERS} -fno-sanitize-recover=address,undefined")
+
+    if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+        set(SANITIZE_FLAGS "${SANITIZE_FLAGS} -fno-omit-frame-pointer -fno-optimize-sibling-calls")
+    elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
+        set(SANITIZE_FLAGS "${SANITIZE_FLAGS} -fuse-ld=gold")
+    else()
+        message(FATAL_ERROR "Sanitizers are only available when using GCC or Clang")
     endif()
-    set(SANITIZE_FLAGS  "-O1 -fno-omit-frame-pointer -fno-optimize-sibling-calls")
-    set(SANITIZE_FLAGS  "${SANITIZE_FLAGS} -fsanitize=address,integer")
-    set(SANITIZE_FLAGS  "${SANITIZE_FLAGS} -fno-sanitize-recover=integer")
-    # We assume IEEE floats, which means DIV/0 is defined; but ubsan doesn't do so by default.
-    set(SANITIZE_FLAGS  "${SANITIZE_FLAGS} -fno-sanitize=float-divide-by-zero")
-    set(SANITIZE_FLAGS  "${SANITIZE_FLAGS} -fno-sanitize=unsigned-integer-overflow")
 
     set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS} ${SANITIZE_FLAGS}")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${SANITIZE_FLAGS}")