Added 'Asan' build type.

`make asan` will link against ASan; the resulting
executable will do checks for memory access issues.

Thanks @JordanMilne for the suggestion.

CMakeLists.txt

@@ -1,5 +1,6 @@
 project(cmark)
 cmake_minimum_required(VERSION 2.8.9)
+include("FindAsan.cmake")
 
 if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
     message(FATAL_ERROR "Do not build in-source.\nPlease remove CMakeCache.txt and the CMakeFiles/ directory.\nThen: mkdir build ; cd build ; cmake .. ; make")

FindAsan.cmake

@@ -0,0 +1,74 @@
+#
+# The MIT License (MIT)
+#
+# Copyright (c) 2013 Matthew Arsenault
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+# This module tests if address sanitizer is supported by the compiler,
+# and creates a ASan build type (i.e. set CMAKE_BUILD_TYPE=ASan to use
+# it). This sets the following variables:
+#
+# CMAKE_C_FLAGS_ASAN - Flags to use for C with asan
+# CMAKE_CXX_FLAGS_ASAN  - Flags to use for C++ with asan
+# HAVE_ADDRESS_SANITIZER - True or false if the ASan build type is available
+
+include(CheckCCompilerFlag)
+
+# Set -Werror to catch "argument unused during compilation" warnings
+set(CMAKE_REQUIRED_FLAGS "-Werror -faddress-sanitizer") # Also needs to be a link flag for test to pass
+check_c_compiler_flag("-faddress-sanitizer" HAVE_FLAG_ADDRESS_SANITIZER)
+
+set(CMAKE_REQUIRED_FLAGS "-Werror -fsanitize=address") # Also needs to be a link flag for test to pass
+check_c_compiler_flag("-fsanitize=address" HAVE_FLAG_SANITIZE_ADDRESS)
+
+unset(CMAKE_REQUIRED_FLAGS)
+
+if(HAVE_FLAG_SANITIZE_ADDRESS)
+  # Clang 3.2+ use this version
+  set(ADDRESS_SANITIZER_FLAG "-fsanitize=address")
+elseif(HAVE_FLAG_ADDRESS_SANITIZER)
+  # Older deprecated flag for ASan
+  set(ADDRESS_SANITIZER_FLAG "-faddress-sanitizer")
+endif()
+
+if(NOT ADDRESS_SANITIZER_FLAG)
+  return()
+else(NOT ADDRESS_SANITIZER_FLAG)
+  set(HAVE_ADDRESS_SANITIZER FALSE)
+endif()
+
+set(HAVE_ADDRESS_SANITIZER TRUE)
+
+set(CMAKE_C_FLAGS_ASAN "-O1 -g ${ADDRESS_SANITIZER_FLAG} -fno-omit-frame-pointer -fno-optimize-sibling-calls"
+    CACHE STRING "Flags used by the C compiler during ASan builds."
+    FORCE)
+set(CMAKE_CXX_FLAGS_ASAN "-O1 -g ${ADDRESS_SANITIZER_FLAG} -fno-omit-frame-pointer -fno-optimize-sibling-calls"
+    CACHE STRING "Flags used by the C++ compiler during ASan builds."
+    FORCE)
+set(CMAKE_EXE_LINKER_FLAGS_ASAN "${ADDRESS_SANITIZER_FLAG}"
+    CACHE STRING "Flags used for linking binaries during ASan builds."
+    FORCE)
+set(CMAKE_SHARED_LINKER_FLAGS_ASAN "${ADDRESS_SANITIZER_FLAG}"
+    CACHE STRING "Flags used by the shared libraries linker during ASan builds."
+    FORCE)
+mark_as_advanced(CMAKE_C_FLAGS_ASAN
+                 CMAKE_CXX_FLAGS_ASAN
+                 CMAKE_EXE_LINKER_FLAGS_ASAN
+                 CMAKE_SHARED_LINKER_FLAGS_ASAN)

Makefile

@@ -19,7 +19,7 @@ VERSION?=$(SPECVERSION)
 RELEASE?=CommonMark-$(VERSION)
 INSTALL_PREFIX?=/usr/local
 
-.PHONY: all cmake_build spec leakcheck clean fuzztest dingus upload test update-site upload-site debug mingw archive bench astyle update-spec
+.PHONY: all cmake_build spec leakcheck clean fuzztest dingus upload test update-site upload-site debug asan mingw archive bench astyle update-spec
 
 all: cmake_build man/man3/cmark.3
 
@@ -47,6 +47,12 @@ debug:
 	cmake .. -DCMAKE_BUILD_TYPE=Debug; \
 	make
 
+asan:
+	mkdir -p $(BUILDDIR); \
+	cd $(BUILDDIR); \
+	cmake .. -DCMAKE_BUILD_TYPE=Asan; \
+	make
+
 prof:
 	mkdir -p $(BUILDDIR); \
 	cd $(BUILDDIR); \