Add support for building w/o exceptions (google#317)

CMakeLists.txt

@@ -11,6 +11,7 @@ foreach(p
 endforeach()
 
 option(BENCHMARK_ENABLE_TESTING "Enable testing of the benchmark library." ON)
+option(BENCHMARK_ENABLE_EXCEPTIONS "Enable the use of exceptions in the benchmark library." ON)
 option(BENCHMARK_ENABLE_LTO "Enable link time optimisation of the benchmark library." OFF)
 option(BENCHMARK_USE_LIBCXX "Build and test using libc++ as the standard library." OFF)
 # Make sure we can import out CMake functions
@@ -39,6 +40,10 @@ if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 
+  if (NOT BENCHMARK_ENABLE_EXCEPTIONS)
+    add_cxx_compiler_flag(-EHs-)
+    add_cxx_compiler_flag(-EHa-)
+  endif()
   # Link time optimisation
   if (BENCHMARK_ENABLE_LTO)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /GL")
@@ -80,6 +85,9 @@ else()
   add_cxx_compiler_flag(-Wshorten-64-to-32)
   add_cxx_compiler_flag(-Wfloat-equal)
   add_cxx_compiler_flag(-fstrict-aliasing)
+  if (NOT BENCHMARK_ENABLE_EXCEPTIONS)
+    add_cxx_compiler_flag(-fno-exceptions)
+  endif()
   if (NOT BENCHMARK_USE_LIBCXX)
     add_cxx_compiler_flag(-Wzero-as-null-pointer-constant)
   endif()
@@ -162,7 +170,10 @@ cxx_feature_check(POSIX_REGEX)
 if(NOT HAVE_STD_REGEX AND NOT HAVE_GNU_POSIX_REGEX AND NOT HAVE_POSIX_REGEX)
   message(FATAL_ERROR "Failed to determine the source files for the regular expression backend")
 endif()
-
+if (NOT BENCHMARK_ENABLE_EXCEPTIONS AND HAVE_STD_REGEX
+        AND NOT HAVE_GNU_POSIX_REGEX AND NOT HAVE_POSIX_REGEX)
+  message(WARNING "Using std::regex with exceptions disabled is not fully supported")
+endif()
 cxx_feature_check(STEADY_CLOCK)
 # Ensure we have pthreads
 find_package(Threads REQUIRED)

src/internal_macros.h

@@ -39,4 +39,9 @@
 #define BENCHMARK_OS_LINUX 1
 #endif
 
+#if !__has_feature(cxx_exceptions) && !defined(__cpp_exceptions) \
+     && !defined(__EXCEPTIONS)
+#define BENCHMARK_HAS_NO_EXCEPTIONS
+#endif
+
 #endif  // BENCHMARK_INTERNAL_MACROS_H_

src/re.h

@@ -15,6 +15,15 @@
 #ifndef BENCHMARK_RE_H_
 #define BENCHMARK_RE_H_
 
+#include "internal_macros.h"
+
+// Prefer C regex libraries when compiling w/o exceptions so that we can
+// correctly report errors.
+#if defined(BENCHMARK_HAS_NO_EXCEPTIONS) && defined(HAVE_STD_REGEX) && \
+    (defined(HAVE_GNU_POSIX_REGEX) || defined(HAVE_POSIX_REGEX))
+#undef HAVE_STD_REGEX
+#endif
+
 #if defined(HAVE_STD_REGEX)
 #include <regex>
 #elif defined(HAVE_GNU_POSIX_REGEX)
@@ -62,15 +71,20 @@ class Regex {
 #if defined(HAVE_STD_REGEX)
 
 inline bool Regex::Init(const std::string& spec, std::string* error) {
+#ifdef BENCHMARK_HAS_NO_EXCEPTIONS
+  ((void)error); // suppress unused warning
+#else
   try {
+#endif
     re_ = std::regex(spec, std::regex_constants::extended);
-
     init_ = true;
+#ifndef BENCHMARK_HAS_NO_EXCEPTIONS
   } catch (const std::regex_error& e) {
     if (error) {
       *error = e.what();
     }
   }
+#endif
   return init_;
 }