From df60aeb2667e140a6c6ae93e9e1d8eb3d33d72ab Mon Sep 17 00:00:00 2001
From: Dominic Hamon <dominichamon@users.noreply.github.com>
Date: Fri, 23 Mar 2018 11:45:15 +0000
Subject: [PATCH] Rely on compiler intrinsics to identify regex engine. (#555)

Having the copts set on a per-target level can lead to ODR violations
in some cases. Avoid this by ensuring the regex engine is picked
through compiler intrinsics in the header directly.
---
 BUILD.bazel           |  3 ---
 bazel/BUILD           | 16 ----------------
 bazel/have_regex.bzl  |  7 -------
 src/internal_macros.h |  1 +
 src/re.h              | 24 ++++++++++++++++++------
 test/BUILD            |  4 +---
 6 files changed, 20 insertions(+), 35 deletions(-)
 delete mode 100644 bazel/BUILD
 delete mode 100644 bazel/have_regex.bzl

diff --git a/BUILD.bazel b/BUILD.bazel
index 883ccc44..35605ccb 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -1,7 +1,5 @@
 licenses(["notice"])
 
-load("//bazel:have_regex.bzl", "have_regex_copts")
-
 cc_library(
     name = "benchmark",
     srcs = glob([
@@ -9,7 +7,6 @@ cc_library(
         "src/*.h",
     ]),
     hdrs = ["include/benchmark/benchmark.h"],
-    copts = have_regex_copts(),
     strip_include_prefix = "include",
     visibility = ["//visibility:public"],
 )
diff --git a/bazel/BUILD b/bazel/BUILD
deleted file mode 100644
index dcbd4376..00000000
--- a/bazel/BUILD
+++ /dev/null
@@ -1,16 +0,0 @@
-package(default_visibility = ["//:__subpackages__"])
-
-config_setting(
-    name = "have_std_regex",
-    values = {"define": "google_benchmark.have_regex=std"},
-)
-
-config_setting(
-    name = "have_posix_regex",
-    values = {"define": "google_benchmark.have_regex=posix"},
-)
-
-config_setting(
-    name = "have_gnu_posix_regex",
-    values = {"define": "google_benchmark.have_regex=gnu_posix"},
-)
diff --git a/bazel/have_regex.bzl b/bazel/have_regex.bzl
deleted file mode 100644
index 6ea5ba01..00000000
--- a/bazel/have_regex.bzl
+++ /dev/null
@@ -1,7 +0,0 @@
-def have_regex_copts():
-  return select({
-      "//bazel:have_std_regex": ["-DHAVE_STD_REGEX"],
-      "//bazel:have_posix_regex": ["-DHAVE_POSIX_REGEX"],
-      "//bazel:have_gnu_posix_regex": ["-DHAVE_GNU_POSIX_REGEX"],
-      "//conditions:default": ["-DHAVE_STD_REGEX"],
-  })
diff --git a/src/internal_macros.h b/src/internal_macros.h
index f299722c..248ef262 100644
--- a/src/internal_macros.h
+++ b/src/internal_macros.h
@@ -39,6 +39,7 @@
 #elif defined(_WIN32)
   #define BENCHMARK_OS_WINDOWS 1
 #elif defined(__APPLE__)
+  #define BENCHMARK_OS_APPLE 1
   #include "TargetConditionals.h"
   #if defined(TARGET_OS_MAC)
     #define BENCHMARK_OS_MACOSX 1
diff --git a/src/re.h b/src/re.h
index 01e97365..924d2f0b 100644
--- a/src/re.h
+++ b/src/re.h
@@ -17,19 +17,31 @@
 
 #include "internal_macros.h"
 
+#if !defined(HAVE_STD_REGEX) && \
+    !defined(HAVE_GNU_POSIX_REGEX) && \
+    !defined(HAVE_POSIX_REGEX)
+  // No explicit regex selection; detect based on builtin hints.
+  #if defined(BENCHMARK_OS_LINUX) || defined(BENCHMARK_OS_APPLE)
+    #define HAVE_POSIX_REGEX 1
+  #elif __cplusplus >= 199711L
+    #define HAVE_STD_REGEX 1
+  #endif
+#endif
+
 // 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) && \
+#if defined(BENCHMARK_HAS_NO_EXCEPTIONS) && \
+    defined(BENCHMARK_HAVE_STD_REGEX) && \
     (defined(HAVE_GNU_POSIX_REGEX) || defined(HAVE_POSIX_REGEX))
-#undef HAVE_STD_REGEX
+  #undef HAVE_STD_REGEX
 #endif
 
 #if defined(HAVE_STD_REGEX)
-#include <regex>
+  #include <regex>
 #elif defined(HAVE_GNU_POSIX_REGEX)
-#include <gnuregex.h>
+  #include <gnuregex.h>
 #elif defined(HAVE_POSIX_REGEX)
-#include <regex.h>
+  #include <regex.h>
 #else
 #error No regular expression backend was found!
 #endif
@@ -64,7 +76,7 @@ class Regex {
 #elif defined(HAVE_POSIX_REGEX) || defined(HAVE_GNU_POSIX_REGEX)
   regex_t re_;
 #else
-#error No regular expression backend implementation available
+  #error No regular expression backend implementation available
 #endif
 };
 
diff --git a/test/BUILD b/test/BUILD
index 9e5d4936..c2682210 100644
--- a/test/BUILD
+++ b/test/BUILD
@@ -1,5 +1,3 @@
-load("//bazel:have_regex.bzl", "have_regex_copts")
-
 NEEDS_GTEST_MAIN = [
     "statistics_test.cc",
 ]
@@ -8,7 +6,7 @@ TEST_COPTS = [
     "-pedantic",
     "-pedantic-errors",
     "-std=c++11",
-] + have_regex_copts()
+]
 
 TEST_ARGS = ["--benchmark_min_time=0.01"]