update standard to C++17 per C++ build support (#1875)

* update standard to C++17 per C++ build support

* disable deadcode checks from clang-tidy

* fix redundant definition of constexpr

.github/workflows/clang-tidy.yml

@@ -35,4 +35,4 @@ jobs:
     - name: run
       shell: bash
       working-directory: ${{ runner.workspace }}/_build
-      run: run-clang-tidy
+      run: run-clang-tidy -checks=*,-clang-analyzer-deadcode*

BUILD.bazel

@@ -3,7 +3,7 @@ licenses(["notice"])
 COPTS = [
     "-pedantic",
     "-pedantic-errors",
-    "-std=c++14",
+    "-std=c++17",
     "-Wall",
     "-Wconversion",
     "-Wextra",

CMakeLists.txt

@@ -138,7 +138,7 @@ if (BENCHMARK_BUILD_32_BITS)
   add_required_cxx_compiler_flag(-m32)
 endif()
 
-set(BENCHMARK_CXX_STANDARD 14)
+set(BENCHMARK_CXX_STANDARD 17)
 
 set(CMAKE_CXX_STANDARD ${BENCHMARK_CXX_STANDARD})
 set(CMAKE_CXX_STANDARD_REQUIRED YES)

src/perf_counters.cc

@@ -26,8 +26,6 @@
 namespace benchmark {
 namespace internal {
 
-constexpr size_t PerfCounterValues::kMaxCounters;
-
 #if defined HAVE_LIBPFM
 
 size_t PerfCounterValues::Read(const std::vector<int>& leaders) {

test/BUILD

@@ -10,7 +10,7 @@ platform(
 TEST_COPTS = [
     "-pedantic",
     "-pedantic-errors",
-    "-std=c++14",
+    "-std=c++17",
     "-Wall",
     "-Wconversion",
     "-Wextra",