docs: state C++14 requirement

Fix: jupp0r#610

Author: gjasny

CMakeLists.txt

@@ -23,7 +23,7 @@ option(ENABLE_COMPRESSION "Enable gzip compression" ON)
 option(ENABLE_TESTING "Build tests" ON)
 option(USE_THIRDPARTY_LIBRARIES "Use 3rdParty submodules" ON)
 option(THIRDPARTY_CIVETWEB_WITH_SSL "Enable SSL support for embedded civetweb source code")
-option(OVERRIDE_CXX_STANDARD_FLAGS "Force building with -std=c++11 even if the CXXLFAGS are configured differently" ON)
+option(OVERRIDE_CXX_STANDARD_FLAGS "Force building with -std=c++14 even if the CXXLFAGS are configured differently" ON)
 option(GENERATE_PKGCONFIG "Generate and install pkg-config files" ${UNIX})
 option(RUN_IWYU "Run include-what-you-use" OFF)
 

README.md

@@ -92,7 +92,7 @@ int main() {
 
 ## Requirements
 
-Using `prometheus-cpp` requires a C++11 compliant compiler. It has been successfully tested with GNU GCC 7.4 on Ubuntu Bionic (18.04) and Visual Studio 2017 (but Visual Studio 2015 should work, too).
+Using `prometheus-cpp` requires a C++14 compliant compiler. It has been successfully tested with GNU GCC 7.4 on Ubuntu Bionic (18.04) and Visual Studio 2017.
 
 ## Building
 
@@ -247,20 +247,19 @@ guidelines](https://chris.beams.io/posts/git-commit/).
 
 You can check out this repo and build the library using
 ``` bash
-bazel build //... # build everything
-bazel build //core //pull # build just the libraries
+bazel build --cxxopt=-std=c++14 //...
 ```
 
 Run the unit tests using
 ```
-bazel test //...
+bazel test --cxxopt=-std=c++14 //...
 ```
 
 There is also an integration test that
 uses [telegraf](https://github.com/influxdata/telegraf) to scrape a
 sample server. With telegraf installed, it can be run using
 ```
-bazel test //pull/tests/integration:scrape-test
+bazel test --cxxopt=-std=c++14 //pull/tests/integration:scrape-test
 ```
 
 ## Benchmarks