impl(generator): update emitted build files for c++17 (#16209)

Author: scotthart

generator/internal/scaffold_generator.cc

@@ -1022,6 +1022,9 @@ void GenerateQuickstartCMake(
 cmake_minimum_required(VERSION 3.22...3.31)
 project(google-cloud-cpp-$library$-quickstart CXX)
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 find_package(google_cloud_cpp_$library$ REQUIRED)
 
 # MSVC requires some additional code to select the correct runtime library
@@ -1062,7 +1065,7 @@ void GenerateQuickstartMakefile(
 # The CXX, CXXFLAGS and CXXLD variables are hard-coded. These values work for
 # our tests, but applications would typically make them configurable parameters.
 CXX=g++
-CXXFLAGS=
+CXXFLAGS=-std=c++17
 CXXLD=$$(CXX)
 BIN=.
 
@@ -1147,14 +1150,13 @@ void GenerateQuickstartBazelrc(
 # Use host-OS-specific config lines from bazelrc files.
 build --enable_platform_specific_config=true
 
-# The project requires C++ >= 14. By default Bazel adds `-std=c++0x` which
-# disables C++14 features, even if the compilers defaults to C++ >= 14
-build:linux --cxxopt=-std=c++14
-build:macos --cxxopt=-std=c++14
-# Protobuf and gRPC require (or soon will require) C++14 to compile the "host"
+# The project requires C++ >= 17.
+build:linux --cxxopt=-std=c++17
+build:macos --cxxopt=-std=c++17
+# Protobuf and gRPC require (or soon will require) C++17 to compile the "host"
 # targets, such as protoc and the grpc plugin.
-build:linux --host_cxxopt=-std=c++14
-build:macos --host_cxxopt=-std=c++14
+build:linux --host_cxxopt=-std=c++17
+build:macos --host_cxxopt=-std=c++17
 
 # Do not create the convenience links. They are inconvenient when the build
 # runs inside a docker image or if one builds a quickstart and then builds

generator/internal/scaffold_generator_test.cc

@@ -411,6 +411,7 @@ TEST_F(ScaffoldGenerator, QuickstartCMake) {
   EXPECT_THAT(actual, HasSubstr("2034"));
   EXPECT_THAT(actual, Not(HasSubstr("$copyright_year$")));
   EXPECT_THAT(actual, Not(HasSubstr("$library_prefix$")));
+  EXPECT_THAT(actual, HasSubstr("CMAKE_CXX_STANDARD 17"));
 }
 
 TEST_F(ScaffoldGenerator, QuickstartMakefile) {
@@ -421,6 +422,7 @@ TEST_F(ScaffoldGenerator, QuickstartMakefile) {
   EXPECT_THAT(actual, HasSubstr("2034"));
   EXPECT_THAT(actual, Not(HasSubstr("$copyright_year$")));
   EXPECT_THAT(actual, HasSubstr("\t$(CXXLD) "));
+  EXPECT_THAT(actual, HasSubstr("CXXFLAGS=-std=c++17"));
 }
 
 TEST_F(ScaffoldGenerator, QuickstartWorkspace) {
@@ -461,6 +463,8 @@ TEST_F(ScaffoldGenerator, QuickstartBazelrc) {
   auto const actual = std::move(os).str();
   EXPECT_THAT(actual, HasSubstr("2034"));
   EXPECT_THAT(actual, Not(HasSubstr("$copyright_year$")));
+  EXPECT_THAT(actual, HasSubstr("c++17"));
+  EXPECT_THAT(actual, Not(HasSubstr("c++14")));
 }
 
 }  // namespace

google/cloud/accessapproval/quickstart/.bazelrc

@@ -15,12 +15,11 @@
 # Use host-OS-specific config lines from bazelrc files.
 build --enable_platform_specific_config=true
 
-
-
+# The project requires C++ >= 17.
 build:linux --cxxopt=-std=c++17
 build:macos --cxxopt=-std=c++17
-
-
+# Protobuf and gRPC require (or soon will require) C++17 to compile the "host"
+# targets, such as protoc and the grpc plugin.
 build:linux --host_cxxopt=-std=c++17
 build:macos --host_cxxopt=-std=c++17
 

google/cloud/accessapproval/quickstart/CMakeLists.txt

@@ -18,6 +18,9 @@
 cmake_minimum_required(VERSION 3.22...3.31)
 project(google-cloud-cpp-accessapproval-quickstart CXX)
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 find_package(google_cloud_cpp_accessapproval REQUIRED)
 
 # MSVC requires some additional code to select the correct runtime library

google/cloud/accessapproval/quickstart/Makefile

@@ -18,7 +18,7 @@
 # The CXX, CXXFLAGS and CXXLD variables are hard-coded. These values work for
 # our tests, but applications would typically make them configurable parameters.
 CXX=g++
-CXXFLAGS=
+CXXFLAGS=-std=c++17
 CXXLD=$(CXX)
 BIN=.
 

google/cloud/accesscontextmanager/quickstart/.bazelrc

@@ -15,12 +15,11 @@
 # Use host-OS-specific config lines from bazelrc files.
 build --enable_platform_specific_config=true
 
-
-
+# The project requires C++ >= 17.
 build:linux --cxxopt=-std=c++17
 build:macos --cxxopt=-std=c++17
-
-
+# Protobuf and gRPC require (or soon will require) C++17 to compile the "host"
+# targets, such as protoc and the grpc plugin.
 build:linux --host_cxxopt=-std=c++17
 build:macos --host_cxxopt=-std=c++17
 

google/cloud/accesscontextmanager/quickstart/CMakeLists.txt

@@ -18,6 +18,9 @@
 cmake_minimum_required(VERSION 3.22...3.31)
 project(google-cloud-cpp-accesscontextmanager-quickstart CXX)
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 find_package(google_cloud_cpp_accesscontextmanager REQUIRED)
 
 # MSVC requires some additional code to select the correct runtime library

google/cloud/accesscontextmanager/quickstart/Makefile

@@ -18,7 +18,7 @@
 # The CXX, CXXFLAGS and CXXLD variables are hard-coded. These values work for
 # our tests, but applications would typically make them configurable parameters.
 CXX=g++
-CXXFLAGS=
+CXXFLAGS=-std=c++17
 CXXLD=$(CXX)
 BIN=.
 

google/cloud/advisorynotifications/quickstart/.bazelrc

@@ -15,12 +15,11 @@
 # Use host-OS-specific config lines from bazelrc files.
 build --enable_platform_specific_config=true
 
-
-
+# The project requires C++ >= 17.
 build:linux --cxxopt=-std=c++17
 build:macos --cxxopt=-std=c++17
-
-
+# Protobuf and gRPC require (or soon will require) C++17 to compile the "host"
+# targets, such as protoc and the grpc plugin.
 build:linux --host_cxxopt=-std=c++17
 build:macos --host_cxxopt=-std=c++17
 

google/cloud/advisorynotifications/quickstart/CMakeLists.txt

@@ -18,6 +18,9 @@
 cmake_minimum_required(VERSION 3.22...3.31)
 project(google-cloud-cpp-advisorynotifications-quickstart CXX)
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 find_package(google_cloud_cpp_advisorynotifications REQUIRED)
 
 # MSVC requires some additional code to select the correct runtime library