[[native_binaries:preCompiledHeaders]]
== Precompiled Headers

Precompiled headers are a performance optimization that reduces the cost of compiling widely used headers multiple times. This feature _precompiles_ a header such that the compiled object file can be reused when compiling each source file rather than recompiling the header each time. This support is available for C, C+\+, Objective-C, and Objective-C++ builds.

#     rbe_linux: General RBE options used on all linux builds.
#     rbe_win_base:   General RBE options used on all Windows builds. Not to be used standalone.
#     rbe_win_clang:  Options specific to compiling using Clang.
#
#     rbe_linux_cpu:                  RBE options to build with only CPU support.
#     rbe_linux_cuda:                 RBE options to build with GPU support using clang.

//   GTEST_LINKED_AS_SHARED_LIBRARY
//                            - Define to 1 when compiling tests that use
//                              Google Test as a shared library (known as
//                              DLL on Windows).
//   GTEST_CREATE_SHARED_LIBRARY
//                            - Define to 1 when compiling Google Test itself
//                              as a shared library.

====

See link:{javadocPath}/org/gradle/api/tasks/testing/Test.html#useJUnitPlatform--[Test.useJUnitPlatform()] for more details.

[[compiling_and_executing_junit_jupiter_tests]]
=== Compiling and executing JUnit Jupiter tests

To enable JUnit Jupiter support in Gradle, all you need to do is add the following dependency:

.JUnit Jupiter dependencies
====

    print('WARNING: The NDK version in %s is %s, which is not '
          'supported by Bazel (officially supported versions: %s). Please use '
          'another version. Compiling Android targets may result in confusing '
          'errors.\n' %
          (android_ndk_home_path, ndk_version, _SUPPORTED_ANDROID_NDK_VERSIONS))
  write_action_env_to_bazelrc('ANDROID_NDK_VERSION', ndk_version)

[[sec:compilation_warnings]]
=== Compilation warnings

Gradle Kotlin DSL scripts are compiled by Gradle during the configuration phase of your build.
Deprecation warnings found by the Kotlin compiler are reported on the console when compiling the scripts.

[source,text]
----
> Configure project :
w: build.gradle.kts:4:5: 'getter for uploadTaskName: String!' is deprecated. Deprecated in Java
----

var tsanProlog = noTsanProlog

// noMsanProlog is a prologue defining an MSAN function in C.
// This is used when not compiling with -fsanitize=memory.
const noMsanProlog = `
#define _cgo_msan_write(addr, sz)
`

// yesMsanProlog is a prologue defining an MSAN function in C.
// This is used when compiling with -fsanitize=memory.
// See the comment above where _cgo_msan_write is called.
const yesMsanProlog = `

//
// This is a function instead of a variable because the exact toolenv depends
// on the GOOS and GOARCH, and (at least for now) those are modified in place
// to switch between the host and target configurations when cross-compiling.
func toolenv() []string {
	var env []string
	if !mustLinkExternal(goos, goarch, false) {
		// Unless the platform requires external linking,
		// we disable cgo to get static binaries for cmd/go and cmd/pprof,

	buildmode string // If non-empty, -buildmode flag

	env []string // Environment variables to add, as KEY=VAL. KEY= unsets a variable

	runOnHost bool // When cross-compiling, run this test on the host instead of guest

	// variant, if non-empty, is a name used to distinguish different
	// configurations of the same test package(s). If set and omitVariant is false,

)

# Sometimes Bazel reports darwin_x86_64 as "darwin" and sometimes as
# "darwin_x86_64". The former shows up when building on a Mac x86_64 host for a Mac x86_64 target.
# The latter shows up when cross-compiling for Mac x86_64 from a Mac ARM machine and in internal
# Google builds.
config_setting(
    name = "macos_x86_64_default",
    constraint_values = if_google(
        ["//third_party/bazel_platforms/os:macos"],