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Commit 97b85314 authored by Jingwen Chen's avatar Jingwen Chen
Browse files

Add bp2build support for cpp_std. 

This converts cpp_std and gnu_extensions into a -std copt, if cpp_std is
specified or gnu_extensions is false if cpp_std is not specified.

I chose to go with this copts approach because the tradeoff is a much
simpler setting than adding a new attr(s) everywhere that uses features
to set the flag.

This approach limits the number of user-configurable knobs (since users
would then be able to set std in _both_ copts and the new attr). But it
does rely on the user copt overriding the toolchain's default gnu++17
version, which can mean a `-std` flag showing up twice in the action.

Fixes: b/202462232
Test: b build //system/libziparchive:libziparchive
Change-Id: I81dad029059461739b91f318d662e089edb46b84
parent 800112b9

bp2build/cc_library_conversion_test.go

+84 −0
Original line number Diff line number Diff line
@@ -1677,4 +1677,88 @@ cc_library { 
        "//conditions:default": [],

    }),

)`}})



}



func TestCcLibraryCppStdWithGnuExtensions_ConvertstoCopt(t *testing.T) {

	type testCase struct {

		cpp_std        string

		gnu_extensions string

		bazel_cpp_std  string

	}



	testCases := []testCase{

		// Existing usages of cpp_std in AOSP are:

		// experimental, c++11, c++17, c++2a, c++98, gnu++11, gnu++17

		//

		// not set, only emit if gnu_extensions is disabled. the default (gnu+17

		// is set in the toolchain.)

		{cpp_std: "", gnu_extensions: "", bazel_cpp_std: ""},

		{cpp_std: "", gnu_extensions: "false", bazel_cpp_std: "c++17"},

		{cpp_std: "", gnu_extensions: "true", bazel_cpp_std: ""},

		// experimental defaults to gnu++2a

		{cpp_std: "experimental", gnu_extensions: "", bazel_cpp_std: "gnu++2a"},

		{cpp_std: "experimental", gnu_extensions: "false", bazel_cpp_std: "c++2a"},

		{cpp_std: "experimental", gnu_extensions: "true", bazel_cpp_std: "gnu++2a"},

		// Explicitly setting a c++ std does not use replace gnu++ std even if

		// gnu_extensions is true.

		// "c++11",

		{cpp_std: "c++11", gnu_extensions: "", bazel_cpp_std: "c++11"},

		{cpp_std: "c++11", gnu_extensions: "false", bazel_cpp_std: "c++11"},

		{cpp_std: "c++11", gnu_extensions: "true", bazel_cpp_std: "c++11"},

		// "c++17",

		{cpp_std: "c++17", gnu_extensions: "", bazel_cpp_std: "c++17"},

		{cpp_std: "c++17", gnu_extensions: "false", bazel_cpp_std: "c++17"},

		{cpp_std: "c++17", gnu_extensions: "true", bazel_cpp_std: "c++17"},

		// "c++2a",

		{cpp_std: "c++2a", gnu_extensions: "", bazel_cpp_std: "c++2a"},

		{cpp_std: "c++2a", gnu_extensions: "false", bazel_cpp_std: "c++2a"},

		{cpp_std: "c++2a", gnu_extensions: "true", bazel_cpp_std: "c++2a"},

		// "c++98",

		{cpp_std: "c++98", gnu_extensions: "", bazel_cpp_std: "c++98"},

		{cpp_std: "c++98", gnu_extensions: "false", bazel_cpp_std: "c++98"},

		{cpp_std: "c++98", gnu_extensions: "true", bazel_cpp_std: "c++98"},

		// gnu++ is replaced with c++ if gnu_extensions is explicitly false.

		// "gnu++11",

		{cpp_std: "gnu++11", gnu_extensions: "", bazel_cpp_std: "gnu++11"},

		{cpp_std: "gnu++11", gnu_extensions: "false", bazel_cpp_std: "c++11"},

		{cpp_std: "gnu++11", gnu_extensions: "true", bazel_cpp_std: "gnu++11"},

		// "gnu++17",

		{cpp_std: "gnu++17", gnu_extensions: "", bazel_cpp_std: "gnu++17"},

		{cpp_std: "gnu++17", gnu_extensions: "false", bazel_cpp_std: "c++17"},

		{cpp_std: "gnu++17", gnu_extensions: "true", bazel_cpp_std: "gnu++17"},

	}

	for _, tc := range testCases {

		cppStdAttr := ""

		if tc.cpp_std != "" {

			cppStdAttr = fmt.Sprintf("    cpp_std: \"%s\",", tc.cpp_std)

		}

		gnuExtensionsAttr := ""

		if tc.gnu_extensions != "" {

			gnuExtensionsAttr = fmt.Sprintf("    gnu_extensions: %s,", tc.gnu_extensions)

		}

		bazelCppStdAttr := ""

		if tc.bazel_cpp_std != "" {

			bazelCppStdAttr = fmt.Sprintf("\n    copts = [\"-std=%s\"],", tc.bazel_cpp_std)

		}



		runCcLibraryTestCase(t, bp2buildTestCase{

			description: fmt.Sprintf(

				"cc_library with cpp_std: %s and gnu_extensions: %s", tc.cpp_std, tc.gnu_extensions),

			moduleTypeUnderTest:                "cc_library",

			moduleTypeUnderTestFactory:         cc.LibraryFactory,

			moduleTypeUnderTestBp2BuildMutator: cc.CcLibraryBp2Build,

			blueprint: soongCcLibraryPreamble + fmt.Sprintf(`

cc_library {

	name: "a",

%s // cpp_std: *string

%s // gnu_extensions: *bool

	include_build_directory: false,

}

`, cppStdAttr, gnuExtensionsAttr),

			expectedBazelTargets: []string{fmt.Sprintf(`cc_library(

    name = "a",%s

)`, bazelCppStdAttr)},

		})

	}

}

cc/bp2build.go

+18 −1
Original line number Diff line number Diff line
@@ -277,7 +277,24 @@ func bp2BuildParseCompilerProps(ctx android.TopDownMutatorContext, module *Modul 
					srcs.SetSelectValue(axis, config, srcsList)

				}



				archVariantCopts := parseCommandLineFlags(baseCompilerProps.Cflags)

				var archVariantCopts []string

				if axis == bazel.NoConfigAxis {

					// If cpp_std is not specified, don't generate it in the

					// BUILD file. For readability purposes, cpp_std and gnu_extensions are

					// combined into a single -std=<version> copt, except in the

					// default case where cpp_std is nil and gnu_extensions is true or unspecified,

					// then the toolchain's default "gnu++17" will be used.

					if baseCompilerProps.Cpp_std != nil {

						// TODO(b/202491296): Handle C_std.

						// These transformations are shared with compiler.go.

						cppStdVal := parseCppStd(baseCompilerProps.Cpp_std)

						_, cppStdVal = maybeReplaceGnuToC(baseCompilerProps.Gnu_extensions, "", cppStdVal)

						archVariantCopts = append(archVariantCopts, "-std="+cppStdVal)

					} else if baseCompilerProps.Gnu_extensions != nil && !*baseCompilerProps.Gnu_extensions {

						archVariantCopts = append(archVariantCopts, "-std=c++17")

					}

				}

				archVariantCopts = append(archVariantCopts, parseCommandLineFlags(baseCompilerProps.Cflags)...)

				archVariantAsflags := parseCommandLineFlags(baseCompilerProps.Asflags)



				localIncludeDirs := baseCompilerProps.Local_include_dirs

cc/compiler.go

+21 −11
Original line number Diff line number Diff line
@@ -305,6 +305,25 @@ func addToModuleList(ctx ModuleContext, key android.OnceKey, module string) { 
	getNamedMapForConfig(ctx.Config(), key).Store(module, true)

}



func maybeReplaceGnuToC(gnuExtensions *bool, cStd string, cppStd string) (string, string) {

	if gnuExtensions != nil && *gnuExtensions == false {

		cStd = gnuToCReplacer.Replace(cStd)

		cppStd = gnuToCReplacer.Replace(cppStd)

	}

	return cStd, cppStd

}



func parseCppStd(cppStdPtr *string) string {

	cppStd := String(cppStdPtr)

	switch cppStd {

	case "":

		cppStd = config.CppStdVersion

	case "experimental":

		cppStd = config.ExperimentalCppStdVersion

	}

	return cppStd

}



// Create a Flags struct that collects the compile flags from global values,

// per-target values, module type values, and per-module Blueprints properties

func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps PathDeps) Flags {
@@ -484,18 +503,9 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps 
		cStd = String(compiler.Properties.C_std)

	}



	cppStd := String(compiler.Properties.Cpp_std)

	switch String(compiler.Properties.Cpp_std) {

	case "":

		cppStd = config.CppStdVersion

	case "experimental":

		cppStd = config.ExperimentalCppStdVersion

	}

	cppStd := parseCppStd(compiler.Properties.Cpp_std)



	if compiler.Properties.Gnu_extensions != nil && *compiler.Properties.Gnu_extensions == false {

		cStd = gnuToCReplacer.Replace(cStd)

		cppStd = gnuToCReplacer.Replace(cppStd)

	}

	cStd, cppStd = maybeReplaceGnuToC(compiler.Properties.Gnu_extensions, cStd, cppStd)



	flags.Local.ConlyFlags = append([]string{"-std=" + cStd}, flags.Local.ConlyFlags...)

	flags.Local.CppFlags = append([]string{"-std=" + cppStd}, flags.Local.CppFlags...)