Convert cpp_std to be an attribute instead of a copt.

This attribute is then converted into a feature in cc_library_static.

Fixes: 202518741
Test: CI
Change-Id: I070b56a1e96680ffad0466d085caaab2e9308ebc
diff --git a/cc/bp2build.go b/cc/bp2build.go
index 0b2c133..df938d2 100644
--- a/cc/bp2build.go
+++ b/cc/bp2build.go
@@ -226,7 +226,10 @@
 	srcs     bazel.LabelListAttribute
 
 	rtti bazel.BoolAttribute
-	stl  *string
+
+	// Not affected by arch variants
+	stl    *string
+	cppStd *string
 
 	localIncludes    bazel.StringListAttribute
 	absoluteIncludes bazel.StringListAttribute
@@ -242,6 +245,8 @@
 	var rtti bazel.BoolAttribute
 	var localIncludes bazel.StringListAttribute
 	var absoluteIncludes bazel.StringListAttribute
+	var stl *string = nil
+	var cppStd *string = nil
 
 	parseCommandLineFlags := func(soongFlags []string) []string {
 		var result []string
@@ -277,7 +282,6 @@
 					srcs.SetSelectValue(axis, config, srcsList)
 				}
 
-				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
@@ -289,11 +293,14 @@
 						// These transformations are shared with compiler.go.
 						cppStdVal := parseCppStd(baseCompilerProps.Cpp_std)
 						_, cppStdVal = maybeReplaceGnuToC(baseCompilerProps.Gnu_extensions, "", cppStdVal)
-						archVariantCopts = append(archVariantCopts, "-std="+cppStdVal)
+						cppStd = &cppStdVal
 					} else if baseCompilerProps.Gnu_extensions != nil && !*baseCompilerProps.Gnu_extensions {
-						archVariantCopts = append(archVariantCopts, "-std=c++17")
+						cppStdVal := "c++17"
+						cppStd = &cppStdVal
 					}
 				}
+
+				var archVariantCopts []string
 				archVariantCopts = append(archVariantCopts, parseCommandLineFlags(baseCompilerProps.Cflags)...)
 				archVariantAsflags := parseCommandLineFlags(baseCompilerProps.Asflags)
 
@@ -339,7 +346,6 @@
 
 	srcs, cSrcs, asSrcs := groupSrcsByExtension(ctx, srcs)
 
-	var stl *string = nil
 	stlPropsByArch := module.GetArchVariantProperties(ctx, &StlProperties{})
 	for _, configToProps := range stlPropsByArch {
 		for _, props := range configToProps {
@@ -367,6 +373,7 @@
 		cppFlags:         cppFlags,
 		rtti:             rtti,
 		stl:              stl,
+		cppStd:           cppStd,
 		localIncludes:    localIncludes,
 		absoluteIncludes: absoluteIncludes,
 	}
diff --git a/cc/library.go b/cc/library.go
index 0cffd56..00e215b 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -248,7 +248,9 @@
 	Linkopts               bazel.StringListAttribute
 	Use_libcrt             bazel.BoolAttribute
 	Rtti                   bazel.BoolAttribute
-	Stl                    *string
+
+	Stl     *string
+	Cpp_std *string
 
 	// This is shared only.
 	Version_script bazel.LabelAttribute
@@ -328,6 +330,7 @@
 		Use_libcrt:                  linkerAttrs.useLibcrt,
 		Rtti:                        compilerAttrs.rtti,
 		Stl:                         compilerAttrs.stl,
+		Cpp_std:                     compilerAttrs.cppStd,
 
 		Version_script: linkerAttrs.versionScript,
 
@@ -2403,6 +2406,7 @@
 			Use_libcrt:             linkerAttrs.useLibcrt,
 			Rtti:                   compilerAttrs.rtti,
 			Stl:                    compilerAttrs.stl,
+			Cpp_std:                compilerAttrs.cppStd,
 			Export_includes:        exportedIncludes.Includes,
 			Export_system_includes: exportedIncludes.SystemIncludes,
 			Local_includes:         compilerAttrs.localIncludes,
@@ -2427,6 +2431,7 @@
 			Use_libcrt: linkerAttrs.useLibcrt,
 			Rtti:       compilerAttrs.rtti,
 			Stl:        compilerAttrs.stl,
+			Cpp_std:    compilerAttrs.cppStd,
 
 			Export_includes:        exportedIncludes.Includes,
 			Export_system_includes: exportedIncludes.SystemIncludes,
@@ -2462,6 +2467,7 @@
 	Use_libcrt bazel.BoolAttribute
 	Rtti       bazel.BoolAttribute
 	Stl        *string
+	Cpp_std    *string
 
 	Export_includes        bazel.StringListAttribute
 	Export_system_includes bazel.StringListAttribute
@@ -2489,6 +2495,7 @@
 	Use_libcrt bazel.BoolAttribute
 	Rtti       bazel.BoolAttribute
 	Stl        *string
+	Cpp_std    *string
 
 	Export_includes        bazel.StringListAttribute
 	Export_system_includes bazel.StringListAttribute