Merge "Add tidy.md document"
diff --git a/cc/OWNERS b/cc/OWNERS
index a7e6ebb..a438b15 100644
--- a/cc/OWNERS
+++ b/cc/OWNERS
@@ -1,4 +1,4 @@
 per-file ndk_*.go = danalbert@google.com
 per-file tidy.go = srhines@google.com, chh@google.com
 per-file afdo.go,afdo_test.go,lto.go,pgo.go = srhines@google.com, pirama@google.com, yikong@google.com
-
+per-file coverage.go = pirama@google.com, srhines@google.com, allenhair@google.com
diff --git a/cc/coverage.go b/cc/coverage.go
index 8dd2db1..f2b5425 100644
--- a/cc/coverage.go
+++ b/cc/coverage.go
@@ -98,6 +98,9 @@
 		} else if clangCoverage {
 			flags.Local.CommonFlags = append(flags.Local.CommonFlags, profileInstrFlag,
 				"-fcoverage-mapping", "-Wno-pass-failed", "-D__ANDROID_CLANG_COVERAGE__")
+			// Override -Wframe-larger-than.  We can expect frame size increase after
+			// coverage instrumentation.
+			flags.Local.CFlags = append(flags.Local.CFlags, "-Wno-frame-larger-than=")
 		}
 	}
 
diff --git a/cc/sanitize.go b/cc/sanitize.go
index a054c91..6c68822 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -42,7 +42,6 @@
 		"-fno-omit-frame-pointer",
 		"-Wno-frame-larger-than=",
 		"-fsanitize-hwaddress-abi=platform",
-		"-mllvm", "-hwasan-use-after-scope=1",
 	}
 
 	// ThinLTO performs codegen during link time, thus these flags need to
diff --git a/rust/binary.go b/rust/binary.go
index db91ccb..0dc320e 100644
--- a/rust/binary.go
+++ b/rust/binary.go
@@ -92,14 +92,23 @@
 func (binary *binaryDecorator) compilerDeps(ctx DepsContext, deps Deps) Deps {
 	deps = binary.baseCompiler.compilerDeps(ctx, deps)
 
+	static := Bool(binary.Properties.Static_executable)
 	if ctx.toolchain().Bionic() {
-		deps = bionicDeps(ctx, deps, Bool(binary.Properties.Static_executable))
-		if Bool(binary.Properties.Static_executable) {
-			deps.CrtBegin = "crtbegin_static"
+		deps = bionicDeps(ctx, deps, static)
+		if static {
+			deps.CrtBegin = []string{"crtbegin_static"}
 		} else {
-			deps.CrtBegin = "crtbegin_dynamic"
+			deps.CrtBegin = []string{"crtbegin_dynamic"}
 		}
-		deps.CrtEnd = "crtend_android"
+		deps.CrtEnd = []string{"crtend_android"}
+	} else if ctx.Os() == android.LinuxMusl {
+		deps = muslDeps(ctx, deps, static)
+		if static {
+			deps.CrtBegin = []string{"libc_musl_crtbegin_static"}
+		} else {
+			deps.CrtBegin = []string{"libc_musl_crtbegin_dynamic", "musl_linker_script"}
+		}
+		deps.CrtEnd = []string{"libc_musl_crtend"}
 	}
 
 	return deps
diff --git a/rust/bindgen.go b/rust/bindgen.go
index ef5702b..f4c337d 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -288,6 +288,8 @@
 	deps = b.BaseSourceProvider.SourceProviderDeps(ctx, deps)
 	if ctx.toolchain().Bionic() {
 		deps = bionicDeps(ctx, deps, false)
+	} else if ctx.Os() == android.LinuxMusl {
+		deps = muslDeps(ctx, deps, false)
 	}
 
 	deps.SharedLibs = append(deps.SharedLibs, b.ClangProperties.Shared_libs...)
diff --git a/rust/builder.go b/rust/builder.go
index e66a6f0..00035b9 100644
--- a/rust/builder.go
+++ b/rust/builder.go
@@ -247,9 +247,8 @@
 	implicits = append(implicits, deps.srcProviderFiles...)
 	implicits = append(implicits, deps.AfdoProfiles...)
 
-	if deps.CrtBegin.Valid() {
-		implicits = append(implicits, deps.CrtBegin.Path(), deps.CrtEnd.Path())
-	}
+	implicits = append(implicits, deps.CrtBegin...)
+	implicits = append(implicits, deps.CrtEnd...)
 
 	if len(deps.SrcDeps) > 0 {
 		moduleGenDir := ctx.RustModule().compiler.CargoOutDir()
@@ -319,8 +318,8 @@
 			"rustcFlags": strings.Join(rustcFlags, " "),
 			"linkFlags":  strings.Join(linkFlags, " "),
 			"libFlags":   strings.Join(libFlags, " "),
-			"crtBegin":   deps.CrtBegin.String(),
-			"crtEnd":     deps.CrtEnd.String(),
+			"crtBegin":   strings.Join(deps.CrtBegin.Strings(), " "),
+			"crtEnd":     strings.Join(deps.CrtEnd.Strings(), " "),
 			"envVars":    strings.Join(envVars, " "),
 		},
 	})
diff --git a/rust/compiler.go b/rust/compiler.go
index 3040e5d..c5d40f4 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -364,7 +364,7 @@
 	if !Bool(compiler.Properties.No_stdlibs) {
 		for _, stdlib := range config.Stdlibs {
 			// If we're building for the build host, use the prebuilt stdlibs
-			if ctx.Target().Os == ctx.Config().BuildOS {
+			if ctx.Target().Os == android.Linux || ctx.Target().Os == android.Darwin {
 				stdlib = "prebuilt_" + stdlib
 			}
 			deps.Stdlibs = append(deps.Stdlibs, stdlib)
@@ -394,6 +394,20 @@
 	return deps
 }
 
+func muslDeps(ctx DepsContext, deps Deps, static bool) Deps {
+	muslLibs := []string{"libc_musl"}
+	if static {
+		deps.StaticLibs = append(deps.StaticLibs, muslLibs...)
+	} else {
+		deps.SharedLibs = append(deps.SharedLibs, muslLibs...)
+	}
+	if libRuntimeBuiltins := config.BuiltinsRuntimeLibrary(ctx.toolchain()); libRuntimeBuiltins != "" {
+		deps.StaticLibs = append(deps.StaticLibs, libRuntimeBuiltins)
+	}
+
+	return deps
+}
+
 func (compiler *baseCompiler) crateName() string {
 	return compiler.Properties.Crate_name
 }
diff --git a/rust/config/x86_linux_host.go b/rust/config/x86_linux_host.go
index c10afd8..7608349 100644
--- a/rust/config/x86_linux_host.go
+++ b/rust/config/x86_linux_host.go
@@ -22,12 +22,29 @@
 
 var (
 	LinuxRustFlags     = []string{}
+	LinuxMuslRustFlags = []string{
+		// disable rustc's builtin fallbacks for crt objects
+		"-C link_self_contained=no",
+		// force rustc to use a dynamic musl libc
+		"-C target-feature=-crt-static",
+		"-Z link-native-libraries=no",
+	}
 	LinuxRustLinkFlags = []string{
 		"-B${cc_config.ClangBin}",
 		"-fuse-ld=lld",
 		"-Wl,--undefined-version",
+	}
+	LinuxRustGlibcLinkFlags = []string{
 		"--sysroot ${cc_config.LinuxGccRoot}/sysroot",
 	}
+	LinuxRustMuslLinkFlags = []string{
+		"--sysroot /dev/null",
+		"-nodefaultlibs",
+		"-nostdlib",
+		"-Wl,--no-dynamic-linker",
+		// for unwind
+		"-lgcc", "-lgcc_eh",
+	}
 	linuxX86Rustflags   = []string{}
 	linuxX86Linkflags   = []string{}
 	linuxX8664Rustflags = []string{}
@@ -35,15 +52,17 @@
 )
 
 func init() {
-	registerToolchainFactory(android.Linux, android.X86_64, linuxX8664ToolchainFactory)
-	registerToolchainFactory(android.Linux, android.X86, linuxX86ToolchainFactory)
+	registerToolchainFactory(android.Linux, android.X86_64, linuxGlibcX8664ToolchainFactory)
+	registerToolchainFactory(android.Linux, android.X86, linuxGlibcX86ToolchainFactory)
 
-	// TODO: musl rust support
-	registerToolchainFactory(android.LinuxMusl, android.X86_64, linuxX8664ToolchainFactory)
-	registerToolchainFactory(android.LinuxMusl, android.X86, linuxX86ToolchainFactory)
+	registerToolchainFactory(android.LinuxMusl, android.X86_64, linuxMuslX8664ToolchainFactory)
+	registerToolchainFactory(android.LinuxMusl, android.X86, linuxMuslX86ToolchainFactory)
 
 	pctx.StaticVariable("LinuxToolchainRustFlags", strings.Join(LinuxRustFlags, " "))
+	pctx.StaticVariable("LinuxMuslToolchainRustFlags", strings.Join(LinuxMuslRustFlags, " "))
 	pctx.StaticVariable("LinuxToolchainLinkFlags", strings.Join(LinuxRustLinkFlags, " "))
+	pctx.StaticVariable("LinuxGlibcToolchainLinkFlags", strings.Join(LinuxRustGlibcLinkFlags, " "))
+	pctx.StaticVariable("LinuxMuslToolchainLinkFlags", strings.Join(LinuxRustMuslLinkFlags, " "))
 	pctx.StaticVariable("LinuxToolchainX86RustFlags", strings.Join(linuxX86Rustflags, " "))
 	pctx.StaticVariable("LinuxToolchainX86LinkFlags", strings.Join(linuxX86Linkflags, " "))
 	pctx.StaticVariable("LinuxToolchainX8664RustFlags", strings.Join(linuxX8664Rustflags, " "))
@@ -51,19 +70,9 @@
 
 }
 
-type toolchainLinux struct {
-	toolchainRustFlags string
-	toolchainLinkFlags string
-}
-
-type toolchainLinuxX86 struct {
-	toolchain32Bit
-	toolchainLinux
-}
-
+// Base 64-bit linux rust toolchain
 type toolchainLinuxX8664 struct {
 	toolchain64Bit
-	toolchainLinux
 }
 
 func (toolchainLinuxX8664) Supported() bool {
@@ -78,10 +87,6 @@
 	return "x86_64"
 }
 
-func (t *toolchainLinuxX8664) RustTriple() string {
-	return "x86_64-unknown-linux-gnu"
-}
-
 func (t *toolchainLinuxX8664) ToolchainLinkFlags() string {
 	// Prepend the lld flags from cc_config so we stay in sync with cc
 	return "${cc_config.LinuxLldflags} ${cc_config.LinuxX8664Lldflags} " +
@@ -92,8 +97,49 @@
 	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainX8664RustFlags}"
 }
 
-func linuxX8664ToolchainFactory(arch android.Arch) Toolchain {
-	return toolchainLinuxX8664Singleton
+// Specialization of the 64-bit linux rust toolchain for glibc.  Adds the gnu rust triple and
+// sysroot linker flags.
+type toolchainLinuxGlibcX8664 struct {
+	toolchainLinuxX8664
+}
+
+func (t *toolchainLinuxX8664) RustTriple() string {
+	return "x86_64-unknown-linux-gnu"
+}
+
+func (t *toolchainLinuxGlibcX8664) ToolchainLinkFlags() string {
+	return t.toolchainLinuxX8664.ToolchainLinkFlags() + " " + "${config.LinuxGlibcToolchainLinkFlags}"
+}
+
+func linuxGlibcX8664ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxGlibcX8664Singleton
+}
+
+// Specialization of the 64-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslX8664 struct {
+	toolchainLinuxX8664
+}
+
+func (t *toolchainLinuxMuslX8664) RustTriple() string {
+	return "x86_64-unknown-linux-musl"
+}
+
+func (t *toolchainLinuxMuslX8664) ToolchainLinkFlags() string {
+	return t.toolchainLinuxX8664.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslX8664) ToolchainRustFlags() string {
+	return t.toolchainLinuxX8664.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslX8664ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslX8664Singleton
+}
+
+// Base 32-bit linux rust toolchain
+type toolchainLinuxX86 struct {
+	toolchain32Bit
 }
 
 func (toolchainLinuxX86) Supported() bool {
@@ -116,10 +162,6 @@
 	return "x86_64"
 }
 
-func (t *toolchainLinuxX86) RustTriple() string {
-	return "i686-unknown-linux-gnu"
-}
-
 func (t *toolchainLinuxX86) ToolchainLinkFlags() string {
 	// Prepend the lld flags from cc_config so we stay in sync with cc
 	return "${cc_config.LinuxLldflags} ${cc_config.LinuxX86Lldflags} " +
@@ -130,9 +172,47 @@
 	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainX86RustFlags}"
 }
 
-func linuxX86ToolchainFactory(arch android.Arch) Toolchain {
-	return toolchainLinuxX86Singleton
+// Specialization of the 32-bit linux rust toolchain for glibc.  Adds the gnu rust triple and
+// sysroot linker flags.
+type toolchainLinuxGlibcX86 struct {
+	toolchainLinuxX86
 }
 
-var toolchainLinuxX8664Singleton Toolchain = &toolchainLinuxX8664{}
-var toolchainLinuxX86Singleton Toolchain = &toolchainLinuxX86{}
+func (t *toolchainLinuxGlibcX86) RustTriple() string {
+	return "i686-unknown-linux-gnu"
+}
+
+func (t *toolchainLinuxGlibcX86) ToolchainLinkFlags() string {
+	return t.toolchainLinuxX86.ToolchainLinkFlags() + " " + "${config.LinuxGlibcToolchainLinkFlags}"
+}
+
+func linuxGlibcX86ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxGlibcX86Singleton
+}
+
+// Specialization of the 32-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslX86 struct {
+	toolchainLinuxX86
+}
+
+func (t *toolchainLinuxMuslX86) RustTriple() string {
+	return "i686-unknown-linux-musl"
+}
+
+func (t *toolchainLinuxMuslX86) ToolchainLinkFlags() string {
+	return t.toolchainLinuxX86.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslX86) ToolchainRustFlags() string {
+	return t.toolchainLinuxX86.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslX86ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslX86Singleton
+}
+
+var toolchainLinuxGlibcX8664Singleton Toolchain = &toolchainLinuxGlibcX8664{}
+var toolchainLinuxGlibcX86Singleton Toolchain = &toolchainLinuxGlibcX86{}
+var toolchainLinuxMuslX8664Singleton Toolchain = &toolchainLinuxMuslX8664{}
+var toolchainLinuxMuslX86Singleton Toolchain = &toolchainLinuxMuslX86{}
diff --git a/rust/library.go b/rust/library.go
index bb2e83f..baac3f0 100644
--- a/rust/library.go
+++ b/rust/library.go
@@ -426,10 +426,16 @@
 func (library *libraryDecorator) compilerDeps(ctx DepsContext, deps Deps) Deps {
 	deps = library.baseCompiler.compilerDeps(ctx, deps)
 
-	if ctx.toolchain().Bionic() && (library.dylib() || library.shared()) {
-		deps = bionicDeps(ctx, deps, false)
-		deps.CrtBegin = "crtbegin_so"
-		deps.CrtEnd = "crtend_so"
+	if library.dylib() || library.shared() {
+		if ctx.toolchain().Bionic() {
+			deps = bionicDeps(ctx, deps, false)
+			deps.CrtBegin = []string{"crtbegin_so"}
+			deps.CrtEnd = []string{"crtend_so"}
+		} else if ctx.Os() == android.LinuxMusl {
+			deps = muslDeps(ctx, deps, false)
+			deps.CrtBegin = []string{"libc_musl_crtbegin_so"}
+			deps.CrtEnd = []string{"libc_musl_crtend_so"}
+		}
 	}
 
 	return deps
diff --git a/rust/rust.go b/rust/rust.go
index 0f7b768..018d1dd 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -394,7 +394,7 @@
 	DataLibs []string
 	DataBins []string
 
-	CrtBegin, CrtEnd string
+	CrtBegin, CrtEnd []string
 }
 
 type PathDeps struct {
@@ -421,8 +421,8 @@
 	depGeneratedHeaders   android.Paths
 	depSystemIncludePaths android.Paths
 
-	CrtBegin android.OptionalPath
-	CrtEnd   android.OptionalPath
+	CrtBegin android.Paths
+	CrtEnd   android.Paths
 
 	// Paths to generated source files
 	SrcDeps          android.Paths
@@ -1224,9 +1224,9 @@
 				depPaths.depSystemIncludePaths = append(depPaths.depSystemIncludePaths, exportedInfo.SystemIncludeDirs...)
 				depPaths.depGeneratedHeaders = append(depPaths.depGeneratedHeaders, exportedInfo.GeneratedHeaders...)
 			case depTag == cc.CrtBeginDepTag:
-				depPaths.CrtBegin = linkObject
+				depPaths.CrtBegin = append(depPaths.CrtBegin, linkObject.Path())
 			case depTag == cc.CrtEndDepTag:
-				depPaths.CrtEnd = linkObject
+				depPaths.CrtEnd = append(depPaths.CrtEnd, linkObject.Path())
 			}
 
 			// Make sure these dependencies are propagated
@@ -1234,6 +1234,13 @@
 				lib.exportLinkDirs(linkPath)
 				lib.exportLinkObjects(linkObject.String())
 			}
+		} else {
+			switch {
+			case depTag == cc.CrtBeginDepTag:
+				depPaths.CrtBegin = append(depPaths.CrtBegin, android.OutputFileForModule(ctx, dep, ""))
+			case depTag == cc.CrtEndDepTag:
+				depPaths.CrtEnd = append(depPaths.CrtEnd, android.OutputFileForModule(ctx, dep, ""))
+			}
 		}
 
 		if srcDep, ok := dep.(android.SourceFileProducer); ok {
@@ -1432,13 +1439,13 @@
 	actx.AddVariationDependencies(nil, cc.HeaderDepTag(), deps.HeaderLibs...)
 
 	crtVariations := cc.GetCrtVariations(ctx, mod)
-	if deps.CrtBegin != "" {
+	for _, crt := range deps.CrtBegin {
 		actx.AddVariationDependencies(crtVariations, cc.CrtBeginDepTag,
-			cc.RewriteSnapshotLib(deps.CrtBegin, cc.GetSnapshot(mod, &snapshotInfo, actx).Objects))
+			cc.RewriteSnapshotLib(crt, cc.GetSnapshot(mod, &snapshotInfo, actx).Objects))
 	}
-	if deps.CrtEnd != "" {
+	for _, crt := range deps.CrtEnd {
 		actx.AddVariationDependencies(crtVariations, cc.CrtEndDepTag,
-			cc.RewriteSnapshotLib(deps.CrtEnd, cc.GetSnapshot(mod, &snapshotInfo, actx).Objects))
+			cc.RewriteSnapshotLib(crt, cc.GetSnapshot(mod, &snapshotInfo, actx).Objects))
 	}
 
 	if mod.sourceProvider != nil {