commit f1ff54a10b4abc248b0cfcc5d3c1ebbf534522c5
author Thiébaud Weksteen <tweek@google.com> Mon Mar 22 14:24:54 2021 +0100
committer Thiébaud Weksteen <tweek@google.com> Tue Mar 23 13:55:40 2021 +0100
tree a93b7286a7db48bccec791d2a0c21691db8cdab0
parent 50e49818a3339039faf6c3142db7da175770b486

rust: Drop libgcc dependency

Rustc unstable option "link-native-libraries" is used to prevent the
linkage of other libraries via the #[link] directive. Add a dependency
to libclang_rt.builtins, similarly to cc.

Bug: 141331117
Test: lunch aosp_crosshatch-userdebug; m
Change-Id: I5c232291a5dd08a99e6a12a1295e30bb8e4fcaf1

rust/binary.go

diff --git a/rust/binary.go b/rust/binary.go
index df48916..dfe8744 100644
--- a/rust/binary.go
+++ b/rust/binary.go
@@ -87,7 +87,7 @@
 	deps = binary.baseCompiler.compilerDeps(ctx, deps)
 
 	if ctx.toolchain().Bionic() {
-		deps = bionicDeps(deps, Bool(binary.Properties.Static_executable))
+		deps = bionicDeps(ctx, deps, Bool(binary.Properties.Static_executable))
 		if Bool(binary.Properties.Static_executable) {
 			deps.CrtBegin = "crtbegin_static"
 		} else {

rust/bindgen.go

diff --git a/rust/bindgen.go b/rust/bindgen.go
index db69e23..bcc26b8 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -260,7 +260,7 @@
 func (b *bindgenDecorator) SourceProviderDeps(ctx DepsContext, deps Deps) Deps {
 	deps = b.BaseSourceProvider.SourceProviderDeps(ctx, deps)
 	if ctx.toolchain().Bionic() {
-		deps = bionicDeps(deps, false)
+		deps = bionicDeps(ctx, deps, false)
 	}
 
 	deps.SharedLibs = append(deps.SharedLibs, b.ClangProperties.Shared_libs...)

rust/compiler.go

diff --git a/rust/compiler.go b/rust/compiler.go
index 98ad7ad..200af90 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -281,7 +281,7 @@
 	return deps
 }
 
-func bionicDeps(deps Deps, static bool) Deps {
+func bionicDeps(ctx DepsContext, deps Deps, static bool) Deps {
 	bionicLibs := []string{}
 	bionicLibs = append(bionicLibs, "liblog")
 	bionicLibs = append(bionicLibs, "libc")
@@ -294,9 +294,9 @@
 		deps.SharedLibs = append(deps.SharedLibs, bionicLibs...)
 	}
 
-	//TODO(b/141331117) libstd requires libgcc on Android
-	deps.StaticLibs = append(deps.StaticLibs, "libgcc")
-
+	if libRuntimeBuiltins := config.BuiltinsRuntimeLibrary(ctx.toolchain()); libRuntimeBuiltins != "" {
+		deps.StaticLibs = append(deps.StaticLibs, libRuntimeBuiltins)
+	}
 	return deps
 }
 

rust/config/global.go

diff --git a/rust/config/global.go b/rust/config/global.go
index 12f4972..9208ddb 100644
--- a/rust/config/global.go
+++ b/rust/config/global.go
@@ -53,6 +53,7 @@
 
 	deviceGlobalRustFlags = []string{
 		"-C panic=abort",
+		"-Z link-native-libraries=no",
 	}
 
 	deviceGlobalLinkFlags = []string{
@@ -62,7 +63,7 @@
 		// Override cc's --no-undefined-version to allow rustc's generated alloc functions
 		"-Wl,--undefined-version",
 
-		"-Bdynamic",
+		"-Wl,-Bdynamic",
 		"-nostdlib",
 		"-Wl,--pack-dyn-relocs=android+relr",
 		"-Wl,--use-android-relr-tags",

rust/config/toolchain.go

diff --git a/rust/config/toolchain.go b/rust/config/toolchain.go
index 9525c38..a769f12 100644
--- a/rust/config/toolchain.go
+++ b/rust/config/toolchain.go
@@ -112,6 +112,10 @@
 	return ""
 }
 
+func BuiltinsRuntimeLibrary(t Toolchain) string {
+	return LibclangRuntimeLibrary(t, "builtins")
+}
+
 func LibFuzzerRuntimeLibrary(t Toolchain) string {
 	return LibclangRuntimeLibrary(t, "fuzzer")
 }

rust/library.go

diff --git a/rust/library.go b/rust/library.go
index 7ff13ec..71fe1f5 100644
--- a/rust/library.go
+++ b/rust/library.go
@@ -404,7 +404,7 @@
 	deps = library.baseCompiler.compilerDeps(ctx, deps)
 
 	if ctx.toolchain().Bionic() && (library.dylib() || library.shared()) {
-		deps = bionicDeps(deps, false)
+		deps = bionicDeps(ctx, deps, false)
 		deps.CrtBegin = "crtbegin_so"
 		deps.CrtEnd = "crtend_so"
 	}