From ec6e9910e68ac792dcc66f0b3c568c6c51467415 Mon Sep 17 00:00:00 2001
From: Ivan Lozano <ivanlozano@google.com>
Date: Thu, 21 Jan 2021 15:23:29 -0500
Subject: [PATCH] rust: Depend on CC a shared library's TOC, not .so

CC libraries generate TOC files which contain the list of exported
symbols. By depending on the TOC file instead of the .so, changes to
shared library dependencies will not result in rebuilding Rust
dependencies as long as the exported symbols remain unchanged. This
should improve incremental build times during development.

This also includes a minor fix where exported linkObjects should be
deduplicated to avoid the same object being included many times.

Bug: 173619911
Test: m libkeystore2; modify a bionic file; m libkeystore2
      doesn't rebuild the rust target.
Change-Id: I6383217c125bf8dd7125a5e013a78754cac4edf2
---
 rust/builder.go |  2 +-
 rust/rust.go    | 27 ++++++++++++++++++---------
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/rust/builder.go b/rust/builder.go
index e5f0ab5e1..baeab69e9 100644
--- a/rust/builder.go
+++ b/rust/builder.go
@@ -188,7 +188,7 @@ func transformSrctoCrate(ctx ModuleContext, main android.Path, deps PathDeps, fl
 	implicits = append(implicits, rustLibsToPaths(deps.DyLibs)...)
 	implicits = append(implicits, rustLibsToPaths(deps.ProcMacros)...)
 	implicits = append(implicits, deps.StaticLibs...)
-	implicits = append(implicits, deps.SharedLibs...)
+	implicits = append(implicits, deps.SharedLibDeps...)
 	implicits = append(implicits, deps.srcProviderFiles...)
 
 	if deps.CrtBegin.Valid() {
diff --git a/rust/rust.go b/rust/rust.go
index 1fa97af96..83add87b7 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -267,14 +267,15 @@ type Deps struct {
 }
 
 type PathDeps struct {
-	DyLibs      RustLibraries
-	RLibs       RustLibraries
-	SharedLibs  android.Paths
-	StaticLibs  android.Paths
-	ProcMacros  RustLibraries
-	linkDirs    []string
-	depFlags    []string
-	linkObjects []string
+	DyLibs        RustLibraries
+	RLibs         RustLibraries
+	SharedLibs    android.Paths
+	SharedLibDeps android.Paths
+	StaticLibs    android.Paths
+	ProcMacros    RustLibraries
+	linkDirs      []string
+	depFlags      []string
+	linkObjects   []string
 	//ReexportedDeps android.Paths
 
 	// Used by bindgen modules which call clang
@@ -952,9 +953,15 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 		staticLibDepFiles = append(staticLibDepFiles, dep.OutputFile().Path())
 	}
 
+	var sharedLibFiles android.Paths
 	var sharedLibDepFiles android.Paths
 	for _, dep := range directSharedLibDeps {
-		sharedLibDepFiles = append(sharedLibDepFiles, dep.OutputFile().Path())
+		sharedLibFiles = append(sharedLibFiles, dep.OutputFile().Path())
+		if dep.Toc().Valid() {
+			sharedLibDepFiles = append(sharedLibDepFiles, dep.Toc().Path())
+		} else {
+			sharedLibDepFiles = append(sharedLibDepFiles, dep.OutputFile().Path())
+		}
 	}
 
 	var srcProviderDepFiles android.Paths
@@ -970,12 +977,14 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 	depPaths.RLibs = append(depPaths.RLibs, rlibDepFiles...)
 	depPaths.DyLibs = append(depPaths.DyLibs, dylibDepFiles...)
 	depPaths.SharedLibs = append(depPaths.SharedLibs, sharedLibDepFiles...)
+	depPaths.SharedLibDeps = append(depPaths.SharedLibDeps, sharedLibDepFiles...)
 	depPaths.StaticLibs = append(depPaths.StaticLibs, staticLibDepFiles...)
 	depPaths.ProcMacros = append(depPaths.ProcMacros, procMacroDepFiles...)
 	depPaths.SrcDeps = append(depPaths.SrcDeps, srcProviderDepFiles...)
 
 	// Dedup exported flags from dependencies
 	depPaths.linkDirs = android.FirstUniqueStrings(depPaths.linkDirs)
+	depPaths.linkObjects = android.FirstUniqueStrings(depPaths.linkObjects)
 	depPaths.depFlags = android.FirstUniqueStrings(depPaths.depFlags)
 	depPaths.depClangFlags = android.FirstUniqueStrings(depPaths.depClangFlags)
 	depPaths.depIncludePaths = android.FirstUniquePaths(depPaths.depIncludePaths)