Add support for custom bindgen binaries.

In some cases customized logic is required to generate the expected
bindgen bindings. This adds support for rust_bindgen modules to define a
HostTool module to use instead of bindgen.

Bug: 161816141
Test: New Soong tests pass.
Test: Local test case shows custom_binary module being used for bindgen
      generation.

Change-Id: Id52aec4f25c38206d7e585d8e662be7836aa1d4b

1 files changed, 12 insertions, 4 deletions

diff --git a/rust/rust.go b/rust/rust.go
index 01952477e..7ec2d736b 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -722,10 +722,11 @@ type dependencyTag struct {
 }
 
 var (
-	rlibDepTag       = dependencyTag{name: "rlibTag", library: true}
-	dylibDepTag      = dependencyTag{name: "dylib", library: true}
-	procMacroDepTag  = dependencyTag{name: "procMacro", proc_macro: true}
-	testPerSrcDepTag = dependencyTag{name: "rust_unit_tests"}
+	customBindgenDepTag = dependencyTag{name: "customBindgenTag"}
+	rlibDepTag          = dependencyTag{name: "rlibTag", library: true}
+	dylibDepTag         = dependencyTag{name: "dylib", library: true}
+	procMacroDepTag     = dependencyTag{name: "procMacro", proc_macro: true}
+	testPerSrcDepTag    = dependencyTag{name: "rust_unit_tests"}
 )
 
 type autoDep struct {
@@ -1009,6 +1010,13 @@ func (mod *Module) DepsMutator(actx android.BottomUpMutatorContext) {
 		actx.AddVariationDependencies(commonDepVariations, cc.CrtEndDepTag, deps.CrtEnd)
 	}
 
+	if mod.sourceProvider != nil {
+		if bindgen, ok := mod.sourceProvider.(*bindgenDecorator); ok &&
+			bindgen.Properties.Custom_bindgen != "" {
+			actx.AddFarVariationDependencies(ctx.Config().BuildOSTarget.Variations(), customBindgenDepTag,
+				bindgen.Properties.Custom_bindgen)
+		}
+	}
 	// proc_macros are compiler plugins, and so we need the host arch variant as a dependendcy.
 	actx.AddFarVariationDependencies(ctx.Config().BuildOSTarget.Variations(), procMacroDepTag, deps.ProcMacros...)
 }