compiler: share artifacts across build directories

compiler/compiler-cache.go

@@ -946,17 +946,15 @@ func (o *compilerCacheKeyOwner) keyedGoMod(file string, data []byte) []byte {
 
 // sharedIdentity digests the schema, the compiler identity and the request.
 // Override directories count by content, which decides the override facts the
-// parity check reads.
+// parity check reads. Protobuf binding roots count only through the bindings
+// each package reads (protobufSideInputs): a root outside every module would
+// key by its path from the request directory, which differs per build
+// directory, so programs that share packages would share no artifact.
 func (o *compilerCacheKeyOwner) sharedIdentity() string {
 	var b strings.Builder
 	writeKeyField(&b, "schema", compilerCacheSchema)
 	writeCompilerIdentity(&b)
 	req := o.req
-	if req.ProtobufTypeScriptBinding {
-		for _, root := range req.AdditionalBindingRoots {
-			writeKeyField(&b, "protobuf-binding-root", o.keyPath(root))
-		}
-	}
 	for _, flag := range goScriptBuildFlags(req.BuildFlags) {
 		writeKeyField(&b, "build-flag", flag)
 	}

compiler/compiler-cache_test.go

@@ -119,23 +119,26 @@ func TestCompilePackagesCacheReplaysAcrossCheckouts(t *testing.T) {
 
 // TestCompilePackagesCacheReplaysAcrossReplacedCheckouts pins that a go.mod
 // replacing a module with an absolute directory keys that directory by its
-// module, so a generated module in a second checkout still replays.
+// module, so a generated module in a second checkout still replays. The second
+// module sits deeper, as a build tool's per platform directory does, and both
+// name a protobuf binding root that holds no package of the graph.
 func TestCompilePackagesCacheReplaysAcrossReplacedCheckouts(t *testing.T) {
 	cacheRoot := filepath.Join(t.TempDir(), "cache")
-	checkout := func(outputName string) {
+	config := Config{ProtobufTypeScriptBinding: true, AdditionalBindingRoots: []string{t.TempDir()}}
+	checkout := func(outputName, appPath string) {
 		root := writePackageGraphFixture(t, map[string]string{
-			"lib/go.mod":  "module example.test/lib\n\ngo 1.25.3\n",
-			"lib/lib.go":  "package lib\nconst Name = \"lib\"\n",
-			"app/main.go": "package main\n\nimport \"example.test/lib\"\n\nfunc main() { println(lib.Name) }\n",
+			"lib/go.mod":           "module example.test/lib\n\ngo 1.25.3\n",
+			"lib/lib.go":           "package lib\nconst Name = \"lib\"\n",
+			appPath + "/main.go": "package main\n\nimport \"example.test/lib\"\n\nfunc main() { println(lib.Name) }\n",
 		})
-		appDir := filepath.Join(root, "app")
+		appDir := filepath.Join(root, appPath)
 		writeFixtureFile(t, appDir, "go.mod", "module example.test/app\n\ngo 1.25.3\n\nrequire example.test/lib v0.0.0\n\nreplace example.test/lib => "+filepath.Join(root, "lib")+"\n")
-		compileCacheFixture(t, appDir, filepath.Join(t.TempDir(), outputName), cacheRoot)
+		compileCacheFixtureConfig(t, config, appDir, filepath.Join(t.TempDir(), outputName), cacheRoot)
 	}
-	checkout("first")
+	checkout("first", "app")
 	manifests := countCacheManifests(t, cacheRoot)
 
-	checkout("second")
+	checkout("second", "web/js/app")
 	if got := countCacheManifests(t, cacheRoot); got != manifests {
 		t.Fatalf("cache manifests after second checkout = %d, want %d", got, manifests)
 	}