clang_generator: Collect function types directly

Do not try to peel off all layers of pointers/references when collecting
types, recursion works well here. Also collect the function type itself,
even if it is a pointer or if the function was the underlying type of a
typedef.

PiperOrigin-RevId: 490475937
Change-Id: I13cb3d9d3de7d25b9e627f43112c46758c7e6a22

sandboxed_api/tools/clang_generator/emitter_test.cc

@@ -105,6 +105,25 @@ TEST_F(EmitterTest, RelatedTypes) {
                           "typedef struct { int member; } MyStruct"));
 }
 
+TEST_F(EmitterTest, CollectFunctionPointer) {
+  EmitterForTesting emitter;
+  EXPECT_THAT(
+      RunFrontendAction(
+          R"(typedef void (callback_t)(void*);
+             struct HandlerData {
+               int member;
+               callback_t* cb;
+             };
+             extern "C" int Structize(HandlerData*);)",
+          std::make_unique<GeneratorAction>(emitter, GeneratorOptions())),
+      IsOk());
+  EXPECT_THAT(emitter.GetRenderedFunctions(), SizeIs(1));
+
+  EXPECT_THAT(
+      UglifyAll(emitter.SpellingsForNS("")),
+      ElementsAre("struct HandlerData { int member; callback_t *cb; }"));
+}
+
 TEST_F(EmitterTest, TypedefNames) {
   EmitterForTesting emitter;
   ASSERT_THAT(

sandboxed_api/tools/clang_generator/types.cc

@@ -61,22 +61,19 @@ void TypeCollector::CollectRelatedTypes(clang::QualType qual) {
       qual->isMemberFunctionPointerType()) {
     if (const auto* function_type = qual->getPointeeOrArrayElementType()
                                         ->getAs<clang::FunctionProtoType>()) {
-      // Note: Do not add the function type itself, as this will always be a
+      // Collect the return type, the parameter types as well as the function
-      //       pointer argument. We only need to collect all its related types.
+      // pointer type itself.
       CollectRelatedTypes(function_type->getReturnType());
       for (const clang::QualType& param : function_type->getParamTypes()) {
         CollectRelatedTypes(param);
       }
+      collected_.insert(qual);
       return;
     }
   }
 
   if (IsPointerOrReference(qual)) {
-    clang::QualType pointee = qual;
+    CollectRelatedTypes(qual->getPointeeType());
-    do {
-      pointee = pointee->getPointeeType();
-    } while (IsPointerOrReference(pointee));
-    CollectRelatedTypes(pointee);
     return;
   }