[DebugInfo] Fix debug info round tripping of types inside functions

Types with @_originallyDefinedIn cannot be round tripped,

Types declared inside functions have their mangling affected by the
function signature. If the generic signature mentions an
@_originallyDefinedIn type, the type inside the function cannot be round
tripped either.

This commit disables round tripping for this scenario.

Author: augusto2112

lib/IRGen/IRGenDebugInfo.cpp

@@ -25,6 +25,7 @@
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/Attr.h"
 #include "swift/AST/Decl.h"
+#include "swift/AST/DeclContext.h"
 #include "swift/AST/Expr.h"
 #include "swift/AST/GenericEnvironment.h"
 #include "swift/AST/IRGenOptions.h"
@@ -34,6 +35,7 @@
 #include "swift/AST/Pattern.h"
 #include "swift/AST/TypeDifferenceVisitor.h"
 #include "swift/AST/TypeWalker.h"
+#include "swift/AST/Types.h"
 #include "swift/Basic/Assertions.h"
 #include "swift/Basic/Compiler.h"
 #include "swift/Basic/SourceManager.h"
@@ -65,6 +67,7 @@
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileSystem.h"
@@ -2343,11 +2346,16 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       if (visitedOriginallyDefinedIn)
         return TypeWalker::Action::Stop;
 
-      // A typealias inside a function used that function's signature as part of
+      DeclContext *D = nullptr;
+      if (auto *TAT = llvm::dyn_cast<TypeAliasType>(T))
+        D = TAT->getDecl()->getDeclContext();
+      else if (auto *NT = llvm::dyn_cast<NominalOrBoundGenericNominalType>(T))
+        D = NT->getDecl()->getDeclContext();
+
+      // A type inside a function uses that function's signature as part of
       // its mangling, so check if any types in the generic signature are
       // annotated with @_originallyDefinedIn.
-      if (auto *TAT = llvm::dyn_cast<TypeAliasType>(T)) {
-        auto D = TAT->getDecl()->getDeclContext();
+      if (D) {
         if (auto AFD = llvm::dyn_cast<AbstractFunctionDecl>(D)) {
           OriginallyDefinedInFinder InnerWalker;
           AFD->getInterfaceType().walk(InnerWalker);

test/DebugInfo/local_type_originally_defined_in.swift

@@ -21,6 +21,19 @@ public func localTypeAliasTest(horse: Horse) {
   // CHECK: DIDerivedType(tag: DW_TAG_typedef, name: "$s32local_type_originally_defined_in0A13TypeAliasTest5horsey4Barn5HorseV_tF1AL_aD"
 }
 
+
+public func localTypeTest(horse: Horse) {
+  // The local type mangling for 'A' mentions 'Horse', which must
+  // be mangled using it's current module name, and not the
+  // original module name, for consistency with the debug info
+  // mangling.
+  struct LocalStruct {}
+
+  let info = UnsafeMutablePointer<LocalStruct>.allocate(capacity: 1)
+  _ = info
+  // CHECK: DICompositeType(tag: DW_TAG_structure_type, name: "$s32local_type_originally_defined_in0A8TypeTest5horsey4Barn5HorseV_tF11LocalStructL_VD"
+}
+
 public func localTypeAliasTest() -> Horse {
   typealias B = Int