Merge pull request swiftlang#41286 from jckarter/opaque-type-repeat-application-with-different-substitutions

Don't terminate ReplaceOpaqueTypesWithUnderlyingTypes if same opaque type is substituted with different substitution arguments.

Author: jckarter

include/swift/AST/Types.h

@@ -5673,9 +5673,12 @@ enum class OpaqueSubstitutionKind {
 /// archetypes with underlying types visible at a given resilience expansion
 /// to their underlying types.
 class ReplaceOpaqueTypesWithUnderlyingTypes {
+public:
+  using SeenDecl = std::pair<OpaqueTypeDecl *, SubstitutionMap>;
+private:
   ResilienceExpansion contextExpansion;
   llvm::PointerIntPair<const DeclContext *, 1, bool> inContextAndIsWholeModule;
-  llvm::SmallPtrSetImpl<OpaqueTypeDecl *> *seenDecls;
+  llvm::DenseSet<SeenDecl> *seenDecls;
 
 public:
   ReplaceOpaqueTypesWithUnderlyingTypes(const DeclContext *inContext,
@@ -5687,7 +5690,7 @@ class ReplaceOpaqueTypesWithUnderlyingTypes {
 
   ReplaceOpaqueTypesWithUnderlyingTypes(
       const DeclContext *inContext, ResilienceExpansion contextExpansion,
-      bool isWholeModuleContext, llvm::SmallPtrSetImpl<OpaqueTypeDecl *> &seen);
+      bool isWholeModuleContext, llvm::DenseSet<SeenDecl> &seen);
 
   /// TypeSubstitutionFn
   Type operator()(SubstitutableType *maybeOpaqueType) const;

lib/AST/Type.cpp

@@ -3502,7 +3502,8 @@ ReplaceOpaqueTypesWithUnderlyingTypes::shouldPerformSubstitution(
 
 static Type substOpaqueTypesWithUnderlyingTypesRec(
     Type ty, const DeclContext *inContext, ResilienceExpansion contextExpansion,
-    bool isWholeModuleContext, SmallPtrSetImpl<OpaqueTypeDecl *> &decls) {
+    bool isWholeModuleContext,
+    llvm::DenseSet<ReplaceOpaqueTypesWithUnderlyingTypes::SeenDecl> &decls) {
   ReplaceOpaqueTypesWithUnderlyingTypes replacer(inContext, contextExpansion,
                                                  isWholeModuleContext, decls);
   return ty.subst(replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes);
@@ -3566,7 +3567,7 @@ static bool canSubstituteTypeInto(Type ty, const DeclContext *dc,
 
 ReplaceOpaqueTypesWithUnderlyingTypes::ReplaceOpaqueTypesWithUnderlyingTypes(
     const DeclContext *inContext, ResilienceExpansion contextExpansion,
-    bool isWholeModuleContext, llvm::SmallPtrSetImpl<OpaqueTypeDecl *> &seen)
+    bool isWholeModuleContext, llvm::DenseSet<SeenDecl> &seen)
     : contextExpansion(contextExpansion),
       inContextAndIsWholeModule(inContext, isWholeModuleContext),
       seenDecls(&seen) {}
@@ -3618,24 +3619,25 @@ operator()(SubstitutableType *maybeOpaqueType) const {
 
   // If the type changed, but still contains opaque types, recur.
   if (!substTy->isEqual(maybeOpaqueType) && substTy->hasOpaqueArchetype()) {
+    SeenDecl seenKey(opaqueRoot->getDecl(), opaqueRoot->getSubstitutions());
     if (auto *alreadySeen = this->seenDecls) {
       // Detect substitution loops. If we find one, just bounce the original
       // type back to the caller. This substitution will fail at runtime
       // instead.
-      if (!alreadySeen->insert(opaqueRoot->getDecl()).second) {
+      if (!alreadySeen->insert(seenKey).second) {
         return maybeOpaqueType;
       }
 
       auto res = ::substOpaqueTypesWithUnderlyingTypesRec(
           substTy, inContext, contextExpansion, isContextWholeModule,
           *alreadySeen);
-      alreadySeen->erase(opaqueRoot->getDecl());
+      alreadySeen->erase(seenKey);
       return res;
     } else {
       // We're the top of the stack for the recursion check. Allocate a set of
       // opaque result type decls we've already seen for the rest of the check.
-      SmallPtrSet<OpaqueTypeDecl *, 8> seenDecls;
-      seenDecls.insert(opaqueRoot->getDecl());
+      llvm::DenseSet<SeenDecl> seenDecls;
+      seenDecls.insert(seenKey);
       return ::substOpaqueTypesWithUnderlyingTypesRec(
           substTy, inContext, contextExpansion, isContextWholeModule,
           seenDecls);
@@ -3648,7 +3650,7 @@ operator()(SubstitutableType *maybeOpaqueType) const {
 static ProtocolConformanceRef substOpaqueTypesWithUnderlyingTypesRec(
     ProtocolConformanceRef ref, Type origType, const DeclContext *inContext,
     ResilienceExpansion contextExpansion, bool isWholeModuleContext,
-    SmallPtrSetImpl<OpaqueTypeDecl *> &decls) {
+    llvm::DenseSet<ReplaceOpaqueTypesWithUnderlyingTypes::SeenDecl> &decls) {
   ReplaceOpaqueTypesWithUnderlyingTypes replacer(inContext, contextExpansion,
                                                  isWholeModuleContext, decls);
   return ref.subst(origType, replacer, replacer,
@@ -3732,24 +3734,26 @@ operator()(CanType maybeOpaqueType, Type replacementType,
 
   // If the type still contains opaque types, recur.
   if (substTy->hasOpaqueArchetype()) {
+    SeenDecl seenKey(opaqueRoot->getDecl(), opaqueRoot->getSubstitutions());
+    
     if (auto *alreadySeen = this->seenDecls) {
       // Detect substitution loops. If we find one, just bounce the original
       // type back to the caller. This substitution will fail at runtime
       // instead.
-      if (!alreadySeen->insert(opaqueRoot->getDecl()).second) {
+      if (!alreadySeen->insert(seenKey).second) {
         return abstractRef;
       }
 
       auto res = ::substOpaqueTypesWithUnderlyingTypesRec(
           substRef, substTy, inContext, contextExpansion, isContextWholeModule,
           *alreadySeen);
-      alreadySeen->erase(opaqueRoot->getDecl());
+      alreadySeen->erase(seenKey);
       return res;
     } else {
       // We're the top of the stack for the recursion check. Allocate a set of
       // opaque result type decls we've already seen for the rest of the check.
-      SmallPtrSet<OpaqueTypeDecl *, 8> seenDecls;
-      seenDecls.insert(opaqueRoot->getDecl());
+      llvm::DenseSet<SeenDecl> seenDecls;
+      seenDecls.insert(seenKey);
       return ::substOpaqueTypesWithUnderlyingTypesRec(
           substRef, substTy, inContext, contextExpansion, isContextWholeModule,
           seenDecls);

test/SILGen/opaque_type_repeat_application.swift

@@ -0,0 +1,21 @@
+// RUN: %target-swift-emit-sil -disable-availability-checking -verify %s
+
+// rdar://88120984
+
+protocol P {}
+
+private struct Wrapped<T: P>: P { var x: T }
+
+extension P {
+    func wrapped() -> some P {
+        return Wrapped(x: self)
+    }
+}
+
+class CWrap<T: P> { init(x: T) {} }
+
+func foo<T: P>(x: T) {
+    let y = x.wrapped().wrapped().wrapped().wrapped()
+
+    _ = CWrap(x: y)
+}