Require types to be contextually canonical in AbstractionPatterns.

Because violations of this might have made an AbstractionPattern incorrectly show up as abstract, it's possible that this will cause an ABI change.  However, I haven't been able to find any examples where it does, and certainly there's no way we can promise to maintain the old behavior, especially since it's not done consistently.

Author: rjmccall

include/swift/SIL/AbstractionPattern.h

@@ -323,8 +323,10 @@ class AbstractionPattern {
     TheKind = unsigned(kind);
     OrigType = origType;
     GenericSig = CanGenericSignature();
-    if (OrigType->hasTypeParameter())
+    if (OrigType->hasTypeParameter()) {
+      assert(OrigType == signature->getCanonicalTypeInContext(origType));
       GenericSig = signature;
+    }
   }
 
   void initClangType(CanGenericSignature signature,

lib/SIL/AbstractionPattern.cpp

@@ -46,12 +46,13 @@ TypeConverter::getAbstractionPattern(AbstractStorageDecl *decl,
 
 AbstractionPattern
 TypeConverter::getAbstractionPattern(SubscriptDecl *decl, bool isNonObjC) {
+  auto type = decl->getElementInterfaceType()->getCanonicalType();
   CanGenericSignature genericSig;
-  if (auto sig = decl->getGenericSignatureOfContext())
+  if (auto sig = decl->getGenericSignatureOfContext()) {
     genericSig = sig.getCanonicalSignature();
-  return AbstractionPattern(genericSig,
-                            decl->getElementInterfaceType()
-                                ->getCanonicalType());
+    type = sig->getCanonicalTypeInContext(type);
+  }
+  return AbstractionPattern(genericSig, type);
 }
 
 static const clang::Type *getClangType(const clang::Decl *decl) {
@@ -76,13 +77,15 @@ static Bridgeability getClangDeclBridgeability(const clang::Decl *decl) {
 
 AbstractionPattern
 TypeConverter::getAbstractionPattern(VarDecl *var, bool isNonObjC) {
-  CanGenericSignature genericSig;
-  if (auto sig = var->getDeclContext()->getGenericSignatureOfContext())
-    genericSig = sig.getCanonicalSignature();
-
   CanType swiftType = var->getInterfaceType()
                          ->getCanonicalType();
 
+  CanGenericSignature genericSig;
+  if (auto sig = var->getDeclContext()->getGenericSignatureOfContext()) {
+    genericSig = sig.getCanonicalSignature();
+    swiftType = genericSig->getCanonicalTypeInContext(swiftType);
+  }
+
   if (isNonObjC)
     return AbstractionPattern(genericSig, swiftType);
 
@@ -109,12 +112,15 @@ AbstractionPattern TypeConverter::getAbstractionPattern(EnumElementDecl *decl) {
          "Optional.Some does not have a unique abstraction pattern because "
          "optionals are re-abstracted");
 
+  CanType type = decl->getArgumentInterfaceType()->getCanonicalType();
+
   CanGenericSignature genericSig;
-  if (auto sig = decl->getParentEnum()->getGenericSignatureOfContext())
+  if (auto sig = decl->getParentEnum()->getGenericSignatureOfContext()) {
     genericSig = sig.getCanonicalSignature();
-  return AbstractionPattern(genericSig,
-                            decl->getArgumentInterfaceType()
-                                ->getCanonicalType());
+    type = genericSig->getCanonicalTypeInContext(type);
+  }
+
+  return AbstractionPattern(genericSig, type);
 }
 
 AbstractionPattern::EncodedForeignErrorInfo

lib/SIL/SILFunctionType.cpp

@@ -293,6 +293,8 @@ CanSILFunctionType SILFunctionType::getAutoDiffDerivativeFunctionType(
   // Given a type, returns its formal SIL parameter info.
   auto getTangentParameterInfoForOriginalResult =
       [&](CanType tanType, ResultConvention origResConv) -> SILParameterInfo {
+    if (derivativeFnGenSig)
+      tanType = derivativeFnGenSig->getCanonicalTypeInContext(tanType);
     AbstractionPattern pattern(derivativeFnGenSig, tanType);
     auto &tl =
         TC.getTypeLowering(pattern, tanType, TypeExpansionContext::minimal());
@@ -317,6 +319,8 @@ CanSILFunctionType SILFunctionType::getAutoDiffDerivativeFunctionType(
   // Given a type, returns its formal SIL result info.
   auto getTangentResultInfoForOriginalParameter =
       [&](CanType tanType, ParameterConvention origParamConv) -> SILResultInfo {
+    if (derivativeFnGenSig)
+      tanType = derivativeFnGenSig->getCanonicalTypeInContext(tanType);
     AbstractionPattern pattern(derivativeFnGenSig, tanType);
     auto &tl =
         TC.getTypeLowering(pattern, tanType, TypeExpansionContext::minimal());