Sema: Compute captures correctly for closures without source locations

Soon we'll be synthesizing more implicit autoclosures in CSApply, and
this case comes up.

Author: slavapestov

lib/Sema/TypeCheckCaptures.cpp

@@ -42,7 +42,8 @@ class FindCapturedVars : public ASTWalker {
   OpaqueValueExpr *OpaqueValue = nullptr;
   SourceLoc CaptureLoc;
   DeclContext *CurDC;
-  bool NoEscape, ObjC, IsGenericFunction;
+  bool NoEscape, ObjC;
+  bool HasGenericParamCaptures;
 
 public:
   FindCapturedVars(SourceLoc CaptureLoc,
@@ -51,23 +52,23 @@ class FindCapturedVars : public ASTWalker {
                    bool ObjC,
                    bool IsGenericFunction)
       : Context(CurDC->getASTContext()), CaptureLoc(CaptureLoc), CurDC(CurDC),
-        NoEscape(NoEscape), ObjC(ObjC), IsGenericFunction(IsGenericFunction) {}
+        NoEscape(NoEscape), ObjC(ObjC), HasGenericParamCaptures(IsGenericFunction) {}
 
   CaptureInfo getCaptureInfo() const {
     DynamicSelfType *dynamicSelfToRecord = nullptr;
-    bool hasGenericParamCaptures = IsGenericFunction;
 
     // Only local functions capture dynamic 'Self'.
     if (CurDC->getParent()->isLocalContext()) {
-      if (GenericParamCaptureLoc.isValid())
-        hasGenericParamCaptures = true;
-
       if (DynamicSelfCaptureLoc.isValid())
         dynamicSelfToRecord = DynamicSelf;
     }
 
     return CaptureInfo(Context, Captures, dynamicSelfToRecord, OpaqueValue,
-                       hasGenericParamCaptures);
+                       HasGenericParamCaptures);
+  }
+
+  bool hasGenericParamCaptures() const {
+    return HasGenericParamCaptures;
   }
 
   SourceLoc getGenericParamCaptureLoc() const {
@@ -148,17 +149,19 @@ class FindCapturedVars : public ASTWalker {
         if ((t->is<ArchetypeType>() ||
              t->is<GenericTypeParamType>()) &&
             !t->isOpenedExistential() &&
-            GenericParamCaptureLoc.isInvalid()) {
+            !HasGenericParamCaptures) {
           GenericParamCaptureLoc = loc;
+          HasGenericParamCaptures = true;
         }
       }));
     }
 
     if (auto *gft = type->getAs<GenericFunctionType>()) {
       TypeCaptureWalker walker(ObjC, [&](Type t) {
         if (t->is<GenericTypeParamType>() &&
-            GenericParamCaptureLoc.isInvalid()) {
+            !HasGenericParamCaptures) {
           GenericParamCaptureLoc = loc;
+          HasGenericParamCaptures = true;
         }
       });
 
@@ -339,9 +342,12 @@ class FindCapturedVars : public ASTWalker {
       addCapture(CapturedValue(capture.getDecl(), Flags, capture.getLoc()));
     }
 
-    if (GenericParamCaptureLoc.isInvalid())
-      if (captureInfo.hasGenericParamCaptures())
+    if (!HasGenericParamCaptures) {
+      if (captureInfo.hasGenericParamCaptures()) {
         GenericParamCaptureLoc = loc;
+        HasGenericParamCaptures = true;
+      }
+    }
 
     if (DynamicSelfCaptureLoc.isInvalid()) {
       if (captureInfo.hasDynamicSelfCapture()) {
@@ -631,7 +637,7 @@ void TypeChecker::computeCaptures(AnyFunctionRef AFR) {
 
   // Extensions of generic ObjC functions can't use generic parameters from
   // their context.
-  if (AFD && finder.getGenericParamCaptureLoc().isValid()) {
+  if (AFD && finder.hasGenericParamCaptures()) {
     if (auto Clas = AFD->getParent()->getSelfClassDecl()) {
       if (Clas->usesObjCGenericsModel()) {
         AFD->diagnose(diag::objc_generic_extension_using_type_parameter);