[CSDiagnostic] Minor code improvement on MissingGenericArgumentsFailure addressing fixme

Author: LucianoPAlmeida

lib/Sema/CSDiagnostics.cpp

@@ -5271,14 +5271,10 @@ bool MissingGenericArgumentsFailure::diagnoseAsError() {
         scopedParameters[base].push_back(GP);
       });
 
-  // FIXME: this code should be generalized now that we can anchor the
-  // fixes on the TypeRepr with the missing generic arg.
   if (!isScoped) {
-    assert(getAnchor().is<Expr *>() || getAnchor().is<TypeRepr *>());
-    if (auto *expr = getAsExpr(getAnchor()))
-      return diagnoseForAnchor(expr, Parameters);
-
-    return diagnoseForAnchor(getAnchor().get<TypeRepr *>(), Parameters);
+    auto anchor = getAnchor();
+    assert(anchor.is<Expr *>() || anchor.is<TypeRepr *>());
+    return diagnoseForAnchor(anchor, Parameters);
   }
 
   bool diagnosed = false;
@@ -5288,7 +5284,7 @@ bool MissingGenericArgumentsFailure::diagnoseAsError() {
 }
 
 bool MissingGenericArgumentsFailure::diagnoseForAnchor(
-    Anchor anchor, ArrayRef<GenericTypeParamType *> params) const {
+    ASTNode anchor, ArrayRef<GenericTypeParamType *> params) const {
   bool diagnosed = false;
   for (auto *GP : params)
     diagnosed |= diagnoseParameter(anchor, GP);
@@ -5322,11 +5318,9 @@ bool MissingGenericArgumentsFailure::diagnoseForAnchor(
 }
 
 bool MissingGenericArgumentsFailure::diagnoseParameter(
-    Anchor anchor, GenericTypeParamType *GP) const {
+    ASTNode anchor, GenericTypeParamType *GP) const {
   auto &solution = getSolution();
-
-  auto loc = anchor.is<Expr *>() ? anchor.get<Expr *>()->getLoc()
-                                 : anchor.get<TypeRepr *>()->getLoc();
+  auto loc = ::getLoc(anchor);
 
   auto *locator = getLocator();
   // Type variables associated with missing generic parameters are
@@ -5372,7 +5366,7 @@ bool MissingGenericArgumentsFailure::diagnoseParameter(
 }
 
 void MissingGenericArgumentsFailure::emitGenericSignatureNote(
-    Anchor anchor) const {
+    ASTNode anchor) const {
   auto &solution = getSolution();
   auto *paramDC = getDeclContext();
 

lib/Sema/CSDiagnostics.h

@@ -1698,8 +1698,6 @@ class InOutConversionFailure final : public ContextualFailure {
 /// _ = S()
 /// ```
 class MissingGenericArgumentsFailure final : public FailureDiagnostic {
-  using Anchor = llvm::PointerUnion<TypeRepr *, Expr *>;
-
   SmallVector<GenericTypeParamType *, 4> Parameters;
 
 public:
@@ -1722,13 +1720,13 @@ class MissingGenericArgumentsFailure final : public FailureDiagnostic {
 
   bool diagnoseAsError() override;
 
-  bool diagnoseForAnchor(Anchor anchor,
+  bool diagnoseForAnchor(ASTNode anchor,
                          ArrayRef<GenericTypeParamType *> params) const;
 
-  bool diagnoseParameter(Anchor anchor, GenericTypeParamType *GP) const;
+  bool diagnoseParameter(ASTNode anchor, GenericTypeParamType *GP) const;
 
 private:
-  void emitGenericSignatureNote(Anchor anchor) const;
+  void emitGenericSignatureNote(ASTNode anchor) const;
 
   /// Retrieve representative locations for associated generic prameters.
   ///