Sema: Change the diagnostic to choices made by the constraint system

Author: sl

lib/Sema/CSDiagnostics.cpp

@@ -101,6 +101,35 @@ Expr *FailureDiagnostic::getArgumentExprFor(Expr *anchor) const {
   return nullptr;
 }
 
+// TODO: Replace duplications of this logic with calls to this.
+Optional<SelectedOverload> FailureDiagnostic::getChoiceFor(Expr *expr) {
+  auto &cs = getConstraintSystem();
+  ConstraintLocator *locator = nullptr;
+
+  if (auto *call = dyn_cast<CallExpr>(expr)) {
+    auto *fnExpr = call->getFn();
+    return getChoiceFor(fnExpr);
+  } else if (auto *UDE = dyn_cast<UnresolvedDotExpr>(expr)) {
+    locator = cs.getConstraintLocator(UDE, ConstraintLocator::Member);
+  } else if (auto *UME = dyn_cast<UnresolvedMemberExpr>(expr)) {
+    locator = cs.getConstraintLocator(UME, ConstraintLocator::UnresolvedMember);
+  } else if (auto *TE = dyn_cast<TypeExpr>(expr)) {
+    locator = cs.getConstraintLocator(call,
+                                      {ConstraintLocator::ApplyFunction,
+                                        ConstraintLocator::ConstructorMember},
+                                      /*summaryFlags=*/0);
+  } else if (auto *SE = dyn_cast<SubscriptExpr>(expr)) {
+    locator = cs.getConstraintLocator(SE, ConstraintLocator::SubscriptMember);
+  } else {
+    locator = cs.getConstraintLocator(expr);
+  }
+  
+  if(!locator)
+    return None;
+
+  return getOverloadChoiceIfAvailable(locator);
+}
+
 Type RequirementFailure::getOwnerType() const {
   return getType(getRawAnchor())
       ->getInOutObjectType()
@@ -2042,42 +2071,43 @@ bool AllowTypeOrInstanceMemberFailure::diagnoseAsError() {
         emitDiagnostic(loc, diag::super_initializer_not_in_initializer);
         return true;
       }
+      
+      auto isInsideCall = [this](Expr *expr) {
+        auto &cs = getConstraintSystem();
+        auto argExpr = cs.getParentExpr(expr);
+        if (!argExpr)
+          return false;
+        auto possibleCallExpr = cs.getParentExpr(expr);
+        return possibleCallExpr && isa<CallExpr>(possibleCallExpr);
+      };
+
+      auto *initCall = cs.getParentExpr(cs.getParentExpr(ctorRef));
+
+      auto isImmutable = [&DC](ValueDecl *decl) {
+        if (auto *storage = dyn_cast<AbstractStorageDecl>(decl))
+          return !storage->isSettable(DC) ||
+                !storage->isSetterAccessibleFrom(DC);
 
-      // Dig through the chain of member accesses until we find the last
-      // UnresolvedDotExpr.
-      auto *lastUnresolved = ctorRef;
-      while (auto *nextMember =
-                 dyn_cast_or_null<UnresolvedDotExpr>(lastUnresolved->getBase()))
-        lastUnresolved = nextMember;
-
-      if (auto *DRE = dyn_cast<DeclRefExpr>(lastUnresolved->getBase())) {
-        auto isInsideCall = [this](Expr *expr) {
-          auto &cs = getConstraintSystem();
-          auto argExpr = cs.getParentExpr(expr);
-          if (!argExpr)
-            return false;
-          auto possibleCallExpr = cs.getParentExpr(expr);
-          return possibleCallExpr && isa<CallExpr>(possibleCallExpr);
-        };
-
-        auto *initCall = cs.getParentExpr(cs.getParentExpr(ctorRef));
-
-        // We can only check if the base is settable here so provide the
-        // assignment diagnostic as it's our best guess.
-        if (DRE->getDecl()->isSettable(DC, DRE) && !isInsideCall(initCall) &&
+        return false;
+      };
+      
+      auto selection = getChoiceFor(ctorRef->getBase());
+      if (selection) {
+        OverloadChoice choice = selection.getValue().choice;
+        if (choice.isDecl() && !isImmutable(choice.getDecl()) && !isInsideCall(initCall) &&
             cs.getContextualTypePurpose() == CTP_Unused) {
           auto fixItLoc = ctorRef->getBase()->getSourceRange().End;
           emitDiagnostic(loc, diag::init_not_instance_member_use_assignment)
               .fixItInsertAfter(fixItLoc, " = ");
           return true;
         }
-      }
 
-      SourceRange fixItRng = ctorRef->getNameLoc().getSourceRange();
-      emitDiagnostic(loc, diag::init_not_instance_member)
-          .fixItInsert(fixItRng.Start, "type(of: ")
-          .fixItInsertAfter(fixItRng.End, ")");
-      return true;
+        SourceRange fixItRng = ctorRef->getNameLoc().getSourceRange();
+        emitDiagnostic(loc, diag::init_not_instance_member)
+            .fixItInsert(fixItRng.Start, "type(of: ")
+            .fixItInsertAfter(fixItRng.End, ")");
+        return true;
+      }
     }
   }
 

lib/Sema/CSDiagnostics.h

@@ -154,6 +154,8 @@ class FailureDiagnostic {
   /// \returns An argument expression if given anchor is a call, member
   /// reference or subscript, nullptr otherwise.
   Expr *getArgumentExprFor(Expr *anchor) const;
+  
+  Optional<SelectedOverload> getChoiceFor(Expr *);
 
 private:
   /// Compute anchor expression associated with current diagnostic.