[CSDiagnostics] Tailor diagnostic for define missing member when involving a collectin type

Author: LucianoPAlmeida

lib/Sema/CSDiagnostics.cpp

@@ -3213,7 +3213,7 @@ bool MissingMemberFailure::diagnoseAsError() {
   if (diagnoseForDynamicCallable())
     return true;
 
-  if (diagnoseForDefaultAnyArrayLiteral())
+  if (diagnoseInLiteralCollectionContext())
     return true;
 
   auto baseType = resolveType(getBaseType())->getWithoutSpecifierType();
@@ -3402,23 +3402,30 @@ bool MissingMemberFailure::diagnoseForDynamicCallable() const {
   return false;
 }
 
-bool MissingMemberFailure::diagnoseForDefaultAnyArrayLiteral() const {
+bool MissingMemberFailure::diagnoseInLiteralCollectionContext() const {
   auto &cs = getConstraintSystem();
-  auto *expr = getAsExpr(getAnchor());
+  auto *expr = castToExpr(getAnchor());
   auto *parentExpr = cs.getParentExpr(expr);
-  auto contextualType = getContextualType(parentExpr);
-  auto baseType = resolveType(getBaseType())->getWithoutSpecifierType();
+  auto &solution = getSolution();
 
-  if (contextualType)
+  if (!(parentExpr && isa<UnresolvedMemberExpr>(expr)))
     return false;
-  
-  if (isa<UnresolvedMemberExpr>(expr) &&
-      parentExpr && isa<ArrayExpr>(parentExpr)) {
-    if (auto *metatype = baseType->getAs<MetatypeType>()) {
-      baseType = metatype->getInstanceType();
-    }
-    
-    if (baseType->isAny()) {
+
+  auto parentType = getType(parentExpr);
+
+  if (!cs.isCollectionType(parentType) && !parentType->is<TupleType>())
+    return false;
+
+  if (isa<TupleExpr>(parentExpr)) {
+    parentExpr = cs.getParentExpr(parentExpr);
+    if (!parentExpr)
+      return false;
+  }
+
+  if (auto *defaultableVar =
+          cs.getType(parentExpr)->getAs<TypeVariableType>()) {
+    if (solution.DefaultedConstraints.count(
+            defaultableVar->getImpl().getLocator()) != 0) {
       emitDiagnostic(diag::unresolved_member_no_inference, getName());
       return true;
     }

lib/Sema/CSDiagnostics.h

@@ -1060,9 +1060,9 @@ class MissingMemberFailure final : public InvalidMemberRefFailure {
   /// defines only `dynamicallyCall(withArguments:)` variant.
   bool diagnoseForDynamicCallable() const;
 
-  /// Tailored diagnostics for array literal with unresolved member expression
-  /// that defaults the element to element type. e.g. _ = [.e]
-  bool diagnoseForDefaultAnyArrayLiteral() const;
+  /// Tailored diagnostics for collection literal with unresolved member expression
+  /// that defaults the element type. e.g. _ = [.e]
+  bool diagnoseInLiteralCollectionContext() const;
 
   static DeclName findCorrectEnumCaseName(Type Ty,
                                           TypoCorrectionResults &corrections,

test/Constraints/members.swift

@@ -668,3 +668,8 @@ func test_34770265(_ dict: [Int: Int]) {
 // SR-12672
 _ = [.e] // expected-error {{reference to member 'e' cannot be resolved without a contextual type}}
 let _ : [Any] = [.e] // expected-error {{type 'Any' has no member 'e'}}
+_ = [1 :.e] // expected-error {{reference to member 'e' cannot be resolved without a contextual type}}
+_ = [.e: 1] // expected-error {{reference to member 'e' cannot be resolved without a contextual type}}
+let _ : [Int: Any] = [1 : .e] // expected-error {{type 'Any' has no member 'e'}}
+let _ : (Int, Any) = (1, .e) // expected-error {{type 'Any' has no member 'e'}}
+_ = (1, .e) // expected-error {{cannot infer contextual base in reference to member 'e'}}