Merge pull request #1205 from robinkunde/improved_note

[Sema] improved binary op diagnostic notes for structs and payloaded enums

Author: lattner

include/swift/AST/DiagnosticsSema.def

@@ -243,6 +243,11 @@ NOTE(suggest_partial_overloads,none,
       "partially matching parameter lists|result types}0: %2",
       (bool, StringRef, StringRef))
 
+NOTE(no_binary_op_overload_for_enum_with_payload,none,
+      "binary operator '%0' cannot be synthesized for enums "
+      "with associated values",
+      (StringRef))
+
 ERROR(cannot_convert_initializer_value,none,
       "cannot convert value of type %0 to specified type %1", (Type,Type))
 ERROR(cannot_convert_initializer_value_protocol,none,

lib/Sema/CSDiag.cpp

@@ -3975,8 +3975,19 @@ bool FailureDiagnosis::visitApplyExpr(ApplyExpr *callExpr) {
       .highlight(lhsExpr->getSourceRange())
       .highlight(rhsExpr->getSourceRange());
     }
-    
-    calleeInfo.suggestPotentialOverloads(callExpr->getLoc());
+
+    if (lhsType->isEqual(rhsType) &&
+        isNameOfStandardComparisonOperator(overloadName) &&
+        lhsType->is<EnumType>() &&
+        !lhsType->getAs<EnumType>()->getDecl()
+          ->hasOnlyCasesWithoutAssociatedValues()) {
+      diagnose(callExpr->getLoc(),
+               diag::no_binary_op_overload_for_enum_with_payload,
+               overloadName);
+    } else {
+      calleeInfo.suggestPotentialOverloads(callExpr->getLoc());
+    }
+
     return true;
   }
 

test/Constraints/diagnostics.swift

@@ -718,4 +718,10 @@ func test17875634() {
   match.append(row, col)  // expected-error {{extra argument in call}}
 }
 
+// <https://github.com/apple/swift/pull/1205> Improved diagnostics for enums with associated values
+enum AssocTest {
+  case one(Int)
+}
 
+if AssocTest.one(1) == AssocTest.one(1) {} // expected-error{{binary operator '==' cannot be applied to two 'AssocTest' operands}}
+// expected-note @-1 {{binary operator '==' cannot be synthesized for enums with associated values}}