Merge pull request #13622 from ahoppen/unused-result-implicit-funcs

Author: swift-ci

lib/Sema/TypeCheckStmt.cpp

@@ -1201,6 +1201,18 @@ void TypeChecker::checkIgnoredExpr(Expr *E) {
 
     // Otherwise, produce a generic diagnostic.
     if (callee) {
+      auto &ctx = callee->getASTContext();
+      if (callee->isImplicit()) {
+        // Translate calls to implicit functions to their user-facing names
+        if (callee->getBaseName() == ctx.Id_derived_enum_equals ||
+            callee->getBaseName() == ctx.Id_derived_struct_equals) {
+          diagnose(fn->getLoc(), diag::expression_unused_result_operator,
+                   ctx.Id_EqualsOperator)
+            .highlight(SR1).highlight(SR2);
+          return;
+        }
+      }
+
       auto diagID = diag::expression_unused_result_call;
       if (callee->getFullName().isOperator())
         diagID = diag::expression_unused_result_operator;

test/Sema/enum_equatable_hashable.swift

@@ -9,6 +9,8 @@ enum Foo {
 if Foo.A == .B { }
 var aHash: Int = Foo.A.hashValue
 
+Foo.A == Foo.B // expected-warning {{result of operator '==' is unused}}
+
 enum Generic<T> {
   case A, B
 

test/Sema/struct_equatable_hashable.swift

@@ -10,6 +10,8 @@ struct Point: Hashable {
 if Point(x: 1, y: 2) == Point(x: 2, y: 1) { }
 var pointHash: Int = Point(x: 3, y: 5).hashValue
 
+Point(x: 1, y: 2) == Point(x: 2, y: 1) // expected-warning {{result of operator '==' is unused}}
+
 struct Pair<T: Hashable>: Hashable {
   let first: T
   let second: T