[Sema] Adjustments on implementation and diagnostic message for SR-14720

Author: LucianoPAlmeida

include/swift/AST/DiagnosticsSema.def

@@ -3890,10 +3890,9 @@ ERROR(converting_noattrfunc_to_type,none,
       "converting %select{non-escaping|non-concurrent function}0 value to %1 "
       "may %select{allow it to escape|introduce data races}0",
       (unsigned, Type))
-ERROR(converting_noattrfunc_contravariant_parameter_position,none,
-      "converting escaping to non-escaping functions of type %2 in parameter position "
-      "#%0 of function type %3 %1 is not allowed",
-      (unsigned, Identifier, Type, DescriptiveDeclKind))
+NOTE(escape_expected_at_parameter_position,none,
+     "parameter #%0 expects escaping value of type %1",
+     (unsigned, Type))
 NOTE(add_explicit_escaping,none,
      "add explicit @escaping to function parameter #%0",
      (unsigned))

lib/Sema/CSDiagnostics.cpp

@@ -932,26 +932,27 @@ bool AttributedFuncToTypeConversionFailure::
   if (!loc->findLast<LocatorPathElt::FunctionArgument>())
     return false;
 
-  auto &solution = getSolution();
-  auto decl = getDestinationVarDecl(AE, solution);
-  if (!decl)
-    return false;
+  auto destType = getType(AE->getDest())->lookThroughAllOptionalTypes();
+  auto destFnType = destType->castTo<FunctionType>();
+  auto sourceType = getType(AE->getSrc())->lookThroughAllOptionalTypes();
 
   // The tuple locator element will give us the exact parameter mismatch
   // position.
   auto tupleElt = loc->getLastElementAs<LocatorPathElt::TupleElement>();
   auto mismatchPosition = tupleElt ? tupleElt->getIndex() : 0;
+  auto param = destFnType->getParams()[mismatchPosition];
 
-  auto destInterfaceType =
-      decl->getInterfaceType()->lookThroughAllOptionalTypes();
-  auto destInterfaceFnType = destInterfaceType->castTo<FunctionType>();
-  auto param = destInterfaceFnType->getParams()[mismatchPosition];
-  emitDiagnostic(diag::converting_noattrfunc_contravariant_parameter_position,
-                 mismatchPosition, decl->getName(), param.getParameterType(),
-                 decl->getDescriptiveKind());
+  emitDiagnostic(diag::cannot_convert_assign, sourceType, destType);
+  emitDiagnosticAt(AE->getDest()->getLoc(),
+                   diag::escape_expected_at_parameter_position,
+                   mismatchPosition, param.getParameterType());
 
-  auto note = emitDiagnosticAt(decl->getLoc(), diag::add_explicit_escaping,
-                               mismatchPosition);
+  auto &solution = getSolution();
+  auto decl = getDestinationVarDecl(AE, solution);
+  // We couldn't find a declaration to add an extra note with a fix-it but
+  // the main diagnostic was already covered.
+  if (!decl)
+    return true;
 
   auto declRepr = decl->getTypeReprOrParentPatternTypeRepr();
   class TopLevelFuncReprFinder : public ASTWalker {
@@ -972,8 +973,10 @@ bool AttributedFuncToTypeConversionFailure::
 
   auto declFnRepr = fnFinder.FnRepr;
   if (!declFnRepr)
-    return false;
+    return true;
 
+  auto note = emitDiagnosticAt(decl->getLoc(), diag::add_explicit_escaping,
+                               mismatchPosition);
   auto argsRepr = declFnRepr->getArgsTypeRepr();
   auto argRepr = argsRepr->getElement(mismatchPosition).Type;
   if (!param.isAutoClosure()) {

test/Constraints/function_conversion.swift

@@ -59,7 +59,8 @@ takesAny(consumeEscaping)
 
 var noEscapeParam: ((Int) -> Int) -> () = consumeNoEscape // expected-note {{add explicit @escaping to function parameter}}{{21-21=@escaping }}
 var escapingParam: (@escaping (Int) -> Int) -> () = consumeEscaping
-noEscapeParam = escapingParam // expected-error {{converting escaping to non-escaping functions of type '(Int) -> Int' in parameter position #0 of function type var 'noEscapeParam' is not allowed}}
+noEscapeParam = escapingParam // expected-error {{cannot assign value of type '(@escaping (Int) -> Int) -> ()' to type '((Int) -> Int) -> ()'}}
+// expected-note@-1{{parameter #0 expects escaping value of type '(Int) -> Int'}}
 
 escapingParam = takesAny
 noEscapeParam = takesAny // expected-error {{converting non-escaping value to 'Any' may allow it to escape}}

test/attr/attr_escaping.swift

@@ -153,7 +153,8 @@ class FooClass {
   }
   var computedEscaping : (@escaping ()->Int)->Void {
     get { return stored! }
-    set(newValue) { stored = newValue } // expected-error{{converting escaping to non-escaping functions of type '() -> Int' in parameter position #0 of function type property 'stored' is not allowed}}
+    set(newValue) { stored = newValue } // expected-error{{cannot assign value of type '(@escaping () -> Int) -> Void' to type '(() -> Int) -> Void'}}
+    // expected-note@-1{{parameter #0 expects escaping value of type '() -> Int'}}
   }
 }
 
@@ -241,23 +242,28 @@ class SR14720 {
   let callbackOpt: ((() -> Void) -> Void)? // expected-note{{add explicit @escaping to function parameter #0}} {{22-22=@escaping }}
 
   init(f: @escaping (@escaping() -> Void) -> Void) {
-    self.callback = f // expected-error{{converting escaping to non-escaping functions of type '() -> Void' in parameter position #0 of function type property 'callback' is not allowed}}
+    self.callback = f // expected-error{{cannot assign value of type '(@escaping () -> Void) -> Void' to type '(() -> Void) -> Void'}}
+    // expected-note@-1{{parameter #0 expects escaping value of type '() -> Void'}}
     self.ok = f // Ok
   }
 
   init(af: @escaping (@escaping() -> Void) -> Void) {
-    self.callbackOpt = af // expected-error{{converting escaping to non-escaping functions of type '() -> Void' in parameter position #0 of function type property 'callbackOpt' is not allowed}}
+    self.callbackOpt = af // expected-error{{cannot assign value of type '(@escaping () -> Void) -> Void' to type '(() -> Void) -> Void'}}
+    // expected-note@-1{{parameter #0 expects escaping value of type '() -> Void'}}  
   }
 
   init(ag: @escaping (@escaping() -> Void) -> Void) {
-    global = ag // expected-error{{converting escaping to non-escaping functions of type '() -> Void' in parameter position #0 of function type var 'global' is not allowed}}
+    global = ag // expected-error{{cannot assign value of type '(@escaping () -> Void) -> Void' to type '(() -> Void) -> Void'}}
+    // expected-note@-1{{parameter #0 expects escaping value of type '() -> Void'}}
   }
 
   init(a: @escaping (@escaping () -> Void) -> Void) {
-    self.callbackAuto = a // expected-error{{converting escaping to non-escaping functions of type '() -> Void' in parameter position #0 of function type property 'callbackAuto' is not allowed}}
+    self.callbackAuto = a // expected-error{{cannot assign value of type '(@escaping () -> Void) -> Void' to type '(@autoclosure () -> Void) -> Void'}}
+    // expected-note@-1{{parameter #0 expects escaping value of type '() -> Void'}}
   }
 
   init(f: @escaping (() -> Void, @escaping() -> Void) -> Void) {
-    self.callback1 = f // expected-error{{converting escaping to non-escaping functions of type '() -> Void' in parameter position #1 of function type property 'callback1' is not allowed}}
+    self.callback1 = f // expected-error{{cannot assign value of type '(() -> Void, @escaping () -> Void) -> Void' to type '(() -> Void, () -> Void) -> Void'}}
+    // expected-note@-1{{parameter #1 expects escaping value of type '() -> Void'}}
   }
 }