Merge pull request #26543 from xedin/diag-arr-to-ptr-elt-conv-failures

[Diagnostics] Extend generic argument mismatch to cover [T] to Unsafe…

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -611,7 +611,15 @@ Optional<Diag<Type, Type>> GenericArgumentsMismatchFailure::getDiagnosticFor(
 }
 
 void GenericArgumentsMismatchFailure::emitNoteForMismatch(int position) {
-  auto genericTypeDecl = getActual()->getCanonicalType()->getAnyGeneric();
+  auto *locator = getLocator();
+  // Since there could be implicit conversions assoicated with argument
+  // to parameter conversions, let's use parameter type as a source of
+  // generic parameter information.
+  auto paramSourceTy =
+      locator->isLastElement(ConstraintLocator::ApplyArgToParam) ? getRequired()
+                                                                 : getActual();
+
+  auto genericTypeDecl = paramSourceTy->getAnyGeneric();
   auto param = genericTypeDecl->getGenericParams()->getParams()[position];
 
   auto lhs = resolveType(getActual()->getGenericArgs()[position])

lib/Sema/CSSimplify.cpp

@@ -6624,11 +6624,24 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
     auto baseType2 = getBaseTypeForPointer(*this, t2);
 
     increaseScore(ScoreKind::SK_ValueToPointerConversion);
-    return matchTypes(baseType1, baseType2,
-                      ConstraintKind::BindToPointerType,
-                      subflags, locator);
+    auto result = matchTypes(baseType1, baseType2,
+                             ConstraintKind::BindToPointerType,
+                             subflags, locator);
+
+    if (!(result.isFailure() && shouldAttemptFixes()))
+      return result;
+
+    auto *arrTy = obj1->getAs<BoundGenericType>();
+    // Let's dig out underlying pointer type since it could
+    // be wrapped into N (implicit) optionals.
+    auto *ptrTy =
+        type2->lookThroughAllOptionalTypes()->getAs<BoundGenericType>();
+
+    auto *fix = GenericArgumentsMismatch::create(*this, arrTy, ptrTy, {0},
+                                                 getConstraintLocator(locator));
+    return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
   }
-      
+
   // String ===> UnsafePointer<[U]Int8>
   case ConversionRestrictionKind::StringToPointer: {
     addContextualScore();

test/Parse/pointer_conversion.swift.gyb

@@ -54,7 +54,8 @@ func mutablePointerArguments(_ p: UnsafeMutablePointer<Int>,
   var ii: [Int] = [0, 1, 2]
   var ff: [Float] = [0, 1, 2]
   takesMutablePointer(&ii)
-  takesMutablePointer(&ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'Int'}}
+  takesMutablePointer(&ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'UnsafeMutablePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Float' and 'Int') are expected to be equal}}
   takesMutablePointer(ii) // expected-error{{cannot convert value of type '[Int]' to expected argument type 'UnsafeMutablePointer<Int>${diag_suffix}'}}
   takesMutablePointer(ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'UnsafeMutablePointer<Int>${diag_suffix}'}}
 
@@ -152,9 +153,11 @@ func constPointerArguments(_ p: UnsafeMutablePointer<Int>,
   var ii: [Int] = [0, 1, 2]
   var ff: [Float] = [0, 1, 2]
   takesConstPointer(&ii)
-  takesConstPointer(&ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'Int'}}
+  takesConstPointer(&ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'UnsafePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Float' and 'Int') are expected to be equal}}
   takesConstPointer(ii)
-  takesConstPointer(ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'UnsafePointer<Int>${diag_suffix}'}}
+  takesConstPointer(ff) // expected-error{{cannot convert value of type '[Float]' to expected argument type 'UnsafePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Float' and 'Int') are expected to be equal}}
   takesConstPointer([0, 1, 2])
   // <rdar://problem/22308330> QoI: CSDiags doesn't handle array -> pointer impl conversions well
   takesConstPointer([0.0, 1.0, 2.0])
@@ -338,7 +341,8 @@ func f23202128() {
   UMP(&pipe)  // expected-error {{cannot pass immutable value as inout argument: 'pipe' is a 'let' constant}}
 
   var pipe2: [Int] = [0, 0]
-  UMP(&pipe2) // expected-error {{cannot convert value of type '[Int]' to expected argument type 'Int32'}}
+  UMP(&pipe2) // expected-error {{cannot convert value of type '[Int]' to expected argument type 'UnsafeMutablePointer<Int32>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and 'Int32') are expected to be equal}}
 
 
   UP(pipe)    // ok