[ConstraintSystem] Extend generic argument mismatch fix to all pointer conversions

This makes it possible to diagnose all implicit pointer
conversions in argument positions with a better error
message which preserves enclosing types, and allows to
share base type matching logic across all pointer conversions.

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -2558,8 +2558,15 @@ bool ConstraintSystem::repairFailures(
     // `&`.
     if (lhs->is<LValueType>() &&
         (rhs->is<InOutType>() || rhs->getAnyPointerElementType())) {
-      auto result = matchTypes(InOutType::get(lhs->getRValueType()), rhs,
-                               ConstraintKind::ArgumentConversion,
+      auto baseType = rhs->is<InOutType>() ? rhs->getInOutObjectType()
+                                           : rhs->getAnyPointerElementType();
+
+      // Let's use `BindToPointer` constraint here to match up base types
+      // of implied `inout` argument and `inout` or pointer parameter.
+      // This helps us to avoid implicit conversions associated with
+      // `ArgumentConversion` constraint.
+      auto result = matchTypes(lhs->getRValueType(), baseType,
+                               ConstraintKind::BindToPointerType,
                                TypeMatchFlags::TMF_ApplyingFix, locator);
 
       if (result.isSuccess()) {
@@ -6958,6 +6965,44 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
 
   TypeMatchOptions subflags = getDefaultDecompositionOptions(flags);
 
+  auto matchPointerBaseTypes = [&](Type baseType1,
+                                   Type baseType2) -> SolutionKind {
+    if (restriction != ConversionRestrictionKind::PointerToPointer)
+      increaseScore(ScoreKind::SK_ValueToPointerConversion);
+
+    auto result =
+        matchTypes(baseType1, baseType2, ConstraintKind::BindToPointerType,
+                   subflags, locator);
+
+    if (!(result.isFailure() && shouldAttemptFixes()))
+      return result;
+
+    BoundGenericType *ptr1 = nullptr;
+    BoundGenericType *ptr2 = nullptr;
+
+    switch (restriction) {
+    case ConversionRestrictionKind::ArrayToPointer:
+    case ConversionRestrictionKind::InoutToPointer: {
+      ptr2 = type2->lookThroughAllOptionalTypes()->castTo<BoundGenericType>();
+      ptr1 = BoundGenericType::get(ptr2->getDecl(), ptr2->getParent(),
+                                   {baseType1});
+      break;
+    }
+
+    case ConversionRestrictionKind::PointerToPointer:
+      ptr1 = type1->castTo<BoundGenericType>();
+      ptr2 = type2->castTo<BoundGenericType>();
+      break;
+
+    default:
+      return SolutionKind::Error;
+    }
+
+    auto *fix = GenericArgumentsMismatch::create(*this, ptr1, ptr2, {0},
+                                                 getConstraintLocator(locator));
+    return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
+  };
+
   switch (restriction) {
   // for $< in { <, <c, <oc }:
   //   T_i $< U_i ===> (T_i...) $< (U_i...)
@@ -7077,23 +7122,7 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
     auto baseType1 = getFixedTypeRecursive(*isArrayType(obj1), false);
     auto baseType2 = getBaseTypeForPointer(*this, t2);
 
-    increaseScore(ScoreKind::SK_ValueToPointerConversion);
-    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;
+    return matchPointerBaseTypes(baseType1, baseType2);
   }
 
   // String ===> UnsafePointer<[U]Int8>
@@ -7146,13 +7175,8 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
 
     auto baseType1 = type1->getInOutObjectType();
     auto baseType2 = getBaseTypeForPointer(*this, t2);
-    
-    // Set up the disjunction for the array or scalar cases.
 
-    increaseScore(ScoreKind::SK_ValueToPointerConversion);
-    return matchTypes(baseType1, baseType2,
-                      ConstraintKind::BindToPointerType,
-                      subflags, locator);
+    return matchPointerBaseTypes(baseType1, baseType2);
   }
 
   // T <p U ===> UnsafeMutablePointer<T> <a UnsafeMutablePointer<U>
@@ -7162,10 +7186,8 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
 
     Type baseType1 = getBaseTypeForPointer(*this, t1);
     Type baseType2 = getBaseTypeForPointer(*this, t2);
-    
-    return matchTypes(baseType1, baseType2,
-                      ConstraintKind::BindToPointerType,
-                      subflags, locator);
+
+    return matchPointerBaseTypes(baseType1, baseType2);
   }
 
   // T < U or T is bridged to V where V < U ===> Array<T> <c Array<U>

test/ClangImporter/objc_id_as_any.swift

@@ -17,10 +17,12 @@ idLover.takesId(ArbitraryThing())
 var x: AnyObject = NSObject()
 idLover.takesArray(ofId: &x)
 var xAsAny = x as Any
-idLover.takesArray(ofId: &xAsAny)  // expected-error{{argument type 'Any' does not conform to expected type 'AnyObject'}}
+idLover.takesArray(ofId: &xAsAny)  // expected-error{{cannot convert value of type 'UnsafePointer<Any>' to expected argument type 'UnsafePointer<AnyObject>'}}
+// expected-note@-1 {{arguments to generic parameter 'Pointee' ('Any' and 'AnyObject') are expected to be equal}}
 
 var y: Any = NSObject()
-idLover.takesArray(ofId: &y) // expected-error{{argument type 'Any' does not conform to expected type 'AnyObject'}}
+idLover.takesArray(ofId: &y) // expected-error{{cannot convert value of type 'UnsafePointer<Any>' to expected argument type 'UnsafePointer<AnyObject>'}}
+// expected-note@-1 {{arguments to generic parameter 'Pointee' ('Any' and 'AnyObject') are expected to be equal}}
 
 idLover.takesId(x)
 idLover.takesId(y)

test/Parse/pointer_conversion.swift.gyb

@@ -48,18 +48,20 @@ func mutablePointerArguments(_ p: UnsafeMutablePointer<Int>,
   var i: Int = 0
   var f: Float = 0
   takesMutablePointer(&i)
-  takesMutablePointer(&f) // expected-error{{cannot convert value of type 'Float' to expected argument type 'Int'}}
+  takesMutablePointer(&f) // expected-error{{cannot convert value of type 'UnsafeMutablePointer<Float>' to expected argument type 'UnsafeMutablePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Float' and 'Int') are expected to be equal}}
   takesMutablePointer(i) // expected-error{{cannot convert value of type 'Int' to expected argument type 'UnsafeMutablePointer<Int>${diag_suffix}'}}
   takesMutablePointer(f) // expected-error{{cannot convert value of type 'Float' to expected argument type 'UnsafeMutablePointer<Int>${diag_suffix}'}}
   var ii: [Int] = [0, 1, 2]
   var ff: [Float] = [0, 1, 2]
   takesMutablePointer(&ii)
-  takesMutablePointer(&ff) // expected-error{{cannot convert value of type 'Array<Float>' to expected argument type 'UnsafeMutablePointer<Int>'}}
+  takesMutablePointer(&ff) // expected-error{{cannot convert value of type 'UnsafeMutablePointer<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}'}}
 
-  takesMutableArrayPointer(&i) // expected-error{{cannot convert value of type 'Int' to expected argument type '[Int]'}}
+  takesMutableArrayPointer(&i) // expected-error{{cannot convert value of type 'UnsafeMutablePointer<Int>' to expected argument type 'UnsafeMutablePointer<[Int]>'}}
+  //expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and '[Int]') are expected to be equal}}
   takesMutableArrayPointer(&ii)
 
   // We don't allow these conversions outside of function arguments.
@@ -149,14 +151,15 @@ func constPointerArguments(_ p: UnsafeMutablePointer<Int>,
   var i: Int = 0
   var f: Float = 0
   takesConstPointer(&i)
-  takesConstPointer(&f) // expected-error{{cannot convert value of type 'Float' to expected argument type 'Int'}}
+  takesConstPointer(&f) // expected-error{{cannot convert value of type 'UnsafePointer<Float>' to expected argument type 'UnsafePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Float' and 'Int') are expected to be equal}}
   var ii: [Int] = [0, 1, 2]
   var ff: [Float] = [0, 1, 2]
   takesConstPointer(&ii)
-  takesConstPointer(&ff) // expected-error{{cannot convert value of type 'Array<Float>' to expected argument type 'UnsafePointer<Int>'}}
+  takesConstPointer(&ff) // expected-error{{cannot convert value of type 'UnsafePointer<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 'Array<Float>' to expected argument type 'UnsafePointer<Int>'}}
+  takesConstPointer(ff) // expected-error{{cannot convert value of type 'UnsafePointer<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
@@ -258,9 +261,11 @@ func stringArguments(_ s: String) {
   takesMutableVoidPointer(s) // expected-error{{cannot convert value of type 'String' to expected argument type 'UnsafeMutableRawPointer${diag_suffix}'}}
   takesMutableRawPointer(s) // expected-error{{cannot convert value of type 'String' to expected argument type 'UnsafeMutableRawPointer${diag_suffix}'}}
   takesMutableInt8Pointer(s) // expected-error{{cannot convert value of type 'String' to expected argument type 'UnsafeMutablePointer<Int8>${diag_suffix}'}}
-  takesMutableInt8Pointer(&s) // expected-error{{cannot convert value of type 'String' to expected argument type 'Int8'}}
+  takesMutableInt8Pointer(&s) // expected-error{{cannot convert value of type 'UnsafeMutablePointer<String>' to expected argument type 'UnsafeMutablePointer<Int8>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('String' and 'Int8') are expected to be equal}}
   takesMutablePointer(s) // expected-error{{cannot convert value of type 'String' to expected argument type 'UnsafeMutablePointer<Int>${diag_suffix}'}}
-  takesMutablePointer(&s) // expected-error{{cannot convert value of type 'String' to expected argument type 'Int'}}
+  takesMutablePointer(&s) // expected-error{{cannot convert value of type 'UnsafeMutablePointer<String>' to expected argument type 'UnsafeMutablePointer<Int>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('String' and 'Int') are expected to be equal}}
 }
 
 
@@ -319,7 +324,8 @@ func addressConversion(p: UnsafeMutablePointer<Int>, x: Int) {
 func f19478919() {
   var viewport: Int = 1 // intentionally incorrect type, not Int32
   func GLKProject(_ a : UnsafeMutablePointer<Int32>) {}
-  GLKProject(&viewport)  // expected-error {{cannot convert value of type 'Int' to expected argument type 'Int32'}}
+  GLKProject(&viewport)  // expected-error {{cannot convert value of type 'UnsafeMutablePointer<Int>' to expected argument type 'UnsafeMutablePointer<Int32>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and 'Int32') are expected to be equal}}
 
   func GLKProjectUP(_ a : UnsafePointer<Int32>) {}
   func UP_Void(_ a : UnsafeRawPointer) {}
@@ -341,7 +347,7 @@ 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 'Array<Int>' to expected argument type 'UnsafeMutablePointer<Int32>'}}
+  UMP(&pipe2) // expected-error {{cannot convert value of type 'UnsafeMutablePointer<Int>' to expected argument type 'UnsafeMutablePointer<Int32>'}}
   // expected-note@-1 {{arguments to generic parameter 'Pointee' ('Int' and 'Int32') are expected to be equal}}
 
 

test/Parse/pointer_conversion_objc.swift.gyb

@@ -63,12 +63,14 @@ func autoreleasingPointerArguments(p: UnsafeMutablePointer<Int>,
   takesAutoreleasingPointer(&c)
   takesAutoreleasingPointer(c) // expected-error{{cannot convert value of type 'C' to expected argument type 'AutoreleasingUnsafeMutablePointer<C>${diag_suffix}'}}
   var d: D = D()
-  takesAutoreleasingPointer(&d) // expected-error{{cannot convert value of type 'D' to expected argument type 'C'}}
+  takesAutoreleasingPointer(&d) // expected-error{{cannot convert value of type 'AutoreleasingUnsafeMutablePointer<D>' to expected argument type 'AutoreleasingUnsafeMutablePointer<C>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('D' and 'C') are expected to be equal}}
   takesAutoreleasingPointer(d) // expected-error{{cannot convert value of type 'D' to expected argument type 'AutoreleasingUnsafeMutablePointer<C>${diag_suffix}'}}
   var cc: [C] = [C(), C()]
   var dd: [D] = [D(), D()]
-  takesAutoreleasingPointer(&cc) // expected-error{{cannot convert value of type '[C]' to expected argument type 'C'}}
-  takesAutoreleasingPointer(&dd) // expected-error{{cannot convert value of type '[D]' to expected argument type 'C'}}
-
+  takesAutoreleasingPointer(&cc) // expected-error{{cannot convert value of type 'AutoreleasingUnsafeMutablePointer<[C]>' to expected argument type 'AutoreleasingUnsafeMutablePointer<C>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('[C]' and 'C') are expected to be equal}}
+  takesAutoreleasingPointer(&dd) // expected-error{{cannot convert value of type 'AutoreleasingUnsafeMutablePointer<[D]>' to expected argument type 'AutoreleasingUnsafeMutablePointer<C>'}}
+  // expected-note@-1 {{arguments to generic parameter 'Pointee' ('[D]' and 'C') are expected to be equal}}
   let _: AutoreleasingUnsafeMutablePointer<C> = &c // expected-error {{use of extraneous '&'}}
 }