[CSGen] Use addJoinConstraint for joining array literal element types.

Author: hborla

lib/Sema/CSGen.cpp

@@ -1803,31 +1803,28 @@ namespace {
 
       auto locator = CS.getConstraintLocator(expr);
       auto contextualType = CS.getContextualType(expr);
-      Type contextualArrayType = nullptr;
-      Type contextualArrayElementType = nullptr;
-      
+
+      auto joinElementTypes = [&](Optional<Type> elementType) {
+        const auto elements = expr->getElements();
+        unsigned index = 0;
+
+        using Iterator = decltype(elements)::iterator;
+        CS.addJoinConstraint<Iterator>(locator, elements.begin(), elements.end(),
+                                       elementType, [&](const auto it) {
+          auto *locator = CS.getConstraintLocator(expr, LocatorPathElt::TupleElement(index++));
+          return std::make_pair(CS.getType(*it), locator);
+        });
+      };
+
       // If a contextual type exists for this expression, apply it directly.
       Optional<Type> arrayElementType;
       if (contextualType &&
           (arrayElementType = ConstraintSystem::isArrayType(contextualType))) {
-        // Is the array type a contextual type
-        contextualArrayType = contextualType;
-        contextualArrayElementType = *arrayElementType;
-
         CS.addConstraint(ConstraintKind::LiteralConformsTo, contextualType,
                          arrayProto->getDeclaredType(),
                          locator);
-        
-        unsigned index = 0;
-        for (auto element : expr->getElements()) {
-          CS.addConstraint(ConstraintKind::Conversion,
-                           CS.getType(element),
-                           contextualArrayElementType,
-                           CS.getConstraintLocator(
-                               expr, LocatorPathElt::TupleElement(index++)));
-        }
-        
-        return contextualArrayType;
+        joinElementTypes(arrayElementType);
+        return contextualType;
       }
 
       // Produce a specialized diagnostic if this is an attempt to initialize
@@ -1893,14 +1890,7 @@ namespace {
 
       // Introduce conversions from each element to the element type of the
       // array.
-      unsigned index = 0;
-      for (auto element : expr->getElements()) {
-        CS.addConstraint(ConstraintKind::Conversion,
-                         CS.getType(element),
-                         arrayElementTy,
-                         CS.getConstraintLocator(
-                           expr, LocatorPathElt::TupleElement(index++)));
-      }
+      joinElementTypes(arrayElementTy);
 
       // The array element type defaults to 'Any'.
       CS.addConstraint(ConstraintKind::Defaultable, arrayElementTy,

lib/Sema/CSSimplify.cpp

@@ -4216,6 +4216,7 @@ bool ConstraintSystem::repairFailures(
 
       conversionsOrFixes.push_back(CollectionElementContextualMismatch::create(
           *this, lhs, rhs, getConstraintLocator(locator)));
+      break;
     }
 
     // Drop the `tuple element` locator element so that all tuple element

test/Constraints/diagnostics.swift

@@ -338,7 +338,7 @@ variadic(arrayWithOtherEltType) // expected-error {{cannot convert value of type
 variadic(1, arrayWithOtherEltType) // expected-error {{cannot convert value of type '[String]' to expected argument type 'Int'}}
 
 // FIXME: SR-11104
-variadic(["hello", "world"]) // expected-error 2 {{cannot convert value of type 'String' to expected element type 'Int'}}
+variadic(["hello", "world"]) // expected-error {{cannot convert value of type 'String' to expected element type 'Int'}}
 // expected-error@-1 {{cannot pass array of type '[Int]' as variadic arguments of type 'Int'}}
 // expected-note@-2 {{remove brackets to pass array elements directly}}
 

test/Parse/pointer_conversion.swift.gyb

@@ -164,7 +164,7 @@ func constPointerArguments(_ p: UnsafeMutablePointer<Int>,
   takesConstPointer([0, 1, 2])
   // <rdar://problem/22308330> QoI: CSDiags doesn't handle array -> pointer impl conversions well
   takesConstPointer([0.0, 1.0, 2.0])
-  // expected-error@-1 3 {{cannot convert value of type 'Double' to expected element type 'Int'}}
+  // expected-error@-1 {{cannot convert value of type 'Double' to expected element type 'Int'}}
 
   // We don't allow these conversions outside of function arguments.
   var x: UnsafePointer<Int> = &i // expected-error {{use of extraneous '&'}}

test/expr/cast/as_coerce.swift

@@ -84,13 +84,13 @@ c3 as C4 // expected-error {{'C3' is not convertible to 'C4'; did you mean to us
 Double(1) as Double as String // expected-error{{cannot convert value of type 'Double' to type 'String' in coercion}}
 ["awd"] as [Int] // expected-error{{cannot convert value of type 'String' to expected element type 'Int'}}
 ([1, 2, 1.0], 1) as ([String], Int)
-// expected-error@-1 2 {{cannot convert value of type 'Int' to expected element type 'String'}}
+// expected-error@-1 {{cannot convert value of type 'Int' to expected element type 'String'}}
 // expected-error@-2   {{cannot convert value of type 'Double' to expected element type 'String'}}
 [[1]] as [[String]] // expected-error{{cannot convert value of type 'Int' to expected element type 'String'}}
 (1, 1.0) as (Int, Int) // expected-error{{cannot convert value of type '(Int, Double)' to type '(Int, Int)' in coercion}}
 (1.0, 1, "asd") as (String, Int, Float) // expected-error{{cannot convert value of type '(Double, Int, String)' to type '(String, Int, Float)' in coercion}}
 (1, 1.0, "a", [1, 23]) as (Int, Double, String, [String])
-// expected-error@-1 2 {{cannot convert value of type 'Int' to expected element type 'String'}}
+// expected-error@-1 {{cannot convert value of type 'Int' to expected element type 'String'}}
 
 _ = [1] as! [String] // OK
 _ = [(1, (1, 1))] as! [(Int, (String, Int))] // OK