Merge pull request #64733 from xedin/rdar-106775969

[CSSimplify] Exploaded tuple argument should assume param's label if …

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -1635,7 +1635,22 @@ static ConstraintSystem::TypeMatchResult matchCallArguments(
       SmallVector<SynthesizedArg, 4> synthesizedArgs;
       for (unsigned i = 0, n = argTuple->getNumElements(); i != n; ++i) {
         const auto &elt = argTuple->getElement(i);
-        AnyFunctionType::Param argument(elt.getType(), elt.getName());
+
+        // If tuple doesn't have a label for its first element
+        // and parameter does, let's assume parameter's label
+        // to aid argument matching. For example:
+        //
+        // \code
+        // func test(val: Int, _: String) {}
+        //
+        // test(val: (42, "")) // expands into `(val: 42, "")`
+        // \endcode
+        Identifier label = elt.getName();
+        if (i == 0 && !elt.hasName() && params[0].hasLabel()) {
+          label = params[0].getLabel();
+        }
+
+        AnyFunctionType::Param argument(elt.getType(), label);
         synthesizedArgs.push_back(SynthesizedArg{i, argument});
         argsWithLabels.push_back(argument);
       }

test/Constraints/pack-expansion-expressions.swift

@@ -331,13 +331,20 @@ func test_pack_expansions_with_closures() {
 // rdar://107151854 - crash on invalid due to specialized pack expansion
 func test_pack_expansion_specialization() {
   struct Data<each T> {
-    init(_: repeat each T) {} // expected-note {{'init(_:)' declared here}}
+    init(_: repeat each T) {} // expected-note 2 {{'init(_:)' declared here}}
+    init(vals: repeat each T) {} // expected-note 2 {{'init(vals:)' declared here}}
   }
 
   _ = Data<Int>() // expected-error {{missing argument for parameter #1 in call}}
   _ = Data<Int>(0) // Ok
   _ = Data<Int, String>(42, "") // Ok
   _ = Data<Int>(42, "") // expected-error {{extra argument in call}}
+  _ = Data<Int, String>((42, ""))
+  // expected-error@-1 {{initializer expects 2 separate arguments; remove extra parentheses to change tuple into separate arguments}}
+  _ = Data<Int, String, Float>(vals: (42, "", 0))
+  // expected-error@-1 {{initializer expects 3 separate arguments; remove extra parentheses to change tuple into separate arguments}}
+  _ = Data<Int, String, Float>((vals: 42, "", 0))
+  // expected-error@-1 {{initializer expects 3 separate arguments; remove extra parentheses to change tuple into separate arguments}}
 }
 
 // rdar://107280056 - "Ambiguous without more context" with opaque return type + variadics

test/Constraints/tuple_arguments.swift

@@ -1799,3 +1799,9 @@ func variadicSplat() {
     _ = y.count
   }
 }
+
+func tuple_splat_with_a_label() {
+  func test(vals: Int, _: String, _: Float) {} // expected-note 2 {{'test(vals:_:_:)' declared here}}
+  test(vals: (23, "hello", 3.14)) // expected-error {{local function 'test' expects 3 separate arguments; remove extra parentheses to change tuple into separate arguments}}
+  test((vals: 23, "hello", 3.14)) // expected-error {{local function 'test' expects 3 separate arguments; remove extra parentheses to change tuple into separate arguments}}
+}