Make @abi type comparison ignore tuple labels

Author: beccadax

lib/Sema/TypeCheckAttr.cpp

@@ -9425,6 +9425,22 @@ class ABIDeclChecker : public ASTComparisonVisitor<ABIDeclChecker> {
       if (!normConstraint->isExistentialType())
         return normConstraint;
     }
+    
+    // Tuples: Remove labels.
+    if (auto tuple = original->getAs<TupleType>()) {
+      bool needsNormalization = false;
+      SmallVector<TupleTypeElt, 8> unlabeledElements;
+      
+      for (auto elem : tuple->getElements()) {
+        needsNormalization |= !elem.getName().empty();
+        unlabeledElements.push_back(elem.getWithoutName());
+      }
+      
+      if (!needsNormalization)
+        return tuple;
+      
+      return TupleType::get(unlabeledElements, tuple->getASTContext());
+    }
 
     // TODO: Allow Optional/non-Optional variance when ABI-compatible?
     // TODO: Allow variance in exact class of object?

test/attr/attr_abi.swift

@@ -378,6 +378,15 @@ func intForFloatParam(_: Int) -> Int { fatalError() } // expected-note @:26 {{sh
 @abi(func floatForIntResult(_: Int) -> Float) // expected-error @:40 {{type 'Float' in '@abi' should match 'Int'}}
 func intForFloatResult(_: Int) -> Int { fatalError() } // expected-note @:35 {{should match type here}}
 
+@abi(func labeledForUnlabeledTuple(_: (x: Int, y: Int)))
+func labeledForUnlabeledTuple(_: (Int, Int)) {}
+
+@abi(func unlabeledForLabeledTuple(_: (Int, Int)))
+func unlabeledForLabeledTuple(_: (x: Int, y: Int)) {}
+
+@abi(func labeledForLabeledTuple(_: (x: Int, y: Int)))
+func labeledForLabeledTuple(_: (a: Int, b: Int)) {}
+
 @abi(
   func testDefaultArguments(
     a: Int,