swiftlang · CodaFi · Nov 11, 2019 · Nov 9, 2019 · xedin · Nov 9, 2019
diff --git a/include/swift/AST/Decl.h b/include/swift/AST/Decl.h
@@ -5214,7 +5214,7 @@ enum class ParamSpecifier : uint8_t {
 
 /// A function parameter declaration.
 class ParamDecl : public VarDecl {
-  Identifier ArgumentName;
+  llvm::PointerIntPair<Identifier, 1, bool> ArgumentNameAndDestructured;
   SourceLoc ParameterNameLoc;
   SourceLoc ArgumentNameLoc;
   SourceLoc SpecifierLoc;
@@ -5251,7 +5251,9 @@ class ParamDecl : public VarDecl {
   static ParamDecl *cloneWithoutType(const ASTContext &Ctx, ParamDecl *PD);
 
   /// Retrieve the argument (API) name for this function parameter.
-  Identifier getArgumentName() const { return ArgumentName; }
+  Identifier getArgumentName() const {
+    return ArgumentNameAndDestructured.getPointer();
+  }
 
   /// Retrieve the parameter (local) name for this function parameter.
   Identifier getParameterName() const { return getName(); }
@@ -5270,6 +5272,9 @@ class ParamDecl : public VarDecl {
   TypeRepr *getTypeRepr() const { return TyRepr; }
   void setTypeRepr(TypeRepr *repr) { TyRepr = repr; }
 
+  bool isDestructured() const { return ArgumentNameAndDestructured.getInt(); }
+  void setDestructured(bool repr) { ArgumentNameAndDestructured.setInt(repr); }
+
   DefaultArgumentKind getDefaultArgumentKind() const {
     return static_cast<DefaultArgumentKind>(Bits.ParamDecl.defaultArgumentKind);
   }

diff --git a/include/swift/AST/DiagnosticsParse.def b/include/swift/AST/DiagnosticsParse.def
@@ -893,6 +893,8 @@ ERROR(parameter_operator_keyword_argument,none,
 
 ERROR(parameter_unnamed,none,
       "unnamed parameters must be written with the empty name '_'", ())
+WARNING(parameter_unnamed_warn,none,
+        "unnamed parameters must be written with the empty name '_'", ())
 
 ERROR(parameter_curry_syntax_removed,none,
       "cannot have more than one parameter list", ())

diff --git a/include/swift/Parse/Parser.h b/include/swift/Parse/Parser.h
@@ -1211,6 +1211,9 @@ class Parser {
 
     /// True if we emitted a parse error about this parameter.
     bool isInvalid = false;
+
+    /// True if this parameter is potentially destructuring a tuple argument.
+    bool isPotentiallyDestructured = false;
   };
 
   /// Describes the context in which the given parameter is being parsed.

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
@@ -5914,7 +5914,8 @@ ParamDecl::ParamDecl(SourceLoc specifierLoc,
               VarDecl::Introducer::Let,
               /*IsCaptureList*/ false, parameterNameLoc, parameterName, dc,
               StorageIsNotMutable),
-      ArgumentName(argumentName), ParameterNameLoc(parameterNameLoc),
+      ArgumentNameAndDestructured(argumentName, false),
+      ParameterNameLoc(parameterNameLoc),
       ArgumentNameLoc(argumentNameLoc), SpecifierLoc(specifierLoc) {
   Bits.ParamDecl.SpecifierComputed = false;
   Bits.ParamDecl.defaultArgumentKind =

diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
@@ -2657,7 +2657,7 @@ parseClosureSignatureIfPresent(SmallVectorImpl<CaptureListEntry> &captureList,
   // possible and give a proper fix-it. See SE-0110 for more details.
   auto isTupleDestructuring = [](ParamDecl *param) -> bool {
     auto *typeRepr = param->getTypeRepr();
-    if (!(typeRepr && typeRepr->isInvalid()))
+    if (!(typeRepr && param->isDestructured()))
       return false;
     return !param->hasName() && isa<TupleTypeRepr>(typeRepr);
   };

diff --git a/lib/Parse/ParsePattern.cpp b/lib/Parse/ParsePattern.cpp
@@ -363,12 +363,18 @@ Parser::parseParameterClause(SourceLoc &leftParenLoc,
         if (param.Type) {
           // Mark current parameter type as invalid so it is possible
           // to diagnose it as destructuring of the closure parameter list.
-          param.Type->setInvalid();
-          param.isInvalid = true;
+          param.isPotentiallyDestructured = true;
           if (!isClosure) {
             // Unnamed parameters must be written as "_: Type".
             diagnose(typeStartLoc, diag::parameter_unnamed)
                 .fixItInsert(typeStartLoc, "_: ");
+          } else {
+            // Unnamed parameters were accidentally possibly accepted after
+            // SE-110 depending on the kind of declaration.  We now need to
+            // warn about the misuse of this syntax and offer to
+            // fix it.
+            diagnose(typeStartLoc, diag::parameter_unnamed_warn)
+              .fixItInsert(typeStartLoc, "_: ");
           }
         }
       } else {
@@ -492,7 +498,13 @@ mapParsedParameters(Parser &parser,
     // If we diagnosed this parameter as a parse error, propagate to the decl.
     if (paramInfo.isInvalid)
       param->setInvalid();
-
+
+    // If we need to diagnose this parameter as a destructuring, propagate that
+    // to the decl.
+    // FIXME: This is a terrible way to catch this.
+    if (paramInfo.isPotentiallyDestructured)
+      param->setDestructured(true);
+
     // If a type was provided, create the type for the parameter.
     if (auto type = paramInfo.Type) {
       // If 'inout' was specified, turn the type into an in-out type.

diff --git a/test/Constraints/tuple_arguments.swift b/test/Constraints/tuple_arguments.swift
@@ -1470,6 +1470,9 @@ let _ = sr4745.enumerated().map { (count, element) in "\(count): \(element)" }
 let sr4738 = (1, (2, 3))
 [sr4738].map { (x, (y, z)) -> Int in x + y + z }
 // expected-error@-1 {{closure tuple parameter does not support destructuring}} {{20-26=arg1}} {{38-38=let (y, z) = arg1; }}
+// expected-warning@-2 {{unnamed parameters must be written with the empty name '_'}} {{20-20=_: }}
+// expected-error@-3 {{use of undeclared type 'y'}}
+// expected-error@-4 {{use of undeclared type 'z'}}
 
 // rdar://problem/31892961
 let r31892961_1 = [1: 1, 2: 2]
@@ -1478,6 +1481,9 @@ r31892961_1.forEach { (k, v) in print(k + v) }
 let r31892961_2 = [1, 2, 3]
 let _: [Int] = r31892961_2.enumerated().map { ((index, val)) in
   // expected-error@-1 {{closure tuple parameter does not support destructuring}} {{48-60=arg0}} {{3-3=\n  let (index, val) = arg0\n  }}
+  // expected-warning@-2 {{unnamed parameters must be written with the empty name '_'}} {{48-48=_: }}
+  // expected-error@-3 {{use of undeclared type 'index'}}
+  // expected-error@-4 {{use of undeclared type 'val'}}
   val + 1
 }
 
@@ -1490,12 +1496,16 @@ let r31892961_4 = (1, 2)
 _ = [r31892961_4].map { x, y in x + y }
 
 let r31892961_5 = (x: 1, (y: 2, (w: 3, z: 4)))
-[r31892961_5].map { (x: Int, (y: Int, (w: Int, z: Int))) in x + y }
+[r31892961_5].map { (x: Int, (y: Int, (w: Int, z: Int))) in x + y } // expected-note {{'x' declared here}}
 // expected-error@-1 {{closure tuple parameter does not support destructuring}} {{30-56=arg1}} {{61-61=let (y, (w, z)) = arg1; }}
+// expected-warning@-2 {{unnamed parameters must be written with the empty name '_'}} {{30-30=_: }}
+// expected-error@-3{{use of unresolved identifier 'y'; did you mean 'x'?}}
 
 let r31892961_6 = (x: 1, (y: 2, z: 4))
-[r31892961_6].map { (x: Int, (y: Int, z: Int)) in x + y }
+[r31892961_6].map { (x: Int, (y: Int, z: Int)) in x + y } // expected-note {{'x' declared here}}
 // expected-error@-1 {{closure tuple parameter does not support destructuring}} {{30-46=arg1}} {{51-51=let (y, z) = arg1; }}
+// expected-warning@-2 {{unnamed parameters must be written with the empty name '_'}} {{30-30=_: }}
+// expected-error@-3{{use of unresolved identifier 'y'; did you mean 'x'?}}
 
 // rdar://problem/32214649 -- these regressed in Swift 4 mode
 // with SE-0110 because of a problem in associated type inference

diff --git a/test/decl/func/functions.swift b/test/decl/func/functions.swift
@@ -192,8 +192,8 @@ func bogusDestructuring() {
     func registerCallback(_ callback: @escaping (Bar?) -> Void) {} // expected-note {{found this candidate}}
   }
 
-  Foo().registerCallback { ([Bar]) in } // expected-error {{'<<error type>>' is not convertible to '[Bar]'}}
-  Foo().registerCallback { ([String: Bar]) in } // expected-error {{'<<error type>>' is not convertible to '[Bar]'}}
+  Foo().registerCallback { ([Bar]) in } // expected-warning {{unnamed parameters must be written with the empty name '_'}} {{29-29=_: }}
+  Foo().registerCallback { ([String: Bar]) in }// expected-warning {{unnamed parameters must be written with the empty name '_'}} {{29-29=_: }}
   Foo().registerCallback { (Bar?) in } // expected-error {{ambiguous use of 'registerCallback'}}
   // expected-error@-1 {{expected parameter name followed by ':'}}
   // expected-error@-2 {{expected ',' separator}}

diff --git a/...ompiler_crashers_fixed/28723-unreachable-executed-at-swift-lib-sema-csdiag-cpp-4012.swift b/...ompiler_crashers_fixed/28723-unreachable-executed-at-swift-lib-sema-csdiag-cpp-4012.swift
@@ -6,6 +6,7 @@
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
 // rdar://56144412
+// XFAIL: asserts
 // RUN: not %target-swift-frontend %s -emit-ir
 func t(UInt=__FUNCTION__
 func&t(