Merge pull request swiftlang#36609 from xedin/rdar-75409111

[CSGen] Avoid failing due to invalid explicit closure parameters

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -7199,10 +7199,17 @@ bool MissingContextualTypeForNil::diagnoseAsError() {
 }
 
 bool ReferenceToInvalidDeclaration::diagnoseAsError() {
+  auto &DE = getASTContext().Diags;
+
+  // `resolveType` caches results, so there is no way
+  // to suppress and then re-request the diagnostic
+  // via calling `resolveType` on the same `TypeRepr`.
+  if (getAsDecl<ParamDecl>(getAnchor()))
+    return DE.hadAnyError();
+
   auto *decl = castToExpr<DeclRefExpr>(getAnchor())->getDecl();
   assert(decl);
 
-  auto &DE = getASTContext().Diags;
   // This problem should have been already diagnosed during
   // validation of the declaration.
   if (DE.hadAnyError())

lib/Sema/CSGen.cpp

@@ -1984,6 +1984,18 @@ namespace {
           Type externalType;
           if (param->getTypeRepr()) {
             auto declaredTy = CS.getVarType(param);
+
+            // If closure parameter couldn't be resolved, let's record
+            // a fix to make sure that type resolution diagnosed the
+            // problem and replace it with a placeholder, so that solver
+            // can make forward progress (especially important for result
+            // builders).
+            if (declaredTy->hasError()) {
+              CS.recordFix(AllowRefToInvalidDecl::create(
+                  CS, CS.getConstraintLocator(param)));
+              declaredTy = PlaceholderType::get(CS.getASTContext(), param);
+            }
+
             externalType = CS.replaceInferableTypesWithTypeVars(declaredTy,
                                                                 paramLoc);
           } else {

lib/Sema/PreCheckExpr.cpp

@@ -1391,22 +1391,6 @@ namespace {
 /// Perform prechecking of a ClosureExpr before we dive into it.  This returns
 /// true when we want the body to be considered part of this larger expression.
 bool PreCheckExpression::walkToClosureExprPre(ClosureExpr *closure) {
-  auto *PL = closure->getParameters();
-
-  // Validate the parameters.
-  bool hadParameterError = false;
-
-  // If we encounter an error validating the parameter list, don't bail.
-  // Instead, go on to validate any potential result type, and bail
-  // afterwards.  This allows for better diagnostics, and keeps the
-  // closure expression type well-formed.
-  for (auto param : *PL) {
-    hadParameterError |= param->isInvalid();
-  }
-
-  if (hadParameterError)
-    return false;
-
   // If we won't be checking the body of the closure, don't walk into it here.
   if (!shouldTypeCheckInEnclosingExpression(closure))
     return false;

test/Constraints/result_builder_diags.swift

@@ -675,3 +675,41 @@ do {
     throw MyError.boom
   }
 }
+
+struct TuplifiedStructWithInvalidClosure {
+  var condition: Bool
+
+  @TupleBuilder var unknownParameter: some Any {
+    if let cond = condition {
+      let _ = { (arg: UnknownType) in // expected-error {{cannot find type 'UnknownType' in scope}}
+      }
+      42
+    } else {
+      0
+    }
+  }
+
+  @TupleBuilder var unknownResult: some Any {
+    if let cond = condition {
+      let _ = { () -> UnknownType in // expected-error {{cannot find type 'UnknownType' in scope}}
+      }
+      42
+    } else {
+      0
+    }
+  }
+
+  @TupleBuilder var multipleLevelsDeep: some Any {
+    if let cond = condition {
+      switch MyError.boom {
+      case .boom:
+        let _ = { () -> UnknownType in // expected-error {{cannot find type 'UnknownType' in scope}}
+        }
+      }
+
+      42
+    } else {
+      0
+    }
+  }
+}

test/Constraints/tuple_arguments.swift

@@ -1468,11 +1468,11 @@ let _ = sr4745.enumerated().map { (count, element) in "\(count): \(element)" }
 // SR-4738
 
 let sr4738 = (1, (2, 3))
-[sr4738].map { (x, (y, z)) -> Int in x + y + z }
+[sr4738].map { (x, (y, z)) -> Int in x + y + z } // expected-note 2 {{'x' declared here}}
 // 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 {{cannot find type 'y' in scope}}
-// expected-error@-4 {{cannot find type 'z' in scope}}
+// expected-error@-3 {{cannot find 'y' in scope; did you mean 'x'?}}
+// expected-error@-4 {{cannot find 'z' in scope; did you mean 'x'?}}
 
 // rdar://problem/31892961
 let r31892961_1 = [1: 1, 2: 2]
@@ -1482,9 +1482,8 @@ 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 {{cannot find type 'index' in scope}}
-  // expected-error@-4 {{cannot find type 'val' in scope}}
   val + 1
+  // expected-error@-1 {{cannot find 'val' in scope}}
 }
 
 let r31892961_3 = (x: 1, y: 42)
@@ -1695,7 +1694,7 @@ class Mappable<T> {
 }
 
 let x = Mappable(())
-// expected-note@-1 2{{'x' declared here}}
+// expected-note@-1 4{{'x' declared here}}
 x.map { (_: Void) in return () }
 x.map { (_: ()) in () }