Revert "Sema: Emit diagnostics when walking into collection literals with defaulted types"

This reverts commit f608802cfe.

lib/Sema/MiscDiagnostics.cpp

@@ -112,15 +112,13 @@ static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
     SmallPtrSet<DeclRefExpr*, 4> AlreadyDiagnosedBitCasts;
 
     bool IsExprStmt;
-    bool HasReachedSemanticsProvidingExpr;
 
     ASTContext &Ctx;
     const DeclContext *DC;
 
   public:
     DiagnoseWalker(const DeclContext *DC, bool isExprStmt)
-        : IsExprStmt(isExprStmt), HasReachedSemanticsProvidingExpr(false),
-          Ctx(DC->getASTContext()), DC(DC) {}
+        : IsExprStmt(isExprStmt), Ctx(DC->getASTContext()), DC(DC) {}
 
     MacroWalking getMacroWalkingBehavior() const override {
       return MacroWalking::Expansion;
@@ -139,16 +137,6 @@ static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
     bool shouldWalkIntoTapExpression() override { return false; }
 
     PreWalkResult<Expr *> walkToExprPre(Expr *E) override {
-      if (auto collection = dyn_cast<CollectionExpr>(E)) {
-        if (collection->isTypeDefaulted()) {
-          // Diagnose type defaulted collection literals in subexpressions as
-          // warnings to preserve source compatibility.
-          diagnoseTypeDefaultedCollectionExpr(
-              collection, Ctx,
-              /*downgradeToWarning=*/HasReachedSemanticsProvidingExpr);
-        }
-      }
-
       // See through implicit conversions of the expression.  We want to be able
       // to associate the parent of this expression with the ultimate callee.
       auto Base = E;
@@ -356,11 +344,6 @@ static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
         checkBorrowExpr(borrowExpr);
       }
 
-      if (!HasReachedSemanticsProvidingExpr &&
-          E == E->getSemanticsProvidingExpr()) {
-        HasReachedSemanticsProvidingExpr = true;
-      }
-
       return Action::Continue(E);
     }
 
@@ -508,34 +491,25 @@ static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
       return false;
     }
 
-    /// Diagnose a collection literal with a defaulted type such as \c [Any].
-    static void diagnoseTypeDefaultedCollectionExpr(CollectionExpr *c,
-                                                    ASTContext &ctx,
-                                                    bool downgradeToWarning) {
-      // Produce a diagnostic with a fixit to add the defaulted type as an
-      // explicit annotation.
-      auto &diags = ctx.Diags;
-
-      if (c->getNumElements() == 0) {
-        InFlightDiagnostic inFlight =
-            diags.diagnose(c->getLoc(), diag::collection_literal_empty);
-        inFlight.highlight(c->getSourceRange());
-
-        if (downgradeToWarning) {
-          inFlight.limitBehavior(DiagnosticBehavior::Warning);
-        }
-      } else {
+    /// We have a collection literal with a defaulted type, e.g. of [Any].  Emit
+    /// an error if it was inferred to this type in an invalid context, which is
+    /// one in which the parent expression is not itself a collection literal.
+    void checkTypeDefaultedCollectionExpr(CollectionExpr *c) {
+      // If the parent is a non-expression, or is not itself a literal, then
+      // produce an error with a fixit to add the type as an explicit
+      // annotation.
+      if (c->getNumElements() == 0)
+        Ctx.Diags.diagnose(c->getLoc(), diag::collection_literal_empty)
+            .highlight(c->getSourceRange());
+      else {
         assert(c->getType()->hasTypeRepr() &&
                "a defaulted type should always be printable");
-        InFlightDiagnostic inFlight = diags.diagnose(
-            c->getLoc(), diag::collection_literal_heterogeneous, c->getType());
-        inFlight.highlight(c->getSourceRange());
-        inFlight.fixItInsertAfter(c->getEndLoc(),
-                                  " as " + c->getType()->getString());
-
-        if (downgradeToWarning) {
-          inFlight.limitBehavior(DiagnosticBehavior::Warning);
-        }
+        Ctx.Diags
+            .diagnose(c->getLoc(), diag::collection_literal_heterogeneous,
+                      c->getType())
+            .highlight(c->getSourceRange())
+            .fixItInsertAfter(c->getEndLoc(),
+                              " as " + c->getType()->getString());
       }
     }
 
@@ -1421,6 +1395,16 @@ static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
 
   DiagnoseWalker Walker(DC, isExprStmt);
   const_cast<Expr *>(E)->walk(Walker);
+
+  // Diagnose uses of collection literals with defaulted types at the top
+  // level.
+  if (auto collection =
+          dyn_cast<CollectionExpr>(E->getSemanticsProvidingExpr())) {
+    if (collection->isTypeDefaulted()) {
+      Walker.checkTypeDefaultedCollectionExpr(
+          const_cast<CollectionExpr *>(collection));
+    }
+  }
 }
 
 

test/Constraints/array_literal.swift

@@ -126,6 +126,11 @@ func defaultToAny(i: Int, s: String) {
   // expected-error@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
   let _: Int = a1  // expected-error{{value of type '[Any]'}}
 
+  let _ = ([1, "a"])
+  // expected-error@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
+  let _ = [1, true, []]
+  // expected-error@-1:11 {{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
+
   let a2: Array = [1, "a", 3.5]
   // expected-error@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
   let _: Int = a2  // expected-error{{value of type '[Any]'}}
@@ -146,9 +151,7 @@ func defaultToAny(i: Int, s: String) {
   let _: [Any] = [1, "a", 3.5]
   let _: [Any] = [1, "a", [3.5, 3.7, 3.9]]
   let _: [Any] = [1, "a", [3.5, "b", 3]]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
   let _: [Any] = [1, [2, [3]]]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
 
   func f1() -> [Any] {
     []
@@ -157,41 +160,25 @@ func defaultToAny(i: Int, s: String) {
   let _: [Any?] = [1, "a", nil, 3.5]
   let _: [Any?] = [1, "a", nil, [3.5, 3.7, 3.9]]
   let _: [Any?] = [1, "a", nil, [3.5, "b", nil]]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any?]'; add explicit type annotation if this is intentional}}
   let _: [Any?] = [1, [2, [3]]]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
   let _: [Any?] = [1, nil, [2, nil, [3]]]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any?]'; add explicit type annotation if this is intentional}}
 
   let a6 = [B(), C()]
   let _: Int = a6 // expected-error{{value of type '[A]'}}
   
   let a7: some Collection = [1, "Swift"]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}} {{41-41= as [Any]}}
   let _: (any Sequence)? = [1, "Swift"]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
   let _: any Sequence = [1, nil, "Swift"]
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any?]'; add explicit type annotation if this is intentional}}
-  let _ = [1, true, ([], 1)]
-  // expected-error@-1 {{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
-  // expected-warning@-2 {{empty collection literal requires an explicit type}}
   let _ = true ? [] : []
-  // expected-warning@-1{{empty collection literal requires an explicit type}}
   let _ = (true, ([1, "Swift"]))
-  //expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
-  let _ = ([1, true])
-  //expected-error@-1{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
 
   func f2<T>(_: [T]) {}
 
   func f3<T>() -> [T]? {}
 
   f2([])
-  // expected-warning@-1{{empty collection literal requires an explicit type}}
   f2([1, nil, ""])
-  // expected-warning@-1{{heterogeneous collection literal could only be inferred to '[Any?]'; add explicit type annotation if this is intentional}}
   _ = f3() ?? []
-  // expected-warning@-1{{empty collection literal requires an explicit type}}
 }
 
 func noInferAny(iob: inout B, ioc: inout C) {

test/Constraints/casts.swift

@@ -338,7 +338,6 @@ func test_compatibility_coercions(_ arr: [Int], _ optArr: [Int]?, _ dict: [Strin
 
   // The array can also be inferred to be [Any].
   _ = ([] ?? []) as Array // expected-warning {{left side of nil coalescing operator '??' has non-optional type '[Any]', so the right side is never used}}
-  // expected-warning@-1{{empty collection literal requires an explicit type}}
 
   // rdar://88334481 – Don't apply the compatibility logic for collection literals.
   typealias Magic<T> = T

test/Constraints/casts_swift6.swift

@@ -57,7 +57,6 @@ func test_compatibility_coercions(_ arr: [Int], _ optArr: [Int]?, _ dict: [Strin
 
   // The array can also be inferred to be [Any].
   _ = ([] ?? []) as Array // expected-warning {{left side of nil coalescing operator '??' has non-optional type '[Any]', so the right side is never used}}
-  // expected-warning@-1 {{empty collection literal requires an explicit type}}
 
   // Cases from rdar://88334481
   typealias Magic<T> = T

test/Constraints/construction.swift

@@ -175,7 +175,6 @@ do {
 
 // rdar://problem/34670592 - Compiler crash on heterogeneous collection literal
 _ = Array([1, "hello"]) // Ok
-// expected-warning@-1 {{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
 
 func init_via_non_const_metatype(_ s1: S1.Type) {
   _ = s1(i: 42) // expected-error {{initializing from a metatype value must reference 'init' explicitly}} {{9-9=.init}}

test/Constraints/dictionary_literal.swift

@@ -120,6 +120,8 @@ class B : A { }
 class C : A { }
 
 func testDefaultExistentials() {
+  let _ = ["a": ["b": ["c": ["d", 1, true]]]]
+
   let _ = ["a" : 1, "b" : 2.5, "c" : "hello"]
   // expected-error@-1{{heterogeneous collection literal could only be inferred to '[String : Any]'; add explicit type annotation if this is intentional}}{{46-46= as [String : Any]}}
 
@@ -139,7 +141,6 @@ func testDefaultExistentials() {
            "b": ["a", 2, 3.14159],
            "c": ["a": 2, "b": 3.5]]
   // expected-error@-3{{heterogeneous collection literal could only be inferred to '[String : Any]'; add explicit type annotation if this is intentional}}
-  // expected-warning@-3{{heterogeneous collection literal could only be inferred to '[Any]'; add explicit type annotation if this is intentional}}
 
   let d3 = ["b" : B(), "c" : C()]
   let _: Int = d3 // expected-error{{value of type '[String : A]'}}

test/Constraints/subscript.swift

@@ -104,7 +104,6 @@ extension Int {
 let _ = 1["1"]  // expected-error {{ambiguous use of 'subscript(_:)'}}
 
 let squares = [ 1, 2, 3 ].reduce([:]) { (dict, n) in
-  // expected-warning@-1 {{empty collection literal requires an explicit type}}
   var dict = dict
   dict[n] = n * n
   return dict

test/IDE/print_usrs_opaque_types.swift

@@ -9,20 +9,17 @@
 func testUnifyingGenericParams<T, U>(x: T) -> some Collection where T == U {
   // expected-warning@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
   return []
-  // expected-warning@-1 {{empty collection literal requires an explicit type}}
 }
 
 // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test0C22UnifyingGenericParams21xQrx_tSlRz7ElementQzRs_r0_lF
 func testUnifyingGenericParams2<T, U>(x: T) -> some Collection where T: Collection, U == T.Element {
   return []
-  // expected-warning@-1 {{empty collection literal requires an explicit type}}
 }
 
 // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test0C24ConcretizingGenericParam1xQrSi_tSiRszlF
 func testConcretizingGenericParam<T>(x: T) -> some Collection where T == Int {
   // expected-warning@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
   return []
-  // expected-warning@-1 {{empty collection literal requires an explicit type}}
 }
 
 struct GenericContext<T> {
@@ -30,13 +27,11 @@ struct GenericContext<T> {
   func testUnifyingGenericParams<U>(x: T) -> some Collection where T == U {
     // expected-warning@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextV0c8UnifyingD7Params21xQrx_tSlRz7ElementQzRsd__lF
   func testUnifyingGenericParams2<U>(x: T) -> some Collection where T: Collection, U == T.Element {
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextVyQrxcqd__Rszluip
@@ -45,7 +40,6 @@ struct GenericContext<T> {
     // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextVyQrxcqd__Rszluig
     get {
       return []
-      // expected-warning@-1 {{empty collection literal requires an explicit type}}
     }
   }
 }
@@ -54,7 +48,6 @@ extension GenericContext where T == Int {
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextVAASiRszlE0c12ConcretizingD5Param1xQrSi_tF
   func testConcretizingGenericParam(x: T) -> some Collection {
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 }
 
@@ -65,7 +58,6 @@ extension TooGenericTooContext where T == U {
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test010TooGenericD7ContextVAAq_RszrlE0c8UnifyingE6Params1xQrx_tF
   func testUnifyingGenericParams(x: T) -> some Collection {
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 }
 
@@ -73,14 +65,12 @@ extension TooGenericTooContext where T: Collection, U == T.Element {
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test010TooGenericD7ContextVAASlRz7ElementQzRs_rlE0c8UnifyingE7Params21xQrx_tF
   func testUnifyingGenericParams2(x: T) -> some Collection {
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 }
 extension TooGenericTooContext where T == Int {
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test010TooGenericD7ContextVAASiRszrlE0c12ConcretizingE5Param1xQrSi_tF
   func testConcretizingGenericParam(x: T) -> some Collection {
     return []
-    // expected-warning@-1 {{empty collection literal requires an explicit type}}
   }
 }
 

test/Parse/matching_patterns.swift

@@ -307,8 +307,6 @@ do {
   while case let _ as [Derived] = arr {}
   // expected-warning@-1 {{'let' pattern has no effect; sub-pattern didn't bind any variables}}
 
-  // FIXME: https://github.com/apple/swift/issues/61850
-  // expected-warning@+1 {{heterogeneous collection literal could only be inferred to '[[Base]]'; add explicit type annotation if this is intentional}}
   for case _ as [Derived] in [arr] {}
 
   if case is [Derived] = arr {}

test/Parse/matching_patterns_reference_bindings.swift

@@ -328,8 +328,6 @@ do {
   while case let _ as [Derived] = arr {}
   // expected-warning@-1 {{'let' pattern has no effect; sub-pattern didn't bind any variables}}
 
-  // FIXME: https://github.com/apple/swift/issues/61850
-  // expected-warning@+1 {{heterogeneous collection literal could only be inferred to '[[Base]]'; add explicit type annotation if this is intentional}}
   for case _ as [Derived] in [arr] {}
 
   if case is [Derived] = arr {}

test/expr/cast/objc_coerce_array.swift

@@ -7,13 +7,9 @@ var x = 1
 _ = [x] as [NSNumber]
 
 _ = ["x":["y":"z","a":1]] as [String : [String : AnyObject]]
-// expected-warning@-1{{heterogeneous collection literal could only be inferred to '[String : AnyObject]'; add explicit type annotation if this is intentiona}}
 _ = ["x":["z",1]] as [String : [AnyObject]]
-// expected-warning@-1{{heterogeneous collection literal could only be inferred to '[AnyObject]'; add explicit type annotation if this is intentional}}
 _ = [["y":"z","a":1]] as [[String : AnyObject]]
-// expected-warning@-1{{heterogeneous collection literal could only be inferred to '[String : AnyObject]'; add explicit type annotation if this is intentional}}
 _ = [["z",1]] as [[AnyObject]]
-// expected-warning@-1{{heterogeneous collection literal could only be inferred to '[AnyObject]'; add explicit type annotation if this is intentional}}
 
 var y: Any = 1