Merge pull request #14084 from rudkx/partial-fix-rdar24097075

Fix one source of problems with allowing @NoEscape functions to escape.

Author: rudkx

lib/Sema/MiscDiagnostics.cpp

@@ -241,6 +241,14 @@ static void diagSyntacticUseRestrictions(TypeChecker &TC, const Expr *E,
         });
       }
 
+      if (auto *AE = dyn_cast<CollectionExpr>(E)) {
+        visitCollectionElements(AE, [&](unsigned argIndex, Expr *arg) {
+          arg = lookThroughArgument(arg);
+          if (auto *DRE = dyn_cast<DeclRefExpr>(arg))
+            checkNoEscapeParameterUse(DRE, AE, OperandKind::Argument);
+        });
+      }
+
       // Check decl refs in withoutActuallyEscaping blocks.
       if (auto MakeEsc = dyn_cast<MakeTemporarilyEscapableExpr>(E)) {
         if (auto DRE =
@@ -417,6 +425,13 @@ static void diagSyntacticUseRestrictions(TypeChecker &TC, const Expr *E,
       argExprVisitArguments(arg, fn);
     }
 
+    static void visitCollectionElements(CollectionExpr *collection,
+                               llvm::function_ref<void(unsigned, Expr*)> fn) {
+      auto elts = collection->getElements();
+      for (auto i : indices(elts))
+        fn(i, elts[i]);
+    }
+
     static Expr *lookThroughArgument(Expr *arg) {
       while (1) {
         if (auto conv = dyn_cast<ImplicitConversionExpr>(arg))

test/attr/attr_noescape.swift

@@ -10,11 +10,24 @@ func doesEscape(_ fn : @escaping () -> Int) {}
 func takesGenericClosure<T>(_ a : Int, _ fn : @noescape () -> T) {} // expected-warning{{@noescape is the default and is deprecated}} {{47-57=}}
 
 
+func takesArray(_ fns: [() -> Int]) {
+  doesEscape(fns[0]) // Okay - array-of-function parameters are escaping
+}
+
+func takesVariadic(_ fns: () -> Int...) {
+  doesEscape(fns[0]) // Okay - variadic-of-function parameters are escaping
+}
+
 func takesNoEscapeClosure(_ fn : () -> Int) {
   // expected-note@-1{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
   // expected-note@-2{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
   // expected-note@-3{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
   // expected-note@-4{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
+  // expected-note@-5{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
+  // expected-note@-6{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
+  // expected-note@-7{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
+  // expected-note@-8{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
+  // expected-note@-9{{parameter 'fn' is implicitly non-escaping}} {{34-34=@escaping }}
   takesNoEscapeClosure { 4 }  // ok
 
   _ = fn()  // ok
@@ -37,6 +50,13 @@ func takesNoEscapeClosure(_ fn : () -> Int) {
   doesEscape(fn)                   // expected-error {{passing non-escaping parameter 'fn' to function expecting an @escaping closure}}
   takesGenericClosure(4, fn)       // ok
   takesGenericClosure(4) { fn() }  // ok.
+
+  _ = [fn] // expected-error {{non-escaping parameter 'fn' may only be called}}
+  _ = [doesEscape(fn)] // expected-error {{'(() -> Int) -> ()' is not convertible to '(@escaping () -> Int) -> ()'}}
+  _ = [1 : fn] // expected-error {{non-escaping parameter 'fn' may only be called}}
+  _ = [1 : doesEscape(fn)] // expected-error {{passing non-escaping parameter 'fn' to function expecting an @escaping closure}}
+  _ = "\(doesEscape(fn))" // expected-error {{passing non-escaping parameter 'fn' to function expecting an @escaping closure}}
+  _ = "\(takesArray([fn]))" // expected-error {{using non-escaping parameter 'fn' in a context expecting an @escaping closure}}
 }
 
 class SomeClass {
@@ -340,4 +360,3 @@ func noescapeD_noescapeT(@noescape f: @noescape () -> Bool) {} // expected-error
 
 func autoclosureD_noescapeT(@autoclosure f: @noescape () -> Bool) {} // expected-error {{attribute can only be applied to types, not declarations}}
  // expected-warning@-1{{@noescape is the default and is deprecated}} {{45-55=}}
-