Properly handle subscripts when avoiding IUO-to-Any coercion warnings.

Ensure that we grab the decl from the subscript expression so that we
can check whether it returns an IUO.

Also add tests for subscripts and failable inits.

(cherry picked from commit 08f80ec)

Author: rudkx

lib/Sema/MiscDiagnostics.cpp

@@ -3728,6 +3728,13 @@ static void diagnoseUnintendedOptionalBehavior(TypeChecker &TC, const Expr *E,
         if (auto *call = dyn_cast<CallExpr>(E))
           E = call->getDirectCallee();
 
+        if (auto *subscript = dyn_cast<SubscriptExpr>(E)) {
+          if (subscript->hasDecl())
+            return subscript->getDecl().getDecl();
+
+          return nullptr;
+        }
+
         if (auto *memberRef = dyn_cast<MemberRefExpr>(E))
           return memberRef->getMember().getDecl();
         if (auto *declRef = dyn_cast<DeclRefExpr>(E))

test/ClangImporter/objc_parse.swift

@@ -247,27 +247,18 @@ func almostSubscriptableValueMismatch(_ as1: AlmostSubscriptable, a: A) {
 func almostSubscriptableKeyMismatch(_ bc: BadCollection, key: NSString) {
   // FIXME: We end up importing this as read-only due to the mismatch between
   // getter/setter element types.
-  var _ : Any = bc[key] // expected-warning {{expression implicitly coerced from 'Any?' to 'Any'}}
-  // expected-note@-1 {{force-unwrap the value to avoid this warning}}
-  // expected-note@-2 {{provide a default value to avoid this warning}}
-  // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}
+  var _ : Any = bc[key]
 }
 
 func almostSubscriptableKeyMismatchInherited(_ bc: BadCollectionChild,
                                              key: String) {
-  var value : Any = bc[key] // expected-warning {{expression implicitly coerced from 'Any?' to 'Any'}}
-  // expected-note@-1 {{force-unwrap the value to avoid this warning}}
-  // expected-note@-2 {{provide a default value to avoid this warning}}
-  // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}
+  var value : Any = bc[key]
   bc[key] = value // expected-error{{cannot assign through subscript: subscript is get-only}}
 }
 
 func almostSubscriptableKeyMismatchInherited(_ roc: ReadOnlyCollectionChild,
                                              key: String) {
-  var value : Any = roc[key] // expected-warning {{expression implicitly coerced from 'Any?' to 'Any'}}
-  // expected-note@-1 {{force-unwrap the value to avoid this warning}}
-  // expected-note@-2 {{provide a default value to avoid this warning}}
-  // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}
+  var value : Any = roc[key]
   roc[key] = value // expected-error{{cannot assign through subscript: subscript is get-only}}
 }
 

test/Sema/diag_unintended_optional_behavior.swift

@@ -87,6 +87,13 @@ class C {
   var b: Any?!
   func returningIUO() -> Int! { return a }
   func returningAny() -> Any { return a }
+
+  subscript(i: Int) -> Int! { return 0 }
+  subscript(i: Float) -> Any! { return 0 }
+}
+
+class D {
+  init!() {}
 }
 
 func returningIUO() -> Int! { return 1 }
@@ -96,6 +103,8 @@ func nowarnIUOToAnyCoercion(_ a: Int!, _ b: Any?!) {
   _ = takeAny(a, b)
   _ = takeAny(returningIUO(), C().returningIUO())
   _ = takeAny(C().a, C().b)
+  _ = takeAny(C()[0], C()[1.0])
+  _ = takeAny(D(), D())
 
   _ = takeAny(a as Any, b as Any)
 }

test/Sema/diag_unintended_optional_behavior_swift_5.swift

@@ -16,6 +16,13 @@ class C {
   // expected-note@-1 {{provide a default value to avoid this warning}}{{40-40= ?? <#default value#>}}
   // expected-note@-2 {{force-unwrap the value to avoid this warning}}{{40-40=!}}
   // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{40-40= as Any}}
+
+  subscript(i: Int) -> Int! { return 0 }
+  subscript(i: Float) -> Any! { return 0 }
+}
+
+class D {
+  init!() {}
 }
 
 func returningIUO() -> Int! { return 1 }
@@ -43,6 +50,22 @@ func warnIUOToAnyCoercion(_ a: Int!, _ b: Any?!) {
   // expected-warning@-4 {{expression implicitly coerced from 'Any??' to 'Any'}}
   // expected-note@-5 {{force-unwrap the value to avoid this warning}}{{27-27=!!}}
   // expected-note@-6 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{27-27= as Any}}
+  _ = takeAny(C()[0], C()[1.0]) // expected-warning {{expression implicitly coerced from 'Int?' to 'Any'}}
+  // expected-note@-1 {{provide a default value to avoid this warning}}{{21-21= ?? <#default value#>}}
+  // expected-note@-2 {{force-unwrap the value to avoid this warning}}{{21-21=!}}
+  // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{21-21= as Any}}
+  // expected-warning@-4 {{expression implicitly coerced from 'Any?' to 'Any'}}
+  // expected-note@-5 {{provide a default value to avoid this warning}}{{31-31= ?? <#default value#>}}
+  // expected-note@-6 {{force-unwrap the value to avoid this warning}}{{31-31=!}}
+  // expected-note@-7 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{31-31= as Any}}
+  _ = takeAny(D(), D()) // expected-warning {{expression implicitly coerced from 'D?' to 'Any'}}
+  // expected-note@-1 {{provide a default value to avoid this warning}}{{18-18= ?? <#default value#>}}
+  // expected-note@-2 {{force-unwrap the value to avoid this warning}}{{18-18=!}}
+  // expected-note@-3 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{18-18= as Any}}
+  // expected-warning@-4 {{expression implicitly coerced from 'D?' to 'Any'}}
+  // expected-note@-5 {{provide a default value to avoid this warning}}{{23-23= ?? <#default value#>}}
+  // expected-note@-6 {{force-unwrap the value to avoid this warning}}{{23-23=!}}
+  // expected-note@-7 {{explicitly cast to 'Any' with 'as Any' to silence this warning}}{{23-23= as Any}}
 
   _ = takeAny(a as Any, b as Any)
 }