Fix a NULL pointer dereference and update test cases.

Author: DougGregor

lib/Sema/CSApply.cpp

@@ -5786,7 +5786,7 @@ Expr *ExprRewriter::coerceCallArguments(
   // Warn if there was a recent change in trailing closure binding semantics
   // that might have lead to a silent change in behavior.
   maybeWarnAboutTrailingClosureBindingChange(
-      callee, apply->getFn(), arg, args, params, paramInfo,
+      callee, apply ? apply->getFn() : nullptr, arg, args, params, paramInfo,
       unlabeledTrailingClosureIndex, parameterBindings);
 
   SourceLoc lParenLoc, rParenLoc;

test/Parse/multiple_trailing_closures.swift

@@ -68,12 +68,14 @@ func bar(_ s: S) {
   }
 }
 
-func multiple_trailing_with_defaults(
+func multiple_trailing_with_defaults( // expected-note{{contains defaulted closure parameters 'animations' and 'completion'}}
   duration: Int,
   animations: (() -> Void)? = nil,
   completion: (() -> Void)? = nil) {}
 
-multiple_trailing_with_defaults(duration: 42) {}
+multiple_trailing_with_defaults(duration: 42) {} // expected-warning{{unlabeled trailing closure argument matches}}
+// expected-note@-1{{'completion' to retain}}
+// expected-note@-2{{'animations' to silence this}}
 
 multiple_trailing_with_defaults(duration: 42) {} completion: {}
 

test/expr/closure/trailing.swift

@@ -5,7 +5,7 @@ func takeFunc(_ f: (Int) -> Int) -> Int {}
 func takeValueAndFunc(_ value: Int, _ f: (Int) -> Int) {}
 func takeTwoFuncs(_ f: (Int) -> Int, _ g: (Int) -> Int) {}
 func takeFuncWithDefault(f : ((Int) -> Int)? = nil) {}
-func takeTwoFuncsWithDefaults(f1 : ((Int) -> Int)? = nil, f2 : ((String) -> String)? = nil) {}
+func takeTwoFuncsWithDefaults(f1 : ((Int) -> Int)? = nil, f2 : ((String) -> String)? = nil) {} // expected-note{{contains defaulted closure parameters 'f1' and 'f2'}}
 
 struct X {
   func takeFunc(_ f: (Int) -> Int) {}
@@ -94,8 +94,6 @@ var c3 = C().map // expected-note{{callee is here}}
 func multiTrailingClosure(_ a : () -> (), b : () -> ()) {  // expected-note {{'multiTrailingClosure(_:b:)' declared here}}
   multiTrailingClosure({}) {} // ok
   multiTrailingClosure {} {}   // expected-error {{missing argument for parameter 'b' in call}} expected-error {{consecutive statements on a line must be separated by ';'}} {{26-26=;}} expected-error {{closure expression is unused}} expected-note{{did you mean to use a 'do' statement?}} {{27-27=do }}
-  
-  
 }
 
 func labeledArgumentAndTrailingClosure() {
@@ -108,7 +106,8 @@ func labeledArgumentAndTrailingClosure() {
 
   // Trailing closure binds to first parameter.
  takeTwoFuncsWithDefaults { "Hello, " + $0 } // expected-error{{cannot convert value of type 'String' to expected argument type 'Int'}}
-  takeTwoFuncsWithDefaults { $0 + 1 }
+  takeTwoFuncsWithDefaults { $0 + 1 } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
   takeTwoFuncsWithDefaults(f1: {$0 + 1 })
 }
 

test/expr/postfix/call/forward_trailing_closure.swift

@@ -1,6 +1,6 @@
 // RUN: %target-typecheck-verify-swift -disable-fuzzy-forward-scan-trailing-closure-matching
 
-func forwardMatch1(
+func forwardMatch1( // expected-note 5 {{contains defaulted}}
   a: Int = 0, b: Int = 17, closure1: (Int) -> Int = { $0 }, c: Int = 42,
   numbers: Int..., closure2: ((Double) -> Double)? = nil,
   closure3: (String) -> String = { $0 + "!" }
@@ -11,24 +11,29 @@ func testForwardMatch1(i: Int, d: Double, s: String) {
   forwardMatch1()
 
   // Matching closure1
-  forwardMatch1 { _ in i }
+  forwardMatch1 { _ in i } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
   forwardMatch1 { _ in i } closure2: { d + $0 }
   forwardMatch1 { _ in i } closure2: { d + $0 } closure3: { $0 + ", " + s + "!" }
   forwardMatch1 { _ in i } closure3: { $0 + ", " + s + "!" }
 
-  forwardMatch1(a: 5) { $0 + i }
+  forwardMatch1(a: 5) { $0 + i } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
   forwardMatch1(a: 5) { $0 + i } closure2: { d + $0 }
   forwardMatch1(a: 5) { $0 + i } closure2: { d + $0 } closure3: { $0 + ", " + s + "!" }
   forwardMatch1(a: 5) { $0 + i } closure3: { $0 + ", " + s + "!" }
 
-  forwardMatch1(b: 1) { $0 + i }
+  forwardMatch1(b: 1) { $0 + i } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
   forwardMatch1(b: 1) { $0 + i } closure2: { d + $0 }
   forwardMatch1(b: 1) { $0 + i } closure2: { d + $0 } closure3: { $0 + ", " + s + "!" }
   forwardMatch1(b: 1) { $0 + i } closure3: { $0 + ", " + s + "!" }
 
   // Matching closure2
-  forwardMatch1(closure1: { $0 + i }) { d + $0 }
-  forwardMatch1(closure1: { $0 + i }, numbers: 1, 2, 3) { d + $0 }
+  forwardMatch1(closure1: { $0 + i }) { d + $0 } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
+  forwardMatch1(closure1: { $0 + i }, numbers: 1, 2, 3) { d + $0 } // expected-warning{{rather than}}
+  // expected-note@-1 2{{label the argument}}
   forwardMatch1(closure1: { $0 + i }, numbers: 1, 2, 3) { d + $0 } closure3: { $0 + ", " + s + "!" }
 
   // Matching closure3