Fix <rdar://problem/22602657> better diagnostics for closures w/o "in" clause

improving the message when too-many arguments are used in a closureexpr with
a known contextual type.

Author: lattner

include/swift/AST/DiagnosticsSema.def

@@ -2053,8 +2053,8 @@ NOTE(remove_label_for_tuple_pattern,sema_tcp,none,
 ERROR(tuple_pattern_in_non_tuple_context,sema_tcp,none,
       "tuple pattern cannot match values of the non-tuple type %0", (Type))
 ERROR(closure_argument_list_tuple,sema_tcp,none,
-      "contextual type for closure argument list expects %0 argument%s0, "
-      "but %1 were specified", (unsigned, unsigned))
+      "contextual closure type %0 expects %1 argument%s1, "
+      "but %2 were used in closure body", (Type, unsigned, unsigned))
 ERROR(closure_argument_list_missing,sema_tcp,none,
       "contextual type for closure argument list expects %0 argument%s0, "
       "which cannot be implicitly ignored", (unsigned))

lib/Sema/CSDiag.cpp

@@ -4043,8 +4043,12 @@ bool FailureDiagnosis::visitClosureExpr(ClosureExpr *CE) {
         return true;
       }
 
+      // Okay, the wrong number of arguments was used, complain about that.
+      // Before doing so, strip attributes off the function type so that they
+      // don't confuse the issue.
+      fnType = FunctionType::get(fnType->getInput(), fnType->getResult());
       diagnose(params->getStartLoc(), diag::closure_argument_list_tuple,
-               inferredArgCount, actualArgCount);
+               fnType, inferredArgCount, actualArgCount);
       return true;
     }
 

test/Constraints/closures.swift

@@ -115,24 +115,24 @@ var _: (Int)-> Int = { 0 }
 // expected-error @+1 {{contextual type for closure argument list expects 2 arguments, which cannot be implicitly ignored}} {{28-28=_,_ in }}
 var _: (Int, Int)-> Int = {0}
 
-// expected-error @+1 {{contextual type for closure argument list expects 2 arguments, but 3 were specified}}
+// expected-error @+1 {{contextual closure type '(Int, Int) -> Int' expects 2 arguments, but 3 were used in closure body}}
 var _: (Int,Int)-> Int = {$0+$1+$2}
 
-// expected-error @+1 {{contextual type for closure argument list expects 3 arguments, but 2 were specified}}
+// expected-error @+1 {{contextual closure type '(Int, Int, Int) -> Int' expects 3 arguments, but 2 were used in closure body}}
 var _: (Int, Int, Int)-> Int = {$0+$1}
 
 
 var _: ()-> Int = {a in 0}
 
-// expected-error @+1 {{contextual type for closure argument list expects 1 argument, but 2 were specified}}
+// expected-error @+1 {{contextual closure type '(Int) -> Int' expects 1 argument, but 2 were used in closure body}}
 var _: (Int)-> Int = {a,b in 0}
 
-// expected-error @+1 {{contextual type for closure argument list expects 1 argument, but 3 were specified}}
+// expected-error @+1 {{contextual closure type '(Int) -> Int' expects 1 argument, but 3 were used in closure body}}
 var _: (Int)-> Int = {a,b,c in 0}
 
 var _: (Int, Int)-> Int = {a in 0}
 
-// expected-error @+1 {{contextual type for closure argument list expects 3 arguments, but 2 were specified}}
+// expected-error @+1 {{contextual closure type '(Int, Int, Int) -> Int' expects 3 arguments, but 2 were used in closure body}}
 var _: (Int, Int, Int)-> Int = {a, b in a+b}
 
 // <rdar://problem/15998821> Fail to infer types for closure that takes an inout argument
@@ -157,3 +157,8 @@ func r15998821() {
   let g = { x in x = 3 }
   take_closure(g)
 }
+
+// <rdar://problem/22602657> better diagnostics for closures w/o "in" clause
+var _: (Int,Int)-> Int = {$0+$1+$2}  // expected-error {{contextual closure type '(Int, Int) -> Int' expects 2 arguments, but 3 were used in closure body}}
+
+

test/Constraints/diagnostics.swift

@@ -412,7 +412,7 @@ func f20371273() {
 func rdar21078316() {
   var foo : [String : String]?
   var bar : [(String, String)]?
-  bar = foo.map { ($0, $1) }  // expected-error {{contextual type for closure argument list expects 1 argument, but 2 were specified}}
+  bar = foo.map { ($0, $1) }  // expected-error {{contextual closure type '([String : String]) -> [(String, String)]' expects 1 argument, but 2 were used in closure body}}
 }