Revise error for incorrect subscript parameters.

We use subscripts for more than just indexes in Swift these days, so
the error message needs to be a bit more general.

Author: natecook1000

include/swift/AST/DiagnosticsSema.def

@@ -213,7 +213,7 @@ ERROR(cannot_apply_lvalue_binop_to_rvalue,none,
       "left side of mutating operator has immutable type %0", (Type))
 
 ERROR(cannot_subscript_with_index,none,
-      "cannot subscript a value of type %0 with an index of type %1",
+      "cannot subscript a value of type %0 with a value of type %1",
       (Type, Type))
 
 ERROR(cannot_subscript_base,none,

test/Constraints/diagnostics.swift

@@ -215,7 +215,7 @@ func r21459429(_ a : Int) {
 }
 
 
-// <rdar://problem/21362748> [WWDC Lab] QoI: cannot subscript a value of type '[Int]?' with an index of type 'Int'
+// <rdar://problem/21362748> [WWDC Lab] QoI: cannot subscript a value of type '[Int]?' with a value of type 'Int'
 struct StructWithOptionalArray {
   var array: [Int]?
 }

test/Constraints/subscript.swift

@@ -110,7 +110,7 @@ class C_r25601561 {
 // rdar://problem/31977679 - Misleading diagnostics when using subscript with incorrect argument
 
 func r31977679_1(_ properties: [String: String]) -> Any? {
-  return properties[0] // expected-error {{cannot subscript a value of type '[String : String]' with an index of type 'Int'}}
+  return properties[0] // expected-error {{cannot subscript a value of type '[String : String]' with a value of type 'Int'}}
 }
 
 func r31977679_2(_ properties: [String: String]) -> Any? {

test/decl/func/keyword-argument-defaults.swift

@@ -106,7 +106,7 @@ func testMethods(_ i: Int, x: Y) {
 
 func testSubscripts(_ i: Int, s: String, x: Y) {
   var i2 = x[i]
-  var i3 = x[x: i] // expected-error{{cannot subscript a value of type 'Y' with an index of type '(x: Int)'}}
+  var i3 = x[x: i] // expected-error{{cannot subscript a value of type 'Y' with a value of type '(x: Int)'}}
   // expected-note @-1 {{overloads for 'subscript' exist with these partially matching parameter lists: (Int), (y: String)}}
   var s2 = x[y: s]
   var s3 = x[s]  // expected-error{{cannot convert value of type 'String' to expected argument type 'Int'}}

test/decl/subscript/subscripting.swift

@@ -318,10 +318,10 @@ struct SubscriptTest2 {
 }
 
 func testSubscript1(_ s2 : SubscriptTest2) {
-  _ = s2["foo"] // expected-error {{cannot subscript a value of type 'SubscriptTest2' with an index of type 'String'}}
+  _ = s2["foo"] // expected-error {{cannot subscript a value of type 'SubscriptTest2' with a value of type 'String'}}
   // expected-note @-1 {{overloads for 'subscript' exist with these partially matching parameter lists: (String, Int), (String, String)}}
 
-  let a = s2["foo", 1.0] // expected-error {{cannot subscript a value of type 'SubscriptTest2' with an index of type '(String, Double)'}}
+  let a = s2["foo", 1.0] // expected-error {{cannot subscript a value of type 'SubscriptTest2' with a value of type '(String, Double)'}}
   // expected-note @-1 {{overloads for 'subscript' exist with these partially matching parameter lists: (String, Int), (String, String)}}
 
   _ = s2.subscript("hello", 6)

test/type/types.swift

@@ -19,7 +19,7 @@ var d3 : () -> Float = { 4 }
 var d4 : () -> Int = { d2 }  // expected-error{{function produces expected type 'Int'; did you mean to call it with '()'?}} {{26-26=()}}
 
 var e0 : [Int]
-e0[] // expected-error {{cannot subscript a value of type '[Int]' with an index of type '()'}}
+e0[] // expected-error {{cannot subscript a value of type '[Int]' with a value of type '()'}}
   // expected-note @-1 {{overloads for 'subscript' exist with these partially matching parameter lists: ((UnboundedRange_) -> ()), (Int), (R), (Range<Int>), (Range<Self.Index>)}}
 
 var f0 : [Float]