REVERTME: Temporarily make vars in refutable patterns a warning

Revert "Make function parameters and refutable patterns always
immutable"

This reverts commit 8f2fbdc.

Once we have finally merged master into the Swift 2.2 branch to be, we
should revert this commit to turn the errors back on for Swift 3.0.

Author: bitjammer

include/swift/AST/DiagnosticsParse.def

@@ -641,10 +641,8 @@ ERROR(untyped_pattern_ellipsis,pattern_parsing,none,
       "'...' cannot be applied to a subpattern which is not explicitly typed", ())
 ERROR(non_func_decl_pattern_init,pattern_parsing,none,
       "default argument is only permitted for a non-curried function parameter",())
-ERROR(var_not_allowed_in_pattern,pattern_parsing, none,
-      "Use of 'var' binding here is not allowed", ())
-WARNING(let_on_param_is_redundant,pattern_parsing, none,
-      "'let' keyword is unnecessary; function parameters are immutable by default", (unsigned))
+WARNING(var_not_allowed_in_pattern,pattern_parsing, none,
+      "Use of '%select{var|let}0' binding here is deprecated and will be removed in a future version of Swift", (unsigned))
 ERROR(var_pattern_in_var,pattern_parsing,none,
       "'%select{var|let}0' cannot appear nested inside another 'var' or "
       "'let' pattern", (unsigned))

lib/Parse/ParsePattern.cpp

@@ -179,15 +179,15 @@ Parser::parseParameterClause(SourceLoc &leftParenLoc,
       param.LetVarInOutLoc = consumeToken();
       param.SpecifierKind = ParsedParameter::InOut;
     } else if (Tok.is(tok::kw_let)) {
-      diagnose(Tok.getLoc(), diag::let_on_param_is_redundant,
+      diagnose(Tok.getLoc(), diag::var_not_allowed_in_pattern,
                Tok.is(tok::kw_let)).fixItRemove(Tok.getLoc());
       param.LetVarInOutLoc = consumeToken();
       param.SpecifierKind = ParsedParameter::Let;
     } else if (Tok.is(tok::kw_var)) {
-      diagnose(Tok.getLoc(), diag::var_not_allowed_in_pattern)
-        .fixItRemove(Tok.getLoc());
+      diagnose(Tok.getLoc(), diag::var_not_allowed_in_pattern,
+               Tok.is(tok::kw_let)).fixItRemove(Tok.getLoc());
       param.LetVarInOutLoc = consumeToken();
-      param.SpecifierKind = ParsedParameter::Let;
+      param.SpecifierKind = ParsedParameter::Var;
     }
 
     // Redundant specifiers are fairly common, recognize, reject, and recover
@@ -855,8 +855,8 @@ ParserResult<Pattern> Parser::parsePattern() {
     } else {
       // In an always immutable context, `var` is not allowed.
       if (alwaysImmutable)
-        diagnose(varLoc, diag::var_not_allowed_in_pattern)
-          .fixItRemove(varLoc);
+        diagnose(varLoc, diag::var_not_allowed_in_pattern, isLetKeyword)
+        .fixItRemove(varLoc);
     }
 
     // In our recursive parse, remember that we're in a var/let pattern.
@@ -1067,7 +1067,7 @@ ParserResult<Pattern> Parser::parseMatchingPatternAsLetOrVar(bool isLet,
     diagnose(varLoc, diag::let_pattern_in_immutable_context);
 
   if (!isLet && InVarOrLetPattern == IVOLP_AlwaysImmutable)
-    diagnose(varLoc, diag::var_not_allowed_in_pattern)
+    diagnose(varLoc, diag::var_not_allowed_in_pattern, isLet)
       .fixItReplace(varLoc, "let");
 
   // In our recursive parse, remember that we're in a var/let pattern.

test/Constraints/patterns.swift

@@ -167,8 +167,8 @@ default: break
 
 // FIXME: rdar://problem/23378003
 // These will eventually become errors.
-for (var x) in 0...100 {} // expected-error {{Use of 'var' binding here is not allowed}} {{6-9=}}
-for var x in 0...100 {}  // expected-error {{Use of 'var' binding here is not allowed}} {{5-9=}}
+for (var x) in 0...100 {} // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{6-9=}}
+for var x in 0...100 {}  // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{5-9=}}
 
 for (let x) in 0...100 {} // expected-error {{'let' pattern is already in an immutable context}}
 

test/Parse/foreach.swift

@@ -35,5 +35,7 @@ func for_each(r: Range<Int>, iir: IntRange<Int>) {
   for i in r sum = sum + i; // expected-error{{expected '{' to start the body of for-each loop}}
   for let x in 0..<10 {} // expected-error {{'let' pattern is already in an immutable context}} {{7-11=}}
 
-  for var x in 0..<10 {} // expected-error {{Use of 'var' binding here is not allowed}} {{7-11=}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually become an error.
+  for var x in 0..<10 {} // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{7-11=}}
 }

test/Parse/matching_patterns.swift

@@ -32,9 +32,11 @@ case let (let b): // expected-error {{'let' cannot appear nested inside another
   print(b)
 
 // 'var' patterns (not allowed)
-case var a: // expected-error {{Use of 'var' binding here is not allowed}} {{6-9=let}}
+// FIXME: rdar://problem/23378003
+// This will eventually be an error.
+case var a: // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{6-9=let}}
   a += 1
-case var let a: // expected-error {{Use of 'var' binding here is not allowed}} {{6-9=let}}
+case var let a: // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{6-9=let}}
   // expected-error@-1 {{'let' cannot appear nested inside another 'var' or 'let' pattern}}
   print(a, terminator: "")
 

test/Parse/switch.swift

@@ -216,9 +216,9 @@ case (1, let b): // let bindings
 // var bindings are not allowed in cases.
 // FIXME: rdar://problem/23378003
 // This will eventually be an error.
-case (1, var b): // expected-error {{Use of 'var' binding here is not allowed}} {{10-13=let}}
+case (1, var b): // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{10-13=let}}
   ()
-case (var a, 2): // expected-error {{Use of 'var' binding here is not allowed}} {{7-10=let}}
+case (var a, 2): // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{7-10=let}}
   ()
 
 case (let a, 2), (1, let b): // expected-error {{'case' labels with multiple patterns cannot declare variables}}

test/Sema/immutability.swift

@@ -221,10 +221,10 @@ func test_mutability() {
 
 
 func test_arguments(a : Int,
-                    var b : Int, // expected-error {{Use of 'var' binding here is not allowed}} {{21-25=}}
-                    let c : Int) { // expected-warning {{'let' keyword is unnecessary; function parameters are immutable by default}} {{21-25=}}
+                    var b : Int, // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{21-25=}}
+                    let c : Int) {   // expected-warning {{Use of 'let' binding here is deprecated and will be removed in a future version of Swift}} {{21-25=}}
   a = 1  // expected-error {{cannot assign to value: 'a' is a 'let' constant}}
-  var b = 2  // ok.
+  b = 2  // ok.
   c = 3  // expected-error {{cannot assign to value: 'c' is a 'let' constant}}
 }
 

test/SourceKit/SourceDocInfo/cursor_info.swift

@@ -146,7 +146,7 @@ public class SubscriptCursorTest {
 
 // RUN: %sourcekitd-test -req=cursor -pos=28:24 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | FileCheck -check-prefix=CHECK12 %s
 // CHECK12: source.lang.swift.decl.var.local (28:23-28:27)
-// CHECK12: <Declaration>let arg1: <Type usr="s:Si">Int</Type></Declaration>
+// CHECK12: <Declaration>var arg1: <Type usr="s:Si">Int</Type></Declaration>
 
 // RUN: %sourcekitd-test -req=cursor -pos=31:7 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | FileCheck -check-prefix=CHECK13 %s
 // CHECK13: source.lang.swift.decl.function.free (31:6-31:37)

test/decl/func/functions.swift

@@ -121,10 +121,8 @@ func testObjCMethodCurry(a : ClassWithObjCMethod) -> (Int) -> () {
 }
 
 // We used to crash on this.
-func rdar16786220(var let c: Int) -> () { // expected-error {{Use of 'var' binding here is not allowed}} {{19-22=}} expected-error {{parameter may not have multiple 'inout', 'var', or 'let' specifiers}}
-  var c = c
+func rdar16786220(var let c: Int) -> () { // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{19-22=}} expected-error {{parameter may not have multiple 'inout', 'var', or 'let' specifiers}}
   c = 42
-  _ = c
 }
 
 
@@ -138,11 +136,9 @@ func !!!<T>(lhs: UnsafePointer<T>, rhs: UnsafePointer<T>) -> Bool { return false
 
 // <rdar://problem/16786168> Functions currently permit 'var inout' parameters
 func inout_inout_error(inout inout x : Int) {} // expected-error {{parameter may not have multiple 'inout', 'var', or 'let' specifiers}} {{30-36=}}
-// expected-error@+1 {{Use of 'var' binding here is not allowed}} {{22-25=}}
+// expected-warning@+1 {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{22-25=}}
 func var_inout_error(var inout x : Int) { // expected-error {{parameter may not have multiple 'inout', 'var', or 'let' specifiers}} {{26-32=}}
-  var x = x
   x = 2
-  _ = x
 }
 
 // Unnamed parameters require the name "_":

test/decl/var/usage.swift

@@ -12,13 +12,11 @@ func basicTests() -> Int {
   return y
 }
 
-// expected-error@+2 {{Use of 'var' binding here is not allowed}} {{41-45=}}
-// expected-error@+1 {{Use of 'var' binding here is not allowed}} {{54-58=}}
+// expected-warning@+2 {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{41-45=}}
+// expected-warning@+1 {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{54-58=}}
 func mutableParameter(a : Int, h : Int, var i : Int, var j: Int, 
-       var g : Int) -> Int { // expected-error {{Use of 'var' binding here is not allowed}} {{8-12=}}
-  // expected-error@+1 {{left side of mutating operator isn't mutable: 'g' is a 'let' constant}}
+       var g : Int) -> Int { // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{8-12=}}
   g += 1
-  // expected-error@+1 {{cannot pass immutable value as inout argument: 'i' is a 'let' constant}}
   swap(&i, &j)
   return i+g
 }
@@ -102,10 +100,9 @@ func testSubscript() -> [Int] {
 }
 
 
-func testTuple(var x : Int) -> Int { // expected-error {{Use of 'var' binding here is not allowed}} {{16-19=}}
+func testTuple(var x : Int) -> Int { // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{16-19=}}
   var y : Int  // Ok, stored by a tuple
 
-  // expected-error@+1 {{cannot assign to value: 'x' is a 'let' constant}}
   (x, y) = (1,2)
   return y
 }
@@ -166,9 +163,8 @@ protocol Fooable {
   mutating func mutFoo()
   func immutFoo()
 }
-func testOpenExistential(var x: Fooable, // expected-error {{Use of 'var' binding here is not allowed}} {{26-29=}}
+func testOpenExistential(var x: Fooable, // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{26-29=}}
                          y: Fooable) {
-  // expected-error@+1 {{cannot use mutating member on immutable value}}
   x.mutFoo()
   y.immutFoo()
 }
@@ -177,27 +173,35 @@ func testOpenExistential(var x: Fooable, // expected-error {{Use of 'var' bindin
 func couldThrow() throws {}
 
 func testFixitsInStatementsWithPatterns(a : Int?) {
-  if var b = a,    // expected-error {{Use of 'var' binding here is not allowed}} {{6-9=let}}
-      var b2 = a {  // expected-error {{Use of 'var' binding here is not allowed}} {{7-10=let}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually be an error.
+  if var b = a,    // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{6-9=let}}
+      var b2 = a {  // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{7-10=let}}
     b = 1
     b2 = 1
     _ = b
     _ = b2
   }
 
   var g = [1,2,3].generate()
-  while var x = g.next() { // expected-error {{Use of 'var' binding here is not allowed}} {{9-12=let}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually be an error.
+  while var x = g.next() { // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{9-12=let}}
     x = 0
     _ = x
   }
 
-  guard var y = Optional.Some(1) else { // expected-error {{Use of 'var' binding here is not allowed}} {{9-12=let}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually be an error.
+  guard var y = Optional.Some(1) else { // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{9-12=let}}
     return
   }
   y = 0
   _ = y
 
-  for var b in [42] {   // expected-error {{Use of 'var' binding here is not allowed}} {{7-11=}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually be an error.
+  for var b in [42] {   // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{7-11=}}
     b = 42
     _ = b
   }
@@ -208,14 +212,18 @@ func testFixitsInStatementsWithPatterns(a : Int?) {
 
   do {
     try couldThrow()
-  } catch var err {  // expected-error {{Use of 'var' binding here is not allowed}} {{11-14=let}}
+  // FIXME: rdar://problem/23378003
+  // This will eventually be an error.
+  } catch var err {  // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{11-14=let}}
     // expected-warning@-1 {{variable 'err' was never mutated; consider changing to 'let' constant}}
     _ = err
   }
 
   switch a {
-    case var b: // expected-error {{Use of 'var' binding here is not allowed}} {{10-13=let}}
-      // expected-warning@-1 {{was never mutated; consider changing to 'let' constant}}
+    // FIXME: rdar://problem/23378003
+    // This will eventually be an error.
+    case var b: // expected-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{10-13=let}}
+      // expected-warning@-1 {{variable 'b' was never mutated; consider changing to 'let' constant}}
       _ = b
   }
 }

test/expr/closure/closures.swift

@@ -158,8 +158,8 @@ class ExplicitSelfRequiredTest {
   }
 }
 
-// expected-error@+2 {{Use of 'var' binding here is not allowed}} {{57-60=}}
-// expected-warning@+1 {{'let' keyword is unnecessary; function parameters are immutable by default}} {{64-68=}}
+// expected-warning@+2 {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{57-60=}}
+// expected-warning@+1 {{Use of 'let' binding here is deprecated and will be removed in a future version of Swift}} {{64-68=}}
 var testClosureArgumentPatterns: (Int, Int) -> Int = { (var x, let y) in x+y+1 }
 
 class SomeClass {