Revert "REVERTME: Temporarily make vars in refutable patterns a warning"

This reverts commit b96e06d, making
vars in refutable patterns an error for Swift 3.

rdar://problem/23172698

Author: bitjammer

include/swift/AST/DiagnosticsParse.def

@@ -632,8 +632,10 @@ 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",())
-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_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))
 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

@@ -180,15 +180,15 @@ Parser::parseParameterClause(SourceLoc &leftParenLoc,
       param.LetVarInOutLoc = consumeToken();
       param.SpecifierKind = ParsedParameter::InOut;
     } else if (Tok.is(tok::kw_let)) {
-      diagnose(Tok.getLoc(), diag::var_not_allowed_in_pattern,
+      diagnose(Tok.getLoc(), diag::let_on_param_is_redundant,
                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,
-               Tok.is(tok::kw_let)).fixItRemove(Tok.getLoc());
+      diagnose(Tok.getLoc(), diag::var_not_allowed_in_pattern)
+        .fixItRemove(Tok.getLoc());
       param.LetVarInOutLoc = consumeToken();
-      param.SpecifierKind = ParsedParameter::Var;
+      param.SpecifierKind = ParsedParameter::Let;
     }
 
     // Redundant specifiers are fairly common, recognize, reject, and recover
@@ -773,8 +773,8 @@ ParserResult<Pattern> Parser::parsePattern() {
     } else {
       // In an always immutable context, `var` is not allowed.
       if (alwaysImmutable)
-        diagnose(varLoc, diag::var_not_allowed_in_pattern, isLetKeyword)
-        .fixItRemove(varLoc);
+        diagnose(varLoc, diag::var_not_allowed_in_pattern)
+          .fixItRemove(varLoc);
     }
 
     // In our recursive parse, remember that we're in a var/let pattern.
@@ -978,7 +978,7 @@ 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, isLet)
+    diagnose(varLoc, diag::var_not_allowed_in_pattern)
       .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-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 (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 (let x) in 0...100 {} // expected-error {{'let' pattern is already in an immutable context}}
 

test/FixCode/fixits-apply.swift.result

@@ -38,7 +38,7 @@ func foo() -> Int {
   }
 }
 
-func goo(var e : ErrorType) {}
+func goo(e : ErrorType) {}
 
 struct Test1 : OptionSetType {
   init(rawValue: Int) {}

test/Parse/foreach.swift

@@ -35,7 +35,5 @@ 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=}}
 
-  // 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=}}
+  for var x in 0..<10 {} // expected-error {{Use of 'var' binding here is not allowed}} {{7-11=}}
 }

test/Parse/matching_patterns.swift

@@ -32,11 +32,9 @@ case let (let b): // expected-error {{'let' cannot appear nested inside another
   print(b)
 
 // 'var' patterns (not allowed)
-// 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}}
+case var a: // expected-error {{Use of 'var' binding here is not allowed}} {{6-9=let}}
   a += 1
-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}}
+case var let a: // expected-error {{Use of 'var' binding here is not allowed}} {{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-warning {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{10-13=let}}
+case (1, var b): // expected-error {{Use of 'var' binding here is not allowed}} {{10-13=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 (var a, 2): // expected-error {{Use of 'var' binding here is not allowed}} {{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-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=}}
+                    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=}}
   a = 1  // expected-error {{cannot assign to value: 'a' is a 'let' constant}}
-  b = 2  // ok.
+  var 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>var arg1: <Type usr="s:Si">Int</Type></Declaration>
+// CHECK12: <Declaration>let 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

@@ -121,8 +121,10 @@ func testObjCMethodCurry(a : ClassWithObjCMethod) -> (Int) -> () {
 }
 
 // We used to crash on this.
-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}}
+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
   c = 42
+  _ = c
 }
 
 
@@ -136,9 +138,11 @@ 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-warning@+1 {{Use of 'var' binding here is deprecated and will be removed in a future version of Swift}} {{22-25=}}
+// expected-error@+1 {{Use of 'var' binding here is not allowed}} {{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

@@ -12,11 +12,13 @@ func basicTests() -> Int {
   return y
 }
 
-// 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=}}
+// 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=}}
 func mutableParameter(a : Int, h : Int, var i : Int, var j: Int, 
-       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=}}
+       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}}
   g += 1
+  // expected-error@+1 {{cannot pass immutable value as inout argument: 'i' is a 'let' constant}}
   swap(&i, &j)
   return i+g
 }
@@ -100,9 +102,10 @@ func testSubscript() -> [Int] {
 }
 
 
-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=}}
+func testTuple(var x : Int) -> Int { // expected-error {{Use of 'var' binding here is not allowed}} {{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
 }
@@ -163,8 +166,9 @@ protocol Fooable {
   mutating func mutFoo()
   func immutFoo()
 }
-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=}}
+func testOpenExistential(var x: Fooable, // expected-error {{Use of 'var' binding here is not allowed}} {{26-29=}}
                          y: Fooable) {
+  // expected-error@+1 {{cannot use mutating member on immutable value}}
   x.mutFoo()
   y.immutFoo()
 }
@@ -173,35 +177,27 @@ func testOpenExistential(var x: Fooable, // expected-warning {{Use of 'var' bind
 func couldThrow() throws {}
 
 func testFixitsInStatementsWithPatterns(a : Int?) {
-  // 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}}
+  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}}
     b = 1
     b2 = 1
     _ = b
     _ = b2
   }
 
   var g = [1,2,3].generate()
-  // 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}}
+  while var x = g.next() { // expected-error {{Use of 'var' binding here is not allowed}} {{9-12=let}}
     x = 0
     _ = x
   }
 
-  // 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}}
+  guard var y = Optional.Some(1) else { // expected-error {{Use of 'var' binding here is not allowed}} {{9-12=let}}
     return
   }
   y = 0
   _ = y
 
-  // 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=}}
+  for var b in [42] {   // expected-error {{Use of 'var' binding here is not allowed}} {{7-11=}}
     b = 42
     _ = b
   }
@@ -212,18 +208,14 @@ func testFixitsInStatementsWithPatterns(a : Int?) {
 
   do {
     try couldThrow()
-  // 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}}
+  } catch var err {  // expected-error {{Use of 'var' binding here is not allowed}} {{11-14=let}}
     // expected-warning@-1 {{variable 'err' was never mutated; consider changing to 'let' constant}}
     _ = err
   }
 
   switch a {
-    // 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}}
+    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}}
       _ = b
   }
 }

test/expr/closure/closures.swift

@@ -157,8 +157,8 @@ class ExplicitSelfRequiredTest {
   }
 }
 
-// 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=}}
+// 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=}}
 var testClosureArgumentPatterns: (Int, Int) -> Int = { (var x, let y) in x+y+1 }
 
 class SomeClass {