Remove requirement that the pattern in a `for` starts with `var`. (#5685)

This requirement was removed by proposal #1885.

toolchain/diagnostics/diagnostic_kind.def

@@ -91,7 +91,6 @@ CARBON_DIAGNOSTIC_KIND(ExpectedExprSemi)
 CARBON_DIAGNOSTIC_KIND(ExpectedStatementSemi)
 CARBON_DIAGNOSTIC_KIND(ExpectedStructLiteralField)
 CARBON_DIAGNOSTIC_KIND(ExpectedVarAfterReturned)
-CARBON_DIAGNOSTIC_KIND(ExpectedVariableDecl)
 CARBON_DIAGNOSTIC_KIND(ExpectedChoiceDefinition)
 CARBON_DIAGNOSTIC_KIND(ExpectedChoiceAlternativeName)
 CARBON_DIAGNOSTIC_KIND(NestedVar)

toolchain/parse/handle_statement.cpp

@@ -112,29 +112,44 @@ auto HandleStatementForHeader(Context& context) -> void {
   if (open_paren) {
     state.token = *open_paren;
   }
+
   state.kind = StateKind::StatementForHeaderIn;
+  context.PushState(state);
+  context.PushState(StateKind::Pattern);
+}
 
-  if (context.PositionIs(Lex::TokenKind::Var)) {
-    context.PushState(state);
-    context.PushState(StateKind::VarAsFor);
-    context.AddLeafNode(NodeKind::VariableIntroducer, context.Consume());
-  } else {
-    CARBON_DIAGNOSTIC(ExpectedVariableDecl, Error,
-                      "expected `var` declaration");
-    context.emitter().Emit(*context.position(), ExpectedVariableDecl);
+auto HandleStatementForHeaderIn(Context& context) -> void {
+  auto state = context.PopState();
 
-    if (auto next_in = context.FindNextOf({Lex::TokenKind::In})) {
-      context.SkipTo(*next_in);
-      context.ConsumeAndDiscard();
-    }
+  auto end_token = state.token;
+  if (context.PositionIs(Lex::TokenKind::In)) {
+    end_token = context.Consume();
+  } else if (context.PositionIs(Lex::TokenKind::Colon)) {
+    CARBON_DIAGNOSTIC(ExpectedInNotColon, Error,
+                      "`:` should be replaced by `in`");
+    context.emitter().Emit(*context.position(), ExpectedInNotColon);
+    state.has_error = true;
+    end_token = context.Consume();
+  } else if (!state.has_error) {
+    CARBON_DIAGNOSTIC(ExpectedIn, Error, "expected `in` after loop pattern");
+    context.emitter().Emit(*context.position(), ExpectedIn);
     state.has_error = true;
-    context.PushState(state);
   }
-}
 
-auto HandleStatementForHeaderIn(Context& context) -> void {
-  auto state = context.PopState();
+  context.AddNode(NodeKind::ForIn, end_token, state.has_error);
+
   context.PushState(state, StateKind::StatementForHeaderFinish);
+
+  // If we had a parse error, try to skip to the closing paren rather than
+  // parsing an expression.
+  if (state.has_error) {
+    auto open_token = context.state_stack().back().token;
+    if (context.tokens().GetKind(open_token).is_opening_symbol()) {
+      context.SkipTo(context.tokens().GetMatchedClosingToken(open_token));
+      return;
+    }
+  }
+
   context.PushState(StateKind::Expr);
 }
 

toolchain/parse/handle_var.cpp

@@ -50,15 +50,6 @@ auto HandleVarAsReturned(Context& context) -> void {
   HandleVar(context, StateKind::VarFinishAsRegular, returned_token);
 }
 
-auto HandleVarAsFor(Context& context) -> void {
-  auto state = context.PopState();
-
-  // The finished variable declaration will start at the `var`.
-  context.PushState(state, StateKind::VarFinishAsFor);
-
-  context.PushState(StateKind::Pattern);
-}
-
 auto HandleFieldDecl(Context& context) -> void {
   auto state = context.PopState();
 
@@ -141,30 +132,6 @@ auto HandleVarFinishAsField(Context& context) -> void {
   HandleVarFinish(context, NodeKind::FieldDecl);
 }
 
-auto HandleVarFinishAsFor(Context& context) -> void {
-  auto state = context.PopState();
-
-  context.AddNode(NodeKind::VariablePattern, state.token, state.has_error);
-
-  auto end_token = state.token;
-  if (context.PositionIs(Lex::TokenKind::In)) {
-    end_token = context.Consume();
-  } else if (context.PositionIs(Lex::TokenKind::Colon)) {
-    CARBON_DIAGNOSTIC(ExpectedInNotColon, Error,
-                      "`:` should be replaced by `in`");
-    context.emitter().Emit(*context.position(), ExpectedInNotColon);
-    state.has_error = true;
-    end_token = context.Consume();
-  } else {
-    CARBON_DIAGNOSTIC(ExpectedIn, Error,
-                      "expected `in` after loop `var` declaration");
-    context.emitter().Emit(*context.position(), ExpectedIn);
-    state.has_error = true;
-  }
-
-  context.AddNode(NodeKind::ForIn, end_token, state.has_error);
-}
-
 auto HandleVariablePattern(Context& context) -> void {
   auto state = context.PopState();
   if (state.in_var_pattern) {

toolchain/parse/state.def

@@ -1116,30 +1116,25 @@ CARBON_PARSE_STATE(StatementBreakFinish)
 //   (state done)
 CARBON_PARSE_STATE(StatementContinueFinish)
 
-// Handles `for` processing of `(var`, proceeding to a binding pattern before
-// continuing.
+// Handles `for` processing of `(`, proceeding to a pattern before continuing.
 //
-// for ( var ... )
+// for ( ... )
 //     ^
-//   1. VarAsFor
-//   2. StatementForHeaderIn
-//
-// for ( ???
-//     ^
-// for ( ??? in ...
-//     ^~~~~~~~
-// for ??? in ...
-//     ^~~~~~
 // for ???
 //    ^
-//   1. StatementForHeaderIn
+//   1. Pattern
+//   2. StatementForHeaderIn
 CARBON_PARSE_STATE(StatementForHeader)
 
 // Handles `for` processing of `in`, proceeding to an expression before
 // continuing.
 //
 // for ( ... in ... )
-//             ^
+//           ^~
+// for ( ... : ... )
+//           ^
+// for ( ... ??? )
+//          ^
 //   1. Expr
 //   2. StatementForHeaderFinish
 CARBON_PARSE_STATE(StatementForHeaderIn)
@@ -1372,11 +1367,6 @@ CARBON_PARSE_STATE(ImplBeforeAs)
 //   2. VarAfterPatternAsVar
 //   3. VarFinishAsRegular
 //
-// var ...             (variant is For)
-//    ^
-//   1. Pattern
-//   2. VarFinishAsFor
-//
 // returned var ...    (variant is Returned)
 // ^~~~~~~~~~~~
 //   1. Pattern
@@ -1386,7 +1376,7 @@ CARBON_PARSE_STATE(ImplBeforeAs)
 // returned ??? ;      (variant is Returned)
 // ^~~~~~~~~~~~~~
 //   (state done)
-CARBON_PARSE_STATE_VARIANTS3(Var, Regular, Returned, For)
+CARBON_PARSE_STATE_VARIANTS2(Var, Regular, Returned)
 
 // Handles `var` after the pattern, either followed by an initializer or the
 // semicolon.
@@ -1404,18 +1394,12 @@ CARBON_PARSE_STATE_VARIANTS2(VarAfterPattern, Var, Field)
 
 // Handles `var` parsing at the end.
 //
-// var ... ;        (variant is Regular or Field)
+// var ... ;
 //         ^
-// var ... ??? ;    (variant is Regular or Field)
+// var ... ??? ;
 //         ^~~~~
 //   (state done)
-//
-// var ... in       (variant is For)
-//         ^~
-// var ... :        (variant is For, invalid)
-//         ^
-//   (state done)
-CARBON_PARSE_STATE_VARIANTS3(VarFinish, Regular, For, Field)
+CARBON_PARSE_STATE_VARIANTS2(VarFinish, Regular, Field)
 
 // Handles the beginning of a field declaration (`var` in a class context).
 //

toolchain/parse/testdata/for/fail_colon_instead_of_in.carbon

@@ -27,14 +27,12 @@ fn foo() {
 // CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:             {kind: 'VariableIntroducer', text: 'var'},
 // CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
 // CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
-// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:               {kind: 'VarBindingPattern', text: ':', subtree_size: 3},
 // CHECK:STDOUT:             {kind: 'VariablePattern', text: 'var', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ForIn', text: ':', has_error: yes, subtree_size: 6},
-// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 9},
+// CHECK:STDOUT:           {kind: 'ForIn', text: ':', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', has_error: yes, subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
 // CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
 // CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
@@ -42,7 +40,7 @@ fn foo() {
 // CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
 // CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
 // CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 23},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 15},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 21},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/fail_missing_cond.carbon

@@ -13,7 +13,7 @@ fn F() {
   // CHECK:STDERR:   for {
   // CHECK:STDERR:       ^
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_missing_cond.carbon:[[@LINE+4]]:7: error: expected `var` declaration [ExpectedVariableDecl]
+  // CHECK:STDERR: fail_missing_cond.carbon:[[@LINE+4]]:7: error: expected name in binding pattern [ExpectedBindingPattern]
   // CHECK:STDERR:   for {
   // CHECK:STDERR:       ^
   // CHECK:STDERR:
@@ -38,14 +38,18 @@ fn F() {
 // CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: 'for', has_error: yes},
+// CHECK:STDOUT:               {kind: 'IdentifierNameNotBeforeParams', text: '{', has_error: yes},
+// CHECK:STDOUT:               {kind: 'InvalidParse', text: '{', has_error: yes},
+// CHECK:STDOUT:             {kind: 'LetBindingPattern', text: '{', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'for', has_error: yes, subtree_size: 4},
 // CHECK:STDOUT:             {kind: 'StructLiteralStart', text: '{'},
 // CHECK:STDOUT:           {kind: 'StructLiteral', text: '}', subtree_size: 2},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: 'for', has_error: yes, subtree_size: 4},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: 'for', has_error: yes, subtree_size: 8},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '}', has_error: yes},
 // CHECK:STDOUT:             {kind: 'InvalidParse', text: '}', has_error: yes},
 // CHECK:STDOUT:           {kind: 'ExprStatement', text: '}', has_error: yes, subtree_size: 2},
 // CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', has_error: yes, subtree_size: 4},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 9},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 15},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 13},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 19},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/fail_missing_in.carbon

@@ -9,7 +9,7 @@
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/for/fail_missing_in.carbon
 
 fn foo() {
-  // CHECK:STDERR: fail_missing_in.carbon:[[@LINE+4]]:19: error: expected `in` after loop `var` declaration [ExpectedIn]
+  // CHECK:STDERR: fail_missing_in.carbon:[[@LINE+4]]:19: error: expected `in` after loop pattern [ExpectedIn]
   // CHECK:STDERR:   for (var x: i32 y) {
   // CHECK:STDERR:                   ^
   // CHECK:STDERR:
@@ -27,14 +27,12 @@ fn foo() {
 // CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:             {kind: 'VariableIntroducer', text: 'var'},
 // CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
 // CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
-// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:               {kind: 'VarBindingPattern', text: ':', subtree_size: 3},
 // CHECK:STDOUT:             {kind: 'VariablePattern', text: 'var', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ForIn', text: 'var', has_error: yes, subtree_size: 6},
-// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 9},
+// CHECK:STDOUT:           {kind: 'ForIn', text: '(', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', has_error: yes, subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
 // CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
 // CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
@@ -42,7 +40,7 @@ fn foo() {
 // CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
 // CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
 // CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 23},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 15},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 21},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/fail_missing_var.carbon

@@ -1,42 +0,0 @@
-// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-// Exceptions. See /LICENSE for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// AUTOUPDATE
-// TIP: To test this file alone, run:
-// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/for/fail_missing_var.carbon
-// TIP: To dump output, run:
-// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/for/fail_missing_var.carbon
-
-fn foo() {
-  // CHECK:STDERR: fail_missing_var.carbon:[[@LINE+4]]:8: error: expected `var` declaration [ExpectedVariableDecl]
-  // CHECK:STDERR:   for (x: i32 in y) {
-  // CHECK:STDERR:        ^
-  // CHECK:STDERR:
-  for (x: i32 in y) {
-    Print(x);
-  }
-}
-
-// CHECK:STDOUT: - filename: fail_missing_var.carbon
-// CHECK:STDOUT:   parse_tree: [
-// CHECK:STDOUT:     {kind: 'FileStart', text: ''},
-// CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:         {kind: 'IdentifierNameBeforeParams', text: 'foo'},
-// CHECK:STDOUT:           {kind: 'ExplicitParamListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
-// CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
-// CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', has_error: yes, subtree_size: 3},
-// CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
-// CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
-// CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
-// CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'x'},
-// CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
-// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 11},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
-// CHECK:STDOUT:   ]

toolchain/parse/testdata/for/fail_returned_var.carbon

@@ -9,8 +9,7 @@
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/for/fail_returned_var.carbon
 
 fn foo() -> i32 {
-  // TODO: Should we allow this?
-  // CHECK:STDERR: fail_returned_var.carbon:[[@LINE+4]]:8: error: expected `var` declaration [ExpectedVariableDecl]
+  // CHECK:STDERR: fail_returned_var.carbon:[[@LINE+4]]:8: error: expected name in binding pattern [ExpectedBindingPattern]
   // CHECK:STDERR:   for (returned var x: i32 in y) {
   // CHECK:STDERR:        ^~~~~~~~
   // CHECK:STDERR:
@@ -30,14 +29,17 @@ fn foo() -> i32 {
 // CHECK:STDOUT:         {kind: 'ReturnType', text: '->', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT:               {kind: 'IdentifierNameNotBeforeParams', text: 'returned', has_error: yes},
+// CHECK:STDOUT:               {kind: 'InvalidParse', text: 'returned', has_error: yes},
+// CHECK:STDOUT:             {kind: 'LetBindingPattern', text: 'returned', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT:           {kind: 'ForIn', text: '(', has_error: yes, subtree_size: 4},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', has_error: yes, subtree_size: 6},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
 // CHECK:STDOUT:             {kind: 'ReturnStatementStart', text: 'return'},
 // CHECK:STDOUT:             {kind: 'ReturnVarModifier', text: 'var'},
 // CHECK:STDOUT:           {kind: 'ReturnStatement', text: ';', subtree_size: 3},
 // CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 9},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 17},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 12},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 20},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/fail_square_brackets.carbon

@@ -13,7 +13,7 @@ fn F() {
   // CHECK:STDERR:   for [] {
   // CHECK:STDERR:       ^
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_square_brackets.carbon:[[@LINE+16]]:7: error: expected `var` declaration [ExpectedVariableDecl]
+  // CHECK:STDERR: fail_square_brackets.carbon:[[@LINE+16]]:7: error: expected name in binding pattern [ExpectedBindingPattern]
   // CHECK:STDERR:   for [] {
   // CHECK:STDERR:       ^
   // CHECK:STDERR:
@@ -42,13 +42,17 @@ fn F() {
 // CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: 'for', has_error: yes},
+// CHECK:STDOUT:               {kind: 'IdentifierNameNotBeforeParams', text: '[', has_error: yes},
+// CHECK:STDOUT:               {kind: 'InvalidParse', text: '[', has_error: yes},
+// CHECK:STDOUT:             {kind: 'LetBindingPattern', text: '[', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'for', has_error: yes, subtree_size: 4},
 // CHECK:STDOUT:           {kind: 'InvalidParse', text: '[', has_error: yes},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: 'for', has_error: yes, subtree_size: 3},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: 'for', has_error: yes, subtree_size: 7},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '[', has_error: yes},
 // CHECK:STDOUT:             {kind: 'InvalidParse', text: '[', has_error: yes},
 // CHECK:STDOUT:           {kind: 'ExprStatement', text: '}', has_error: yes, subtree_size: 2},
 // CHECK:STDOUT:         {kind: 'CodeBlock', text: '[', has_error: yes, subtree_size: 4},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 8},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 14},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 12},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/nested.carbon

@@ -25,24 +25,22 @@ fn foo() {
 // CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:             {kind: 'VariableIntroducer', text: 'var'},
 // CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'y'},
 // CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
-// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:               {kind: 'VarBindingPattern', text: ':', subtree_size: 3},
 // CHECK:STDOUT:             {kind: 'VariablePattern', text: 'var', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 6},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 5},
 // CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'x'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 9},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 8},
 // CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
 // CHECK:STDOUT:               {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:                 {kind: 'VariableIntroducer', text: 'var'},
 // CHECK:STDOUT:                     {kind: 'IdentifierNameNotBeforeParams', text: 'z'},
 // CHECK:STDOUT:                     {kind: 'IntTypeLiteral', text: 'i32'},
-// CHECK:STDOUT:                   {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:                   {kind: 'VarBindingPattern', text: ':', subtree_size: 3},
 // CHECK:STDOUT:                 {kind: 'VariablePattern', text: 'var', subtree_size: 4},
-// CHECK:STDOUT:               {kind: 'ForIn', text: 'in', subtree_size: 6},
+// CHECK:STDOUT:               {kind: 'ForIn', text: 'in', subtree_size: 5},
 // CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:             {kind: 'ForHeader', text: ')', subtree_size: 9},
+// CHECK:STDOUT:             {kind: 'ForHeader', text: ')', subtree_size: 8},
 // CHECK:STDOUT:               {kind: 'CodeBlockStart', text: '{'},
 // CHECK:STDOUT:                     {kind: 'IdentifierNameExpr', text: 'Print'},
 // CHECK:STDOUT:                   {kind: 'CallExprStart', text: '(', subtree_size: 2},
@@ -50,9 +48,9 @@ fn foo() {
 // CHECK:STDOUT:                 {kind: 'CallExpr', text: ')', subtree_size: 4},
 // CHECK:STDOUT:               {kind: 'ExprStatement', text: ';', subtree_size: 5},
 // CHECK:STDOUT:             {kind: 'CodeBlock', text: '}', subtree_size: 7},
-// CHECK:STDOUT:           {kind: 'ForStatement', text: 'for', subtree_size: 17},
-// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 19},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 29},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 35},
+// CHECK:STDOUT:           {kind: 'ForStatement', text: 'for', subtree_size: 16},
+// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 18},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 27},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 33},
 // CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT:   ]

toolchain/parse/testdata/for/pattern.carbon

@@ -0,0 +1,119 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/for/pattern.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/for/pattern.carbon
+
+// --- value.carbon
+
+fn foo() {
+  for (x: i32 in y) {
+    Print(x);
+  }
+}
+
+// --- var.carbon
+
+fn foo() {
+  for (var x: i32 in y) {
+    Print(x);
+  }
+}
+
+// --- tuple.carbon
+
+fn foo() {
+  for ((x: i32, y: i32) in z) {
+    Print(x);
+  }
+}
+
+// CHECK:STDOUT: - filename: value.carbon
+// CHECK:STDOUT:   parse_tree: [
+// CHECK:STDOUT:     {kind: 'FileStart', text: ''},
+// CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:         {kind: 'IdentifierNameBeforeParams', text: 'foo'},
+// CHECK:STDOUT:           {kind: 'ExplicitParamListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
+// CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
+// CHECK:STDOUT:               {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
+// CHECK:STDOUT:               {kind: 'IntTypeLiteral', text: 'i32'},
+// CHECK:STDOUT:             {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 7},
+// CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
+// CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
+// CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'x'},
+// CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 15},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 21},
+// CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT:   ]
+// CHECK:STDOUT: - filename: var.carbon
+// CHECK:STDOUT:   parse_tree: [
+// CHECK:STDOUT:     {kind: 'FileStart', text: ''},
+// CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:         {kind: 'IdentifierNameBeforeParams', text: 'foo'},
+// CHECK:STDOUT:           {kind: 'ExplicitParamListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
+// CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
+// CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
+// CHECK:STDOUT:               {kind: 'VarBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:             {kind: 'VariablePattern', text: 'var', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 5},
+// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 8},
+// CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
+// CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
+// CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'x'},
+// CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 16},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 22},
+// CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT:   ]
+// CHECK:STDOUT: - filename: tuple.carbon
+// CHECK:STDOUT:   parse_tree: [
+// CHECK:STDOUT:     {kind: 'FileStart', text: ''},
+// CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
+// CHECK:STDOUT:         {kind: 'IdentifierNameBeforeParams', text: 'foo'},
+// CHECK:STDOUT:           {kind: 'ExplicitParamListStart', text: '('},
+// CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
+// CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
+// CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
+// CHECK:STDOUT:               {kind: 'TuplePatternStart', text: '('},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
+// CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
+// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:               {kind: 'PatternListComma', text: ','},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'y'},
+// CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
+// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
+// CHECK:STDOUT:             {kind: 'TuplePattern', text: ')', subtree_size: 9},
+// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 10},
+// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'z'},
+// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 13},
+// CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
+// CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
+// CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
+// CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'x'},
+// CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
+// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
+// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 21},
+// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 27},
+// CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
+// CHECK:STDOUT:   ]

toolchain/parse/testdata/for/simple.carbon

@@ -1,44 +0,0 @@
-// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-// Exceptions. See /LICENSE for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// AUTOUPDATE
-// TIP: To test this file alone, run:
-// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/for/simple.carbon
-// TIP: To dump output, run:
-// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/for/simple.carbon
-
-fn foo() {
-  for (var x: i32 in y) {
-    Print(x);
-  }
-}
-
-// CHECK:STDOUT: - filename: simple.carbon
-// CHECK:STDOUT:   parse_tree: [
-// CHECK:STDOUT:     {kind: 'FileStart', text: ''},
-// CHECK:STDOUT:         {kind: 'FunctionIntroducer', text: 'fn'},
-// CHECK:STDOUT:         {kind: 'IdentifierNameBeforeParams', text: 'foo'},
-// CHECK:STDOUT:           {kind: 'ExplicitParamListStart', text: '('},
-// CHECK:STDOUT:         {kind: 'ExplicitParamList', text: ')', subtree_size: 2},
-// CHECK:STDOUT:       {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 5},
-// CHECK:STDOUT:           {kind: 'ForHeaderStart', text: '('},
-// CHECK:STDOUT:             {kind: 'VariableIntroducer', text: 'var'},
-// CHECK:STDOUT:                 {kind: 'IdentifierNameNotBeforeParams', text: 'x'},
-// CHECK:STDOUT:                 {kind: 'IntTypeLiteral', text: 'i32'},
-// CHECK:STDOUT:               {kind: 'LetBindingPattern', text: ':', subtree_size: 3},
-// CHECK:STDOUT:             {kind: 'VariablePattern', text: 'var', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ForIn', text: 'in', subtree_size: 6},
-// CHECK:STDOUT:           {kind: 'IdentifierNameExpr', text: 'y'},
-// CHECK:STDOUT:         {kind: 'ForHeader', text: ')', subtree_size: 9},
-// CHECK:STDOUT:           {kind: 'CodeBlockStart', text: '{'},
-// CHECK:STDOUT:                 {kind: 'IdentifierNameExpr', text: 'Print'},
-// CHECK:STDOUT:               {kind: 'CallExprStart', text: '(', subtree_size: 2},
-// CHECK:STDOUT:               {kind: 'IdentifierNameExpr', text: 'x'},
-// CHECK:STDOUT:             {kind: 'CallExpr', text: ')', subtree_size: 4},
-// CHECK:STDOUT:           {kind: 'ExprStatement', text: ';', subtree_size: 5},
-// CHECK:STDOUT:         {kind: 'CodeBlock', text: '}', subtree_size: 7},
-// CHECK:STDOUT:       {kind: 'ForStatement', text: 'for', subtree_size: 17},
-// CHECK:STDOUT:     {kind: 'FunctionDefinition', text: '}', subtree_size: 23},
-// CHECK:STDOUT:     {kind: 'FileEnd', text: ''},
-// CHECK:STDOUT:   ]

toolchain/parse/typed_nodes.h

@@ -675,17 +675,15 @@ struct ReturnStatement {
 using ForHeaderStart =
     LeafNode<NodeKind::ForHeaderStart, Lex::OpenParenTokenIndex>;
 
-// The `var ... in` portion of a `for` statement.
+// The `... in` portion of a `for` statement.
 struct ForIn {
-  static constexpr auto Kind = NodeKind::ForIn.Define(
-      {.bracketed_by = VariableIntroducer::Kind, .child_count = 2});
+  static constexpr auto Kind = NodeKind::ForIn.Define({.child_count = 1});
 
-  VariableIntroducerId introducer;
   AnyPatternId pattern;
   Lex::InTokenIndex token;
 };
 
-// The `for (var ... in ...)` portion of a `for` statement.
+// The `for (... in ...)` portion of a `for` statement.
 struct ForHeader {
   static constexpr auto Kind =
       NodeKind::ForHeader.Define({.bracketed_by = ForHeaderStart::Kind});

toolchain/parse/typed_nodes_test.cpp

@@ -132,7 +132,7 @@ TEST_F(TypedNodeTest, For) {
   auto for_var_pattern = tree.ExtractAs<VariablePattern>(for_var->pattern);
   ASSERT_TRUE(for_var_pattern.has_value());
   auto for_var_binding =
-      tree.ExtractAs<LetBindingPattern>(for_var_pattern->inner);
+      tree.ExtractAs<VarBindingPattern>(for_var_pattern->inner);
   ASSERT_TRUE(for_var_binding.has_value());
   auto for_var_name =
       tree.ExtractAs<IdentifierNameNotBeforeParams>(for_var_binding->name);