std.zig.Ast: store lbrace and rbrace token in data of .error_set_decl

This makes the `.data` field the better choice over the `.main_token` for this tag.

Author: Techatrix

lib/compiler/reduce/Walk.zig

@@ -444,9 +444,7 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {
         },
 
         .error_set_decl => {
-            const error_token = ast.nodeMainToken(node);
-            const lbrace = error_token + 1;
-            const rbrace = ast.nodeData(node).token;
+            const lbrace, const rbrace = ast.nodeData(node).token_and_token;
 
             var i = lbrace + 1;
             while (i < rbrace) : (i += 1) {

lib/std/zig/Ast.zig

@@ -996,9 +996,8 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
         .unwrap_optional,
         .asm_simple,
         => return tree.nodeData(n).node_and_token[1] + end_offset,
-        .error_set_decl => return tree.nodeData(n).token + end_offset,
         .grouped_expression, .asm_input => return tree.nodeData(n).node_and_token[1] + end_offset,
-        .multiline_string_literal => return tree.nodeData(n).token_and_token[1] + end_offset,
+        .multiline_string_literal, .error_set_decl => return tree.nodeData(n).token_and_token[1] + end_offset,
         .asm_output => return tree.nodeData(n).opt_node_and_token[1] + end_offset,
         .error_value => return tree.nodeMainToken(n) + 2 + end_offset,
 
@@ -3758,7 +3757,9 @@ pub const Node = struct {
         builtin_call_comma,
         /// `error{a, b}`.
         ///
-        /// The `data` field is a `.token` to the '}'.
+        /// The `data` field is a `.token_and_token`:
+        ///   1. a `TokenIndex` to the `{` token.
+        ///   2. a `TokenIndex` to the `}` token.
         ///
         /// The `main_token` field is the `error`.
         error_set_decl,

lib/std/zig/AstGen.zig

@@ -5974,9 +5974,9 @@ fn errorSetDecl(gz: *GenZir, ri: ResultInfo, node: Ast.Node.Index) InnerError!Zi
         var idents: std.AutoHashMapUnmanaged(Zir.NullTerminatedString, Ast.TokenIndex) = .empty;
         defer idents.deinit(gpa);
 
-        const error_token = tree.nodeMainToken(node);
-        var tok_i = error_token + 2;
-        while (true) : (tok_i += 1) {
+        const lbrace, const rbrace = tree.nodeData(node).token_and_token;
+        for (lbrace + 1..rbrace) |i| {
+            const tok_i: Ast.TokenIndex = @intCast(i);
             switch (tree.tokenTag(tok_i)) {
                 .doc_comment, .comma => {},
                 .identifier => {
@@ -6003,7 +6003,6 @@ fn errorSetDecl(gz: *GenZir, ri: ResultInfo, node: Ast.Node.Index) InnerError!Zi
                     try astgen.extra.append(gpa, @intFromEnum(str_index));
                     fields_len += 1;
                 },
-                .r_brace => break,
                 else => unreachable,
             }
         }

lib/std/zig/Parse.zig

@@ -2763,7 +2763,12 @@ fn parsePrimaryTypeExpr(p: *Parse) !?Node.Index {
                 return try p.addNode(.{
                     .tag = .error_set_decl,
                     .main_token = error_token,
-                    .data = .{ .token = p.tok_i - 1 }, // rbrace
+                    .data = .{
+                        .token_and_token = .{
+                            error_token + 1, // lbrace
+                            p.tok_i - 1, // rbrace
+                        },
+                    },
                 });
             },
             else => {

lib/std/zig/render.zig

@@ -739,8 +739,7 @@ fn renderExpression(r: *Render, node: Ast.Node.Index, space: Space) Error!void {
 
         .error_set_decl => {
             const error_token = tree.nodeMainToken(node);
-            const lbrace = error_token + 1;
-            const rbrace = tree.nodeData(node).token;
+            const lbrace, const rbrace = tree.nodeData(node).token_and_token;
 
             try renderToken(r, error_token, .none);