zig fmt: seperate errors in error sets with comments

Author: gooncreeper

lib/std/zig/parser_test.zig

@@ -6107,6 +6107,37 @@ test "zig fmt: indentation of comments within catch, else, orelse" {
     );
 }
 
+test "zig fmt: seperate errors in error sets with comments" {
+    try testTransform(
+        \\error{
+        \\    /// This error is very bad!
+        \\    A, B}
+        \\
+    ,
+        \\error{
+        \\    /// This error is very bad!
+        \\    A,
+        \\    B,
+        \\}
+        \\
+    );
+
+    try testTransform(
+        \\error{
+        \\    A, B
+        \\    // something important
+        \\}
+        \\
+    ,
+        \\error{
+        \\    A,
+        \\    B,
+        \\    // something important
+        \\}
+        \\
+    );
+}
+
 test "recovery: top level" {
     try testError(
         \\test "" {inline}

lib/std/zig/render.zig

@@ -753,39 +753,52 @@ fn renderExpression(r: *Render, node: Ast.Node.Index, space: Space) Error!void {
                 try renderToken(r, lbrace, .none);
                 try renderIdentifier(r, lbrace + 1, .none, .eagerly_unquote); // identifier
                 return renderToken(r, rbrace, space);
-            } else if (tree.tokenTag(rbrace - 1) == .comma) {
-                // There is a trailing comma so render each member on a new line.
-                try ais.pushIndent(.normal);
-                try renderToken(r, lbrace, .newline);
-                var i = lbrace + 1;
-                while (i < rbrace) : (i += 1) {
-                    if (i > lbrace + 1) try renderExtraNewlineToken(r, i);
-                    switch (tree.tokenTag(i)) {
-                        .doc_comment => try renderToken(r, i, .newline),
-                        .identifier => {
-                            try ais.pushSpace(.comma);
-                            try renderIdentifier(r, i, .comma, .eagerly_unquote);
-                            ais.popSpace();
-                        },
-                        .comma => {},
-                        else => unreachable,
-                    }
-                }
-                ais.popIndent();
-                return renderToken(r, rbrace, space);
             } else {
-                // There is no trailing comma so render everything on one line.
-                try renderToken(r, lbrace, .space);
-                var i = lbrace + 1;
-                while (i < rbrace) : (i += 1) {
-                    switch (tree.tokenTag(i)) {
-                        .doc_comment => unreachable, // TODO
-                        .identifier => try renderIdentifier(r, i, .comma_space, .eagerly_unquote),
-                        .comma => {},
-                        else => unreachable,
+                // If there is a trailing comma, comment, or document comment, then render each
+                // item on its own line.
+                const multi_line = tree.tokenTag(rbrace - 1) == .comma or
+                    hasComment(tree, lbrace, rbrace) or
+                    blk: {
+                        var i = lbrace + 1;
+                        break :blk while (i < rbrace) : (i += 1) {
+                            if (tree.tokenTag(i) == .doc_comment)
+                                break true;
+                        } else false;
+                    };
+
+                if (multi_line) {
+                    // There is a trailing comma so render each member on a new line.
+                    try ais.pushIndent(.normal);
+                    try renderToken(r, lbrace, .newline);
+                    var i = lbrace + 1;
+                    while (i < rbrace) : (i += 1) {
+                        if (i > lbrace + 1) try renderExtraNewlineToken(r, i);
+                        switch (tree.tokenTag(i)) {
+                            .doc_comment => try renderToken(r, i, .newline),
+                            .identifier => {
+                                try ais.pushSpace(.comma);
+                                try renderIdentifier(r, i, .comma, .eagerly_unquote);
+                                ais.popSpace();
+                            },
+                            .comma => {},
+                            else => unreachable,
+                        }
                     }
+                    ais.popIndent();
+                    return renderToken(r, rbrace, space);
+                } else {
+                    // There is no trailing comma so render everything on one line.
+                    try renderToken(r, lbrace, .space);
+                    var i = lbrace + 1;
+                    while (i < rbrace) : (i += 1) {
+                        switch (tree.tokenTag(i)) {
+                            .identifier => try renderIdentifier(r, i, .comma_space, .eagerly_unquote),
+                            .comma => {},
+                            else => unreachable,
+                        }
+                    }
+                    return renderToken(r, rbrace, space);
                 }
-                return renderToken(r, rbrace, space);
             }
         },