Better help text for incorrect macro_rules! usage #150899
Description
Code
macro_rules!(i_think_the_name_should_go_here) {
() => {}
}Current output
error: macros that expand to items must be delimited with braces or followed by a semicolon
--> src/lib.rs:1:13
|
1 | macro_rules!(i_think_the_name_should_go_here) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: change the delimiters to curly braces
|
1 - macro_rules!(i_think_the_name_should_go_here) {
1 + macro_rules!{i_think_the_name_should_go_here} {
|
help: add a semicolon
|
1 | macro_rules!(i_think_the_name_should_go_here); {
| +
error: expected item, found `{`
--> src/lib.rs:1:47
|
1 | macro_rules!(i_think_the_name_should_go_here) {
| ^ expected item
|
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
error: could not compile `playground` (lib) due to 2 previous errorsDesired output
help: to define a macro, remove the parentheses around the macro name
|
1 - macro_rules!(i_think_the_name_should_go_here) {
1 + macro_rules! i_think_the_name_should_go_here {
|Rationale and extra context
I was trying to define a macro from memory, and my memory failed me 😅 My brain thought the syntax was macro_rules!(macro_name) {}, but the parentheses can't go there.
I have no idea how common of a mistake this is and if it's worth special casing; I'm happy with whatever judgment call yinz make :)
Other cases
Rust Version
$ rustc --version --verbose
rustc 1.91.1 (ed61e7d7e 2025-11-07)
binary: rustc
commit-hash: ed61e7d7e242494fb7057f2657300d9e77bb4fcb
commit-date: 2025-11-07
host: aarch64-apple-darwin
release: 1.91.1
LLVM version: 21.1.2Anything else?
No response