No field support for field names that are not Rust identifiers in #[instrument]

[jerusdp]

Bug Report

Version

tracing v0.1.26
│ │ │ │ ├── tracing-attributes v0.1.15 (proc-macro)
│ │ │ │ └── tracing-core v0.1.18

Platform

Linux odin 5.10.16.3-microsoft-standard-WSL2 #1 SMP Fri Apr 2 22:23:49 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Description

I cannot construct a field on the instrumented trace with a name that is not a Rust ident.

Documentation indicates that all features available in span! are available in #[instrument].

(I have not tested this feature in span!).

Code:

#[instrument(name = "API Gateway event handler", skip(e, _c), fields("comment" = "Event data is not recorded as it contains personal data."))]

Expected this to happen:
A field, comment, would be created containing the note and appear in my logs.

Instead this happened:
error: expected ident
--> src/handler.rs:43:70
|
43 | #[instrument(name = "API Gateway event handler", skip(e, _c), fields("comment" = "Event data is not recorded as it contains personal data...

The editor highlights "comment" as the offending term.

[jplatte]

This shouldn't be hard to fix, you don't even have to quote things. There has to be some parsing based on Ident::parse somewhere in the proc-macro code that just has to be changed to Ident::parse_any (may also be the trait impl being used indirectly, in which case there should be some _with function that can be used). Might look into this later.

edit(1): Misunderstood the issue.
edit(2): So I'm pretty sure the way to add support for quoted keys here would be to change this field from being a Punctuated<Ident, Token![.]> (i.e. dot-separated list of identifiers) to sth. like

enum FieldName {
    Regular(Punctuated<Ident, Token![.]>),
    Quoted(LitStr),
}

and adjust parsing (if input.peek(LitStr)) and uses of field.name accordingly.