Inconsistent name transformation of pattern matched variables eg: if let Err(...) = ...

[gxtaillon]

Hello,

I can work around this issue, but a fix may improve UX for new users.

When attempting to pattern match a Result<>, the compiler complains about the declared variable not existing.

error[E0425]: cannot find value `e` in this scope
   --> src/bin/x.rs:y:z
    |
123 |         .body(auto!(ywrite_min!(String, "{{> pages/query }}"))))
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |               |
    |               not found in this scope
    |               in this macro invocation
    | 
   ::: /home/xyz/.cargo/registry/src/github.com-1ecc6299db9ec823/yarte_derive-0.15.4/src/lib.rs:464:1
    |
464 | pub fn ywrite_min(i: TokenStream) -> TokenStream {
    | ------------------------------------------------ in this expansion of procedural macro `ywrite_min!`

Eg:

--------------v
{{#if let Err(e) = feedback }}
    <div class="error-message">{{ format!("{}", e) }}</div>
{{/if}}
------------------------------------------------^

When looking at the output using cargo-expand (cargo install cargo-expand && cargo expand), the declaration has a suffix but the use does not :

Putting the generated suffix in the source template does fix the error.

System versions:

yarte 0.15.4
rustc 1.53.0 (53cb7b09b 2021-06-17)
binary: rustc
commit-hash: 53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b
commit-date: 2021-06-17
host: x86_64-unknown-linux-gnu
release: 1.53.0
LLVM version: 12.0.1

Best,

[zzau13]

It's because variable is used as argument of macro. Wrap macro with inline function for the same result. El dom., 4 jul. 2021 3:47, Guillaume Xavier Taillon < ***@***.***> escribió:

…

Hello, I can work around this issue, but a fix may improve UX for new users. When attempting to pattern match a Result<>, the compiler complains about the declared variable not existing. error[E0425]: cannot find value `e` in this scope --> src/bin/x.rs:y:z |123 | .body(auto!(ywrite_min!(String, "{{> pages/query }}")))) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | | | not found in this scope | in this macro invocation | ::: /home/xyz/.cargo/registry/src/github.com-1ecc6299db9ec823/yarte_derive-0.15.4/src/lib.rs:464:1 |464 | pub fn ywrite_min(i: TokenStream) -> TokenStream { | ------------------------------------------------ in this expansion of procedural macro `ywrite_min!` Eg: --------------v {{#if let Err(e) = feedback }} <div class="error-message">{{ format!("{}", e) }}</div> {{/if}}------------------------------------------------^ When looking at the output using cargo-expand (cargo install cargo-expand && cargo expand), the declaration has a suffix but the use does not : [image: image] <https://user-images.githubusercontent.com/567119/124370531-be180a00-dc46-11eb-86cd-42b05569ac89.png> Putting the generated suffix in the source template does fix the error. System versions: yarte 0.15.4 rustc 1.53.0 (53cb7b09b 2021-06-17) binary: rustc commit-hash: 53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b commit-date: 2021-06-17 host: x86_64-unknown-linux-gnu release: 1.53.0 LLVM version: 12.0.1 Best, — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#230>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAUBACM6WTWGGNJ6PLZQCR3TV64T7ANCNFSM47YVZHXQ> .

[zzau13]

@gxtaillon Did this solve the problem? Any questions? Close?

[gxtaillon]

I'm not sure where I'd put an inline function. Do you have an handlebar example of what you're describing?

[zzau13]

Like,

#[inline]
fn format<D: std::fmt::Display>(e: D) -> String {
  format!("{}", e)
}

In template

{{ format(bar) }}

Remember import format function in the current module.

[zzau13]

The body of macros is not transpiled. You can use a function with the inline attribute. There is a bug #211 related to the Span of proc_macro2. If you want transpilation in the body of the macros you can create an issue with the implementation proposal on yarte_lexer.