Grammar: macros #458
Grammar: macros #458
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| @@ -27,11 +66,11 @@ syntax named by _designator_. Valid designators are: | |||
| * `expr`: an [expression] | |||
| * `ty`: a [type] | |||
| * `ident`: an [identifier] or [keyword] | |||
| * `path`: a [path] | |||
| * `tt`: a token tree (a single [token] by matching `()`, `[]`, or `{}`) | |||
| * `path`: a [_TypePath_] style path | |||
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Could you name the relevant production in the grammar for all of these that have one?
src/macros-by-example.md
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| * `expr` and `stmt` may only be followed by one of `=>`, `,`, or `;`. | ||
| * `pat` may only be followed by one of `=>`, `,`, `=`, `|`, `if`, or `in`. | ||
| * `path` and `ty` may only be followed by one of `=>`, `,`, `=`, `|`, `;`, | ||
| `:`, `>`, `[`, `{`, `as`, `where`, or a macro variable of `block` |
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And >> (rust-lang/rust#54977)
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Might want to add a note that >> will not work in compilers prior to 1.31. (Didn't think about backporting it to 1.30, which we could have.)
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The reference documents as it is today, not what it was yesterday. We don't care about older releases.
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| // Macro calls within macros. | ||
| macro_rules! example { | ||
| () => { println!("Macro call in a macro!") }; |
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There should be some mention that the outer macro expands to the inner macro, which is then expanded.
src/items.md
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| > | _Macro_\ | ||
| > | _MacroDefinition_\ | ||
| > | [_MacroInvocationSemi_] [^novis]\ | ||
| > | [_MacroRulesDefinition_] [^novis]\ |
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Was this deliberately not written like this?
OuterAttribute ( Visibility ? ( Module | ... | ExternBlock ) | MacroInvocationSemi | MacroRulesDefinition )
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I was trying to avoid making it too nested. In that example, there would need to be another set of parenthesis, like: OuterAttribute* ( ( Visibility? ( Module | ... | ExternBlock ) ) | MacroInvocationSemi | MacroRulesDefinition ) which seems a little unwieldy. I pushed a variation that removes the footnote, let me know if it looks any better.
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I think I prefer this version because the macro can expand to an item with a visibility.
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Thanks! |
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