Allow statement-generating braced macro invocations at the end of blocks #34436
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cc @durka |
| expr: Option<P<Expr>>) -> P<ast::Block> { | ||
| self.block_all(span, stmts, expr) | ||
| fn block(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Block> { | ||
| self.block_all(span, stmts) |
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Why do these two functions both exist?
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No reason -- removed block_all.
jseyfried
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To allow these braced macro invocation, this PR removes the optional expression from `ast::Block` and instead uses a `StmtKind::Expr` at the end of the statement list.
Currently, braced macro invocations in blocks can expand into statements (and items) except when they are last in a block, in which case they can only expand into expressions.
For example,
```rust
macro_rules! make_stmt {
() => { let x = 0; }
}
fn f() {
make_stmt! {} //< This is OK...
let x = 0; //< ... unless this line is commented out.
}
```
Fixes rust-lang#34418.
bors
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Jun 26, 2016
Batch up libsyntax breaking changes Batch of the following syntax-[breaking-change] changes: - #34213: Add a variant `Macro` to `TraitItemKind` - #34368: Merge the variant `QPath` of `PatKind` into the variant `PatKind::Path` - #34385: Move `syntax::ast::TokenTree` into a new module `syntax::tokenstream` - #33943: - Remove the type parameter from `visit::Visitor` - Remove `attr::WithAttrs` -- use `attr::HasAttrs` instead. - Change `fold_tt`/`fold_tts` to take token trees by value and avoid wrapping token trees in `Rc`. - Remove the field `ctxt` of `ast::Mac_` - Remove inherent method `attrs()` of types -- use the method `attrs` of `HasAttrs` instead. - #34316: - Remove `ast::Decl`/`ast::DeclKind` and add variants `Local` and `Item` to `StmtKind`. - Move the node id for statements from the `StmtKind` variants to a field of `Stmt` (making `Stmt` a struct instead of an alias for `Spanned<StmtKind>`) - Rename `ast::ExprKind::Again` to `Continue`. - #34339: Generalize and abstract `ThinAttributes` to `ThinVec<Attribute>` - Use `.into()` in convert between `Vec<Attribute>` and `ThinVec<Attribute>` - Use autoderef instead of `.as_attr_slice()` - #34436: Remove the optional expression from `ast::Block` and instead use a `StmtKind::Expr` at the end of the statement list. - #34403: Move errors into a separate crate (unlikely to cause breakage)
bors
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Jun 27, 2016
Batch up libsyntax breaking changes Batch of the following syntax-[breaking-change] changes: - #34213: Add a variant `Macro` to `TraitItemKind` - #34368: Merge the variant `QPath` of `PatKind` into the variant `PatKind::Path` - #34385: Move `syntax::ast::TokenTree` into a new module `syntax::tokenstream` - #33943: - Remove the type parameter from `visit::Visitor` - Remove `attr::WithAttrs` -- use `attr::HasAttrs` instead. - Change `fold_tt`/`fold_tts` to take token trees by value and avoid wrapping token trees in `Rc`. - Remove the field `ctxt` of `ast::Mac_` - Remove inherent method `attrs()` of types -- use the method `attrs` of `HasAttrs` instead. - #34316: - Remove `ast::Decl`/`ast::DeclKind` and add variants `Local` and `Item` to `StmtKind`. - Move the node id for statements from the `StmtKind` variants to a field of `Stmt` (making `Stmt` a struct instead of an alias for `Spanned<StmtKind>`) - Rename `ast::ExprKind::Again` to `Continue`. - #34339: Generalize and abstract `ThinAttributes` to `ThinVec<Attribute>` - Use `.into()` in convert between `Vec<Attribute>` and `ThinVec<Attribute>` - Use autoderef instead of `.as_attr_slice()` - #34436: Remove the optional expression from `ast::Block` and instead use a `StmtKind::Expr` at the end of the statement list. - #34403: Move errors into a separate crate (unlikely to cause breakage)
joshtriplett
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Dec 25, 2016
- Avoid using attributes on statements; use them on items instead. - Change a test to use std::env::VarError instead of std::fmt::Error, because the latter didn't impl Error until Rust 1.11. - Add an empty block after invocations of `error_chain!` inside functions, to work around rust-lang/rust#34436 (fixed in Rust 1.11). - Replace a single instance of `?` with `try!`. This still fails to work with 1.10 due to rust-lang/rust#22250 . Because of that issue, an invocation of `#[derive(Debug)]` inside a macro doesn't take cfg(...) attributes into account, and fails to compile due to referencing enum variants that don't exist. Posted for reference only.
joshtriplett
added a commit
to joshtriplett/error-chain
that referenced
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Dec 25, 2016
- Avoid using attributes on statements; use them on items instead. - Change a test to use std::env::VarError instead of std::fmt::Error, because the latter didn't impl Error until Rust 1.11. - Add an empty block after invocations of `error_chain!` inside functions, to work around rust-lang/rust#34436 (fixed in Rust 1.11). - Replace a single instance of `?` with `try!`. This still fails to work with 1.10 due to rust-lang/rust#22250 . Because of that issue, an invocation of `#[derive(Debug)]` inside a macro doesn't take cfg(...) attributes into account, and fails to compile due to referencing enum variants that don't exist. Posted for reference only.
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syntax-[breaking-change] cc #31645
To allow these braced macro invocation, this PR removes the optional expression from
ast::Blockand instead uses aStmtKind::Exprat the end of the statement list.Currently, braced macro invocations in blocks can expand into statements (and items) except when they are last in a block, in which case they can only expand into expressions.
For example,
Fixes #34418.
r? @nrc