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Make many MacResult methods unreachable. #142061

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Make many MacResult methods unreachable. #142061

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79 changes: 16 additions & 63 deletions compiler/rustc_expand/src/base.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -390,37 +390,37 @@ macro_rules! make_stmts_default {
pub trait MacResult {
/// Creates an expression.
fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
None
unreachable!();
}

/// Creates zero or more items.
fn make_items(self: Box<Self>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
None
unreachable!();
}

/// Creates zero or more impl items.
fn make_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
None
unreachable!();
}

/// Creates zero or more impl items.
fn make_trait_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
None
unreachable!();
}

/// Creates zero or more trait items.
fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
None
unreachable!();
}

/// Creates zero or more items in an `extern {}` block
fn make_foreign_items(self: Box<Self>) -> Option<SmallVec<[P<ast::ForeignItem>; 1]>> {
None
unreachable!();
}

/// Creates a pattern.
fn make_pat(self: Box<Self>) -> Option<P<ast::Pat>> {
None
unreachable!();
}

/// Creates zero or more statements.
Expand All @@ -432,39 +432,39 @@ pub trait MacResult {
}

fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
None
unreachable!();
}

fn make_arms(self: Box<Self>) -> Option<SmallVec<[ast::Arm; 1]>> {
None
unreachable!();
}

fn make_expr_fields(self: Box<Self>) -> Option<SmallVec<[ast::ExprField; 1]>> {
None
unreachable!();
}

fn make_pat_fields(self: Box<Self>) -> Option<SmallVec<[ast::PatField; 1]>> {
None
unreachable!();
}

fn make_generic_params(self: Box<Self>) -> Option<SmallVec<[ast::GenericParam; 1]>> {
None
unreachable!();
}

fn make_params(self: Box<Self>) -> Option<SmallVec<[ast::Param; 1]>> {
None
unreachable!();
}

fn make_field_defs(self: Box<Self>) -> Option<SmallVec<[ast::FieldDef; 1]>> {
None
unreachable!();
}

fn make_variants(self: Box<Self>) -> Option<SmallVec<[ast::Variant; 1]>> {
None
unreachable!();
}

fn make_where_predicates(self: Box<Self>) -> Option<SmallVec<[ast::WherePredicate; 1]>> {
None
unreachable!();
}

fn make_crate(self: Box<Self>) -> Option<ast::Crate> {
Expand Down Expand Up @@ -501,9 +501,6 @@ make_MacEager! {
expr: P<ast::Expr>,
pat: P<ast::Pat>,
items: SmallVec<[P<ast::Item>; 1]>,
impl_items: SmallVec<[P<ast::AssocItem>; 1]>,
trait_items: SmallVec<[P<ast::AssocItem>; 1]>,
foreign_items: SmallVec<[P<ast::ForeignItem>; 1]>,
stmts: SmallVec<[ast::Stmt; 1]>,
ty: P<ast::Ty>,
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MacEager can certainly be trimmed further, only MacEager::{expr, items, ty} are actually used in built-in macros, the other fields are never set to anything other than None and their uses can be replaced with None.

}
Expand All @@ -517,22 +514,6 @@ impl MacResult for MacEager {
self.items
}

fn make_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
self.impl_items
}

fn make_trait_impl_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
self.impl_items
}

fn make_trait_items(self: Box<Self>) -> Option<SmallVec<[P<ast::AssocItem>; 1]>> {
self.trait_items
}

fn make_foreign_items(self: Box<Self>) -> Option<SmallVec<[P<ast::ForeignItem>; 1]>> {
self.foreign_items
}

fn make_stmts(self: Box<Self>) -> Option<SmallVec<[ast::Stmt; 1]>> {
match self.stmts.as_ref().map_or(0, |s| s.len()) {
0 => make_stmts_default!(self),
Expand Down Expand Up @@ -654,34 +635,6 @@ impl MacResult for DummyResult {
}))
}

fn make_arms(self: Box<DummyResult>) -> Option<SmallVec<[ast::Arm; 1]>> {
Some(SmallVec::new())
}

fn make_expr_fields(self: Box<DummyResult>) -> Option<SmallVec<[ast::ExprField; 1]>> {
Some(SmallVec::new())
}

fn make_pat_fields(self: Box<DummyResult>) -> Option<SmallVec<[ast::PatField; 1]>> {
Some(SmallVec::new())
}

fn make_generic_params(self: Box<DummyResult>) -> Option<SmallVec<[ast::GenericParam; 1]>> {
Some(SmallVec::new())
}

fn make_params(self: Box<DummyResult>) -> Option<SmallVec<[ast::Param; 1]>> {
Some(SmallVec::new())
}

fn make_field_defs(self: Box<DummyResult>) -> Option<SmallVec<[ast::FieldDef; 1]>> {
Some(SmallVec::new())
}

fn make_variants(self: Box<DummyResult>) -> Option<SmallVec<[ast::Variant; 1]>> {
Some(SmallVec::new())
}
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We need

  • a test using #[rustfmt::skip] in all possible attribute positions,
  • a test using log_syntax!() in all possible fn-like macro positions,
  • and a test using include!() or concat_idents!() in all possible fn-like macro positions.

If all of those do not crash, then we can keep the unreachable!s.


fn make_crate(self: Box<DummyResult>) -> Option<ast::Crate> {
Some(ast::Crate {
attrs: Default::default(),
Expand Down
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