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Rollup of 6 pull requests #61852

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21 changes: 9 additions & 12 deletions src/librustc_typeck/astconv.rs
Original file line number Diff line number Diff line change
@@ -2157,6 +2157,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {

/// Returns the `DefId` of the constant parameter that the provided expression is a path to.
pub fn const_param_def_id(&self, expr: &hir::Expr) -> Option<DefId> {
// Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
// currently have to be wrapped in curly brackets, so it's necessary to special-case.
let expr = match &expr.node {
ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() =>
block.expr.as_ref().unwrap(),
_ => expr,
};

match &expr.node {
ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
Res::Def(DefKind::ConstParam, did) => Some(did),
@@ -2184,18 +2192,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
ty,
};

let mut expr = &tcx.hir().body(ast_const.body).value;

// Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
// currently have to be wrapped in curly brackets, so it's necessary to special-case.
if let ExprKind::Block(block, _) = &expr.node {
if block.stmts.is_empty() {
if let Some(trailing) = &block.expr {
expr = &trailing;
}
}
}

let expr = &tcx.hir().body(ast_const.body).value;
if let Some(def_id) = self.const_param_def_id(expr) {
// Find the name and index of the const parameter by indexing the generics of the
// parent item and construct a `ParamConst`.
16 changes: 16 additions & 0 deletions src/test/ui/const-generics/issue-61336-2.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
#![feature(const_generics)]
//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash

fn f<T: Copy, const N: usize>(x: T) -> [T; N] {
[x; {N}]
}

fn g<T, const N: usize>(x: T) -> [T; N] {
[x; {N}]
//~^ ERROR the trait bound `T: std::marker::Copy` is not satisfied [E0277]
}

fn main() {
let x: [u32; 5] = f::<u32, 5>(3);
assert_eq!(x, [3u32; 5]);
}
18 changes: 18 additions & 0 deletions src/test/ui/const-generics/issue-61336-2.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
warning: the feature `const_generics` is incomplete and may cause the compiler to crash
--> $DIR/issue-61336-2.rs:1:12
|
LL | #![feature(const_generics)]
| ^^^^^^^^^^^^^^

error[E0277]: the trait bound `T: std::marker::Copy` is not satisfied
--> $DIR/issue-61336-2.rs:9:5
|
LL | [x; {N}]
| ^^^^^^^^ the trait `std::marker::Copy` is not implemented for `T`
|
= help: consider adding a `where T: std::marker::Copy` bound
= note: the `Copy` trait is required because the repeated element will be copied

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.