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Inline const_param_def_id at its only use site

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This commit is contained in:
Oliver Scherer 2020-03-14 20:12:54 +01:00
parent fa5a15c7d5
commit 3f89c38bc0
1 changed files with 29 additions and 33 deletions
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62
src/librustc/ty/sty.rs
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@ -2401,26 +2401,6 @@ pub struct Const<'tcx> {
#[cfg(target_arch = "x86_64")]
static_assert_size!(Const<'_>, 48);
/// Returns the `DefId` of the constant parameter that the provided expression is a path to.
fn const_param_def_id(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.kind {
hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
block.expr.as_ref().unwrap()
}
_ => expr,
};
match &expr.kind {
hir::ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
hir::def::Res::Def(hir::def::DefKind::ConstParam, did) => Some(did),
_ => None,
},
_ => None,
}
}
impl<'tcx> Const<'tcx> {
/// Literals and const generic parameters are eagerly converted to a constant, everything else
/// becomes `Unevaluated`.
@ -2456,20 +2436,36 @@ impl<'tcx> Const<'tcx> {
}
}
let kind = if let Some(def_id) = 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`.
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let item_id = tcx.hir().get_parent_node(hir_id);
let item_def_id = tcx.hir().local_def_id(item_id);
let generics = tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id)];
let name = tcx.hir().name(hir_id);
ty::ConstKind::Param(ty::ParamConst::new(index, name))
} else {
ty::ConstKind::Unevaluated(def_id, InternalSubsts::identity_for_item(tcx, def_id), None)
// 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.kind {
hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
block.expr.as_ref().unwrap()
}
_ => expr,
};
tcx.mk_const(ty::Const { val: kind, ty })
use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
let val = match expr.kind {
ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
// Find the name and index of the const parameter by indexing the generics of
// the parent item and construct a `ParamConst`.
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
let item_id = tcx.hir().get_parent_node(hir_id);
let item_def_id = tcx.hir().local_def_id(item_id);
let generics = tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id)];
let name = tcx.hir().name(hir_id);
ty::ConstKind::Param(ty::ParamConst::new(index, name))
}
_ => ty::ConstKind::Unevaluated(
def_id,
InternalSubsts::identity_for_item(tcx, def_id),
None,
),
};
tcx.mk_const(ty::Const { val, ty })
}
#[inline]