37 lines
1.4 KiB
Rust
37 lines
1.4 KiB
Rust
//! See docs in build/expr/mod.rs
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use crate::build::Builder;
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use crate::thir::*;
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use rustc_middle::mir::*;
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use rustc_middle::ty::CanonicalUserTypeAnnotation;
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impl<'a, 'tcx> Builder<'a, 'tcx> {
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/// Compile `expr`, yielding a compile-time constant. Assumes that
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/// `expr` is a valid compile-time constant!
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crate fn as_constant(&mut self, expr: &Expr<'_, 'tcx>) -> Constant<'tcx> {
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let this = self;
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let Expr { ty, temp_lifetime: _, span, ref kind } = *expr;
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match *kind {
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ExprKind::Scope { region_scope: _, lint_level: _, value } => this.as_constant(value),
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ExprKind::Literal { literal, user_ty, const_id: _ } => {
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let user_ty = user_ty.map(|user_ty| {
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this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
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span,
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user_ty,
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inferred_ty: ty,
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})
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});
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assert_eq!(literal.ty, ty);
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Constant { span, user_ty, literal: literal.into() }
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}
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ExprKind::StaticRef { literal, .. } => {
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Constant { span, user_ty: None, literal: literal.into() }
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}
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ExprKind::ConstBlock { value } => {
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Constant { span: span, user_ty: None, literal: value.into() }
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}
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_ => span_bug!(span, "expression is not a valid constant {:?}", kind),
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}
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}
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}
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