2015-08-18 23:59:21 +02:00
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//! See docs in build/expr/mod.rs
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2019-02-07 22:28:15 +01:00
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use crate::build::Builder;
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use crate::hair::*;
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2016-09-19 22:50:00 +02:00
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use rustc::mir::*;
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2019-01-06 18:10:53 +01:00
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use rustc::ty::CanonicalUserTypeAnnotation;
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2015-08-18 23:59:21 +02:00
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2019-06-01 13:38:36 +02:00
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impl<'a, 'tcx> Builder<'a, 'tcx> {
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2015-08-18 23:59:21 +02:00
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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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2020-01-05 16:46:44 +01:00
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crate fn as_constant<M>(&mut self, expr: M) -> Constant<'tcx>
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2018-09-06 23:34:26 +02:00
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where
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M: Mirror<'tcx, Output = Expr<'tcx>>,
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2015-08-18 23:59:21 +02:00
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{
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let expr = self.hir.mirror(expr);
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self.expr_as_constant(expr)
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}
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2015-10-05 18:31:48 +02:00
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fn expr_as_constant(&mut self, expr: Expr<'tcx>) -> Constant<'tcx> {
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2015-08-18 23:59:21 +02:00
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let this = self;
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2019-12-22 23:42:04 +01:00
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let Expr { ty, temp_lifetime: _, span, kind } = expr;
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2015-09-10 21:44:44 +02:00
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match kind {
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2019-12-22 23:42:04 +01:00
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ExprKind::Scope { region_scope: _, lint_level: _, value } => this.as_constant(value),
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2018-11-16 22:56:18 +01:00
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ExprKind::Literal { literal, user_ty } => {
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2019-01-12 15:55:23 +01:00
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let user_ty = user_ty.map(|user_ty| {
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2019-01-06 18:10:53 +01:00
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this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
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span,
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2019-01-12 15:55:23 +01:00
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user_ty,
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inferred_ty: ty,
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2019-01-06 18:10:53 +01:00
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})
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2018-11-16 22:56:18 +01:00
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});
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2019-08-12 17:15:45 +02:00
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assert_eq!(literal.ty, ty);
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2019-12-22 23:42:04 +01:00
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Constant { span, user_ty, literal }
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2019-11-19 00:04:06 +01:00
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}
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2019-12-22 23:42:04 +01:00
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ExprKind::StaticRef { literal, .. } => Constant { span, user_ty: None, literal },
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2018-09-06 23:34:26 +02:00
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_ => span_bug!(span, "expression is not a valid constant {:?}", kind),
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2015-09-10 21:44:44 +02:00
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}
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2015-08-18 23:59:21 +02:00
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}
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}
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