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Auto merge of #59178 - oli-obk:lazy_const, r=eddyb

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Revert the `LazyConst` PR

The introduction of `LazyConst` did not actually achieve the code simplicity improvements that were the main reason it was introduced. Especially in the presence of const generics, the differences between the "levels of evaluatedness" of a constant become less clear. As it can be seen by the changes in this PR, further simplifications were possible by folding `LazyConst` back into `ConstValue`. We have been able to keep all the advantages gained during the `LazyConst` refactoring (like `const_eval` not returning an interned value, thus making all the `match` code simpler and more performant).

fixes https://github.com/rust-lang/rust/issues/59209

r? @eddyb @varkor
This commit is contained in:
bors 2019-03-17 11:17:03 +00:00
commit 070cebd0aa
56 changed files with 369 additions and 564 deletions
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16
src/librustdoc/clean/mod.rs
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@ -16,7 +16,7 @@ use rustc::infer::region_constraints::{RegionConstraintData, Constraint};
use rustc::middle::resolve_lifetime as rl;
use rustc::middle::lang_items;
use rustc::middle::stability;
use rustc::mir::interpret::GlobalId;
use rustc::mir::interpret::{GlobalId, ConstValue};
use rustc::hir::{self, GenericArg, HirVec};
use rustc::hir::def::{self, Def, CtorKind};
use rustc::hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
@ -2551,7 +2551,7 @@ impl Clean<Type> for hir::Ty {
promoted: None
};
let length = match cx.tcx.const_eval(param_env.and(cid)) {
Ok(length) => print_const(cx, ty::LazyConst::Evaluated(length)),
Ok(length) => print_const(cx, length),
Err(_) => "_".to_string(),
};
Array(box ty.clean(cx), length)
@ -2739,14 +2739,14 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
ty::Slice(ty) => Slice(box ty.clean(cx)),
ty::Array(ty, n) => {
let mut n = *cx.tcx.lift(&n).expect("array lift failed");
if let ty::LazyConst::Unevaluated(def_id, substs) = n {
if let ConstValue::Unevaluated(def_id, substs) = n.val {
let param_env = cx.tcx.param_env(def_id);
let cid = GlobalId {
instance: ty::Instance::new(def_id, substs),
promoted: None
};
if let Ok(new_n) = cx.tcx.const_eval(param_env.and(cid)) {
n = ty::LazyConst::Evaluated(new_n);
n = new_n;
}
};
let n = print_const(cx, n);
@ -3900,16 +3900,16 @@ fn name_from_pat(p: &hir::Pat) -> String {
}
}
fn print_const(cx: &DocContext<'_>, n: ty::LazyConst<'_>) -> String {
match n {
ty::LazyConst::Unevaluated(def_id, _) => {
fn print_const(cx: &DocContext<'_>, n: ty::Const<'_>) -> String {
match n.val {
ConstValue::Unevaluated(def_id, _) => {
if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(def_id) {
print_const_expr(cx, cx.tcx.hir().body_owned_by(hir_id))
} else {
inline::print_inlined_const(cx, def_id)
}
},
ty::LazyConst::Evaluated(n) => {
_ => {
let mut s = String::new();
::rustc::mir::fmt_const_val(&mut s, n).expect("fmt_const_val failed");
// array lengths are obviously usize