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Auto merge of #6582 - rail-rain:ice_6539, r=flip1995

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Fix the ICE 6539

Fixes #6539

It happened because `zero_sized_map_values` used `layout_of` with types from type aliases, which is essentially the same as the ICE 4968.

---

changelog: Fix an ICE in `zero_sized_map_values`
This commit is contained in:
bors 2021-01-17 15:38:50 +00:00
commit e0d331fbf4
2 changed files with 19 additions and 1 deletions
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4
clippy_lints/src/zero_sized_map_values.rs
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@ -6,7 +6,7 @@ use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_target::abi::LayoutOf as _;
use rustc_typeck::hir_ty_to_ty;
use crate::utils::{is_type_diagnostic_item, match_type, paths, span_lint_and_help};
use crate::utils::{is_normalizable, is_type_diagnostic_item, match_type, paths, span_lint_and_help};
declare_clippy_lint! {
/// **What it does:** Checks for maps with zero-sized value types anywhere in the code.
@ -50,6 +50,8 @@ impl LateLintPass<'_> for ZeroSizedMapValues {
if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) || match_type(cx, ty, &paths::BTREEMAP);
if let Adt(_, ref substs) = ty.kind();
let ty = substs.type_at(1);
// Do this to prevent `layout_of` crashing, being unable to fully normalize `ty`.
if is_normalizable(cx, cx.param_env, ty);
if let Ok(layout) = cx.layout_of(ty);
if layout.is_zst();
then {

16
tests/ui/crashes/ice-6539.rs Normal file
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@ -0,0 +1,16 @@
// The test for the ICE 6539: https://github.com/rust-lang/rust-clippy/issues/6539.
// The cause is that `zero_sized_map_values` used `layout_of` with types from type aliases,
// which is essentially the same as the ICE 4968.
// Note that only type aliases with associated types caused the crash this time,
// not others such as trait impls.
use std::collections::{BTreeMap, HashMap};
pub trait Trait {
type Assoc;
}
type TypeAlias<T> = HashMap<(), <T as Trait>::Assoc>;
type TypeAlias2<T> = BTreeMap<(), <T as Trait>::Assoc>;
fn main() {}