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Handle associated types in const context #70056

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Handle associated types in const context #70056

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7d8360f
Handle associated types in `const` context
estebank Mar 16, 2020
9a821e8
review comments: avoid changing the queries
estebank Mar 17, 2020
f00ead1
review comment: fix wording
estebank Mar 17, 2020
84a5706
Rework `is_const_context` to not rely on `get_parent_item`
estebank Mar 17, 2020
f02aeae
Fix `check_for_cast`
estebank Mar 18, 2020
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15 changes: 8 additions & 7 deletions src/librustc/hir/map/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -640,13 +640,13 @@ impl<'hir> Map<'hir> {
/// Used exclusively for diagnostics, to avoid suggestion function calls.
pub fn is_const_context(&self, hir_id: HirId) -> bool {
let parent_id = self.get_parent_item(hir_id);
match self.get(parent_id) {
Node::Item(&Item { kind: ItemKind::Const(..), .. })
| Node::TraitItem(&TraitItem { kind: TraitItemKind::Const(..), .. })
| Node::ImplItem(&ImplItem { kind: ImplItemKind::Const(..), .. })
| Node::AnonConst(_)
| Node::Item(&Item { kind: ItemKind::Static(..), .. }) => true,
Node::Item(&Item { kind: ItemKind::Fn(ref sig, ..), .. }) => {
match self.find(parent_id) {
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This is weird, why could find ever return None? We should fix that if it is the case (cc @Zoxc)

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This was encountered on enum variants like enum E { A = 1f64 }, but I didn't dig too deep.

Some(Node::Item(&Item { kind: ItemKind::Const(..), .. }))
| Some(Node::TraitItem(&TraitItem { kind: TraitItemKind::Const(..), .. }))
| Some(Node::ImplItem(&ImplItem { kind: ImplItemKind::Const(..), .. }))
| Some(Node::AnonConst(_))
| Some(Node::Item(&Item { kind: ItemKind::Static(..), .. })) => true,
Some(Node::Item(&Item { kind: ItemKind::Fn(ref sig, ..), .. })) => {
sig.header.constness == Constness::Const
}
_ => false,
Expand Down Expand Up @@ -738,6 +738,7 @@ impl<'hir> Map<'hir> {
| Node::Item(_)
| Node::ForeignItem(_)
| Node::TraitItem(_)
| Node::AnonConst(_)
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| Node::ImplItem(_) => return hir_id,
_ => {}
}
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1 change: 1 addition & 0 deletions src/librustc/query/mod.rs
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Expand Up @@ -437,6 +437,7 @@ rustc_queries! {
desc { |tcx| "type-checking `{}`", tcx.def_path_str(key) }
cache_on_disk_if { key.is_local() }
}

query diagnostic_only_typeck_tables_of(key: DefId) -> &'tcx ty::TypeckTables<'tcx> {
cache_on_disk_if { key.is_local() }
load_cached(tcx, id) {
Expand Down
7 changes: 7 additions & 0 deletions src/librustc_trait_selection/traits/error_reporting/suggestions.rs
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Expand Up @@ -158,6 +158,13 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
ty::Projection(projection) => (false, Some(projection)),
_ => return,
};
if self.tcx.hir().is_const_context(body_id) {
err.note(
"associated types cannot be referenced in `const` contexts, \
like the length of an array",
);
return;
}

let suggest_restriction =
|generics: &hir::Generics<'_>, msg, err: &mut DiagnosticBuilder<'_>| {
Expand Down
6 changes: 1 addition & 5 deletions src/test/ui/associated-const/associated-const-type-parameter-arrays-2.stderr
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Expand Up @@ -7,11 +7,7 @@ LL | const Y: usize;
LL | let _array = [4; <A as Foo>::Y];
| ^^^^^^^^^^^^^ the trait `Foo` is not implemented for `A`
|
help: consider further restricting this bound with `+ Foo`
--> $DIR/associated-const-type-parameter-arrays-2.rs:15:16
|
LL | pub fn test<A: Foo, B: Foo>() {
| ^^^
= note: associated types cannot be referenced in `const` contexts, like the length of an array

error: aborting due to previous error

Expand Down
6 changes: 1 addition & 5 deletions src/test/ui/associated-const/associated-const-type-parameter-arrays.stderr
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Expand Up @@ -7,11 +7,7 @@ LL | const Y: usize;
LL | let _array: [u32; <A as Foo>::Y];
| ^^^^^^^^^^^^^ the trait `Foo` is not implemented for `A`
|
help: consider further restricting this bound with `+ Foo`
--> $DIR/associated-const-type-parameter-arrays.rs:15:16
|
LL | pub fn test<A: Foo, B: Foo>() {
| ^^^
= note: associated types cannot be referenced in `const` contexts, like the length of an array

error: aborting due to previous error

Expand Down
18 changes: 0 additions & 18 deletions src/test/ui/consts/const-integer-bool-ops.rs
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@@ -1,76 +1,58 @@
const X: usize = 42 && 39;
//~^ ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `usize`, found `bool`
const ARR: [i32; X] = [99; 34];
//~^ ERROR evaluation of constant value failed

const X1: usize = 42 || 39;
//~^ ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `usize`, found `bool`
const ARR1: [i32; X1] = [99; 47];
//~^ ERROR evaluation of constant value failed

const X2: usize = -42 || -39;
//~^ ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `usize`, found `bool`
const ARR2: [i32; X2] = [99; 18446744073709551607];
//~^ ERROR evaluation of constant value failed

const X3: usize = -42 && -39;
//~^ ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `bool`, found integer
//~| ERROR mismatched types
//~| expected `usize`, found `bool`
const ARR3: [i32; X3] = [99; 6];
//~^ ERROR evaluation of constant value failed

const Y: usize = 42.0 == 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR: [i32; Y] = [99; 1];
//~^ ERROR evaluation of constant value failed

const Y1: usize = 42.0 >= 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR1: [i32; Y1] = [99; 1];
//~^ ERROR evaluation of constant value failed

const Y2: usize = 42.0 <= 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR2: [i32; Y2] = [99; 1];
//~^ ERROR evaluation of constant value failed

const Y3: usize = 42.0 > 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR3: [i32; Y3] = [99; 0];
//~^ ERROR evaluation of constant value failed

const Y4: usize = 42.0 < 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR4: [i32; Y4] = [99; 0];
//~^ ERROR evaluation of constant value failed

const Y5: usize = 42.0 != 42.0;
//~^ ERROR mismatched types
//~| expected `usize`, found `bool`
const ARRR5: [i32; Y5] = [99; 0];
//~^ ERROR evaluation of constant value failed

Expand Down
50 changes: 25 additions & 25 deletions src/test/ui/consts/const-integer-bool-ops.stderr
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Expand Up @@ -17,151 +17,151 @@ LL | const X: usize = 42 && 39;
| ^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:8:18
--> $DIR/const-integer-bool-ops.rs:5:18
|
LL | const ARR: [i32; X] = [99; 34];
| ^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:11:19
--> $DIR/const-integer-bool-ops.rs:8:19
|
LL | const X1: usize = 42 || 39;
| ^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:11:25
--> $DIR/const-integer-bool-ops.rs:8:25
|
LL | const X1: usize = 42 || 39;
| ^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:11:19
--> $DIR/const-integer-bool-ops.rs:8:19
|
LL | const X1: usize = 42 || 39;
| ^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:18:19
--> $DIR/const-integer-bool-ops.rs:12:19
|
LL | const ARR1: [i32; X1] = [99; 47];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:21:19
--> $DIR/const-integer-bool-ops.rs:15:19
|
LL | const X2: usize = -42 || -39;
| ^^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:21:26
--> $DIR/const-integer-bool-ops.rs:15:26
|
LL | const X2: usize = -42 || -39;
| ^^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:21:19
--> $DIR/const-integer-bool-ops.rs:15:19
|
LL | const X2: usize = -42 || -39;
| ^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:28:19
--> $DIR/const-integer-bool-ops.rs:19:19
|
LL | const ARR2: [i32; X2] = [99; 18446744073709551607];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:31:19
--> $DIR/const-integer-bool-ops.rs:22:19
|
LL | const X3: usize = -42 && -39;
| ^^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:31:26
--> $DIR/const-integer-bool-ops.rs:22:26
|
LL | const X3: usize = -42 && -39;
| ^^^ expected `bool`, found integer

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:31:19
--> $DIR/const-integer-bool-ops.rs:22:19
|
LL | const X3: usize = -42 && -39;
| ^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:38:19
--> $DIR/const-integer-bool-ops.rs:26:19
|
LL | const ARR3: [i32; X3] = [99; 6];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:41:18
--> $DIR/const-integer-bool-ops.rs:29:18
|
LL | const Y: usize = 42.0 == 42.0;
| ^^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:44:19
--> $DIR/const-integer-bool-ops.rs:31:19
|
LL | const ARRR: [i32; Y] = [99; 1];
| ^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:47:19
--> $DIR/const-integer-bool-ops.rs:34:19
|
LL | const Y1: usize = 42.0 >= 42.0;
| ^^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:50:20
--> $DIR/const-integer-bool-ops.rs:36:20
|
LL | const ARRR1: [i32; Y1] = [99; 1];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:53:19
--> $DIR/const-integer-bool-ops.rs:39:19
|
LL | const Y2: usize = 42.0 <= 42.0;
| ^^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:56:20
--> $DIR/const-integer-bool-ops.rs:41:20
|
LL | const ARRR2: [i32; Y2] = [99; 1];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:59:19
--> $DIR/const-integer-bool-ops.rs:44:19
|
LL | const Y3: usize = 42.0 > 42.0;
| ^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:62:20
--> $DIR/const-integer-bool-ops.rs:46:20
|
LL | const ARRR3: [i32; Y3] = [99; 0];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:65:19
--> $DIR/const-integer-bool-ops.rs:49:19
|
LL | const Y4: usize = 42.0 < 42.0;
| ^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:68:20
--> $DIR/const-integer-bool-ops.rs:51:20
|
LL | const ARRR4: [i32; Y4] = [99; 0];
| ^^ referenced constant has errors

error[E0308]: mismatched types
--> $DIR/const-integer-bool-ops.rs:71:19
--> $DIR/const-integer-bool-ops.rs:54:19
|
LL | const Y5: usize = 42.0 != 42.0;
| ^^^^^^^^^^^^ expected `usize`, found `bool`

error[E0080]: evaluation of constant value failed
--> $DIR/const-integer-bool-ops.rs:74:20
--> $DIR/const-integer-bool-ops.rs:56:20
|
LL | const ARRR5: [i32; Y5] = [99; 0];
| ^^ referenced constant has errors
Expand Down
1 change: 0 additions & 1 deletion src/test/ui/consts/const-tup-index-span.rs
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Expand Up @@ -2,7 +2,6 @@

const TUP: (usize,) = 5usize << 64;
//~^ ERROR mismatched types
//~| expected tuple, found `usize`
const ARR: [i32; TUP.0] = [];
//~^ ERROR evaluation of constant value failed

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/consts/const-tup-index-span.stderr
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Expand Up @@ -8,7 +8,7 @@ LL | const TUP: (usize,) = 5usize << 64;
found type `usize`

error[E0080]: evaluation of constant value failed
--> $DIR/const-tup-index-span.rs:6:18
--> $DIR/const-tup-index-span.rs:5:18
|
LL | const ARR: [i32; TUP.0] = [];
| ^^^ referenced constant has errors
Expand Down
8 changes: 0 additions & 8 deletions src/test/ui/consts/enum-discr-type-err.stderr
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Expand Up @@ -11,10 +11,6 @@ LL | | }
| |_- in this macro invocation
|
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
help: you can convert an `i32` to `isize` and panic if the converted value wouldn't fit
|
LL | $( $v = $s::V.try_into().unwrap(), )*
| ^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/enum-discr-type-err.rs:18:21
Expand All @@ -29,10 +25,6 @@ LL | | }
| |_- in this macro invocation
|
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
help: you can convert an `i32` to `isize` and panic if the converted value wouldn't fit
|
LL | $( $v = $s::V.try_into().unwrap(), )*
| ^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Expand Down
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