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Auto merge of #12778 - Logarithmus:feature/fix-negative-const-generics, r=flodiebold

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Support negative, `char` & `bool` const generics

Before:
![Before](https://user-images.githubusercontent.com/29541480/179379832-0c3b2a74-fef6-427e-b89f-7e31d9c37b3d.png)

After:
![After](https://user-images.githubusercontent.com/29541480/179379863-b62475dd-e7bf-41f2-b437-08dfe55951af.png)

I tried to implement stuff like `Const<{NUM1 + 3 + NUM2}>` by using already existing constant evaluation mechanism for ordinary constants, but turned out to be harder than I thought, maybe because I've never ever tinkered with compilers before
This commit is contained in:
bors 2022-07-17 17:17:39 +00:00
commit db6a85d358
11 changed files with 218 additions and 86 deletions
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17
crates/hir-def/src/body.rs
View file

@ -24,7 +24,7 @@ use syntax::{ast, AstNode, AstPtr, SyntaxNodePtr};
use crate::{
attr::{Attrs, RawAttrs},
db::DefDatabase,
expr::{Expr, ExprId, Label, LabelId, Pat, PatId},
expr::{dummy_expr_id, Expr, ExprId, Label, LabelId, Pat, PatId},
item_scope::BuiltinShadowMode,
macro_id_to_def_id,
nameres::DefMap,
@ -389,6 +389,21 @@ impl Body {
}
}
impl Default for Body {
fn default() -> Self {
Self {
body_expr: dummy_expr_id(),
exprs: Default::default(),
pats: Default::default(),
or_pats: Default::default(),
labels: Default::default(),
params: Default::default(),
block_scopes: Default::default(),
_c: Default::default(),
}
}
}
impl Index<ExprId> for Body {
type Output = Expr;

4
crates/hir-def/src/expr.rs
View file

@ -26,8 +26,10 @@ use crate::{
pub use syntax::ast::{ArithOp, BinaryOp, CmpOp, LogicOp, Ordering, RangeOp, UnaryOp};
pub type ExprId = Idx<Expr>;
/// FIXME: this is a hacky function which should be removed
pub(crate) fn dummy_expr_id() -> ExprId {
ExprId::from_raw(RawIdx::from(!0))
ExprId::from_raw(RawIdx::from(u32::MAX))
}
pub type PatId = Idx<Pat>;

92
crates/hir-def/src/type_ref.rs
View file

@ -1,14 +1,21 @@
//! HIR for references to types. Paths in these are not yet resolved. They can
//! be directly created from an ast::TypeRef, without further queries.
use std::fmt::Write;
use hir_expand::{
name::{AsName, Name},
AstId, InFile,
};
use std::{convert::TryInto, fmt::Write};
use syntax::ast::{self, HasName};
use crate::{body::LowerCtx, intern::Interned, path::Path};
use crate::{
body::LowerCtx,
builtin_type::{BuiltinInt, BuiltinType, BuiltinUint},
expr::Literal,
intern::Interned,
path::Path,
};
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub enum Mutability {
@ -178,7 +185,6 @@ impl TypeRef {
// `hir_ty` level, which would allow knowing the type of:
// let v: [u8; 2 + 2] = [0u8; 4];
let len = ConstScalarOrPath::from_expr_opt(inner.expr());
TypeRef::Array(Box::new(TypeRef::from_ast_opt(ctx, inner.ty())), len)
}
ast::Type::SliceType(inner) => {
@ -403,22 +409,31 @@ impl ConstScalarOrPath {
None => Self::Scalar(ConstScalar::Unknown),
}
}
ast::Expr::Literal(lit) => {
let lkind = lit.kind();
match lkind {
ast::LiteralKind::IntNumber(num)
if num.suffix() == None || num.suffix() == Some("usize") =>
{
Self::Scalar(
num.value()
.and_then(|v| v.try_into().ok())
.map(ConstScalar::Usize)
.unwrap_or(ConstScalar::Unknown),
)
ast::Expr::PrefixExpr(prefix_expr) => match prefix_expr.op_kind() {
Some(ast::UnaryOp::Neg) => {
let unsigned = prefix_expr
.expr()
.map_or(Self::Scalar(ConstScalar::Unknown), Self::from_expr);
// Add sign
match unsigned {
Self::Scalar(ConstScalar::UInt(num)) => {
Self::Scalar(ConstScalar::Int(-(num as i128)))
}
other => other,
}
_ => Self::Scalar(ConstScalar::Unknown),
}
}
_ => prefix_expr.expr().map_or(Self::Scalar(ConstScalar::Unknown), Self::from_expr),
},
ast::Expr::Literal(literal) => Self::Scalar(match literal.kind() {
ast::LiteralKind::IntNumber(num) => {
num.value().map(ConstScalar::UInt).unwrap_or(ConstScalar::Unknown)
}
ast::LiteralKind::Char(c) => {
c.value().map(ConstScalar::Char).unwrap_or(ConstScalar::Unknown)
}
ast::LiteralKind::Bool(f) => ConstScalar::Bool(f),
_ => ConstScalar::Unknown,
}),
_ => Self::Scalar(ConstScalar::Unknown),
}
}
@ -427,9 +442,10 @@ impl ConstScalarOrPath {
/// A concrete constant value
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum ConstScalar {
// for now, we only support the trivial case of constant evaluating the length of an array
// Note that this is u64 because the target usize may be bigger than our usize
Usize(u64),
Int(i128),
UInt(u128),
Bool(bool),
Char(char),
/// Case of an unknown value that rustc might know but we don't
// FIXME: this is a hack to get around chalk not being able to represent unevaluatable
@ -439,21 +455,37 @@ pub enum ConstScalar {
Unknown,
}
impl std::fmt::Display for ConstScalar {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
impl ConstScalar {
pub fn builtin_type(&self) -> BuiltinType {
match self {
ConstScalar::Usize(us) => us.fmt(f),
ConstScalar::Unknown => f.write_char('_'),
ConstScalar::UInt(_) | ConstScalar::Unknown => BuiltinType::Uint(BuiltinUint::U128),
ConstScalar::Int(_) => BuiltinType::Int(BuiltinInt::I128),
ConstScalar::Char(_) => BuiltinType::Char,
ConstScalar::Bool(_) => BuiltinType::Bool,
}
}
}
impl ConstScalar {
/// Gets a target usize out of the ConstScalar
pub fn as_usize(&self) -> Option<u64> {
match self {
&ConstScalar::Usize(us) => Some(us),
_ => None,
impl From<Literal> for ConstScalar {
fn from(literal: Literal) -> Self {
match literal {
Literal::Char(c) => Self::Char(c),
Literal::Bool(flag) => Self::Bool(flag),
Literal::Int(num, _) => Self::Int(num),
Literal::Uint(num, _) => Self::UInt(num),
_ => Self::Unknown,
}
}
}
impl std::fmt::Display for ConstScalar {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
match self {
ConstScalar::Int(num) => num.fmt(f),
ConstScalar::UInt(num) => num.fmt(f),
ConstScalar::Bool(flag) => flag.fmt(f),
ConstScalar::Char(c) => write!(f, "'{c}'"),
ConstScalar::Unknown => f.write_char('_'),
}
}
}

29
crates/hir-ty/src/consteval.rs
View file

@ -347,17 +347,6 @@ pub fn eval_const(
}
}
pub fn eval_usize(expr: Idx<Expr>, mut ctx: ConstEvalCtx<'_>) -> Option<u64> {
if let Ok(ce) = eval_const(expr, &mut ctx) {
match ce {
ComputedExpr::Literal(Literal::Int(x, _)) => return x.try_into().ok(),
ComputedExpr::Literal(Literal::Uint(x, _)) => return x.try_into().ok(),
_ => {}
}
}
None
}
pub(crate) fn path_to_const(
db: &dyn HirDatabase,
resolver: &Resolver,
@ -406,17 +395,14 @@ pub fn unknown_const_as_generic(ty: Ty) -> GenericArg {
}
/// Interns a constant scalar with the given type
pub fn intern_scalar_const(value: ConstScalar, ty: Ty) -> Const {
pub fn intern_const_scalar(value: ConstScalar, ty: Ty) -> Const {
ConstData { ty, value: ConstValue::Concrete(chalk_ir::ConcreteConst { interned: value }) }
.intern(Interner)
}
/// Interns a possibly-unknown target usize
pub fn usize_const(value: Option<u64>) -> Const {
intern_scalar_const(
value.map(ConstScalar::Usize).unwrap_or(ConstScalar::Unknown),
TyBuilder::usize(),
)
pub fn usize_const(value: Option<u128>) -> Const {
intern_const_scalar(value.map_or(ConstScalar::Unknown, ConstScalar::UInt), TyBuilder::usize())
}
pub(crate) fn const_eval_recover(
@ -463,7 +449,7 @@ pub(crate) fn eval_to_const<'a>(
}
}
let body = ctx.body.clone();
let ctx = ConstEvalCtx {
let mut ctx = ConstEvalCtx {
db: ctx.db,
owner: ctx.owner,
exprs: &body.exprs,
@ -471,7 +457,12 @@ pub(crate) fn eval_to_const<'a>(
local_data: HashMap::default(),
infer: &ctx.result,
};
usize_const(eval_usize(expr, ctx))
let computed_expr = eval_const(expr, &mut ctx);
let const_scalar = match computed_expr {
Ok(ComputedExpr::Literal(literal)) => literal.into(),
_ => ConstScalar::Unknown,
};
intern_const_scalar(const_scalar, TyBuilder::usize())
}
#[cfg(test)]

2
crates/hir-ty/src/infer.rs
View file

@ -605,10 +605,10 @@ impl<'a> InferenceContext<'a> {
let data = c.data(Interner);
match data.value {
ConstValue::Concrete(cc) => match cc.interned {
hir_def::type_ref::ConstScalar::Usize(_) => c,
hir_def::type_ref::ConstScalar::Unknown => {
self.table.new_const_var(data.ty.clone())
}
_ => c,
},
_ => c,
}

4
crates/hir-ty/src/infer/expr.rs
View file

@ -729,7 +729,7 @@ impl<'a> InferenceContext<'a> {
let cur_elem_ty = self.infer_expr_inner(expr, &expected);
coerce.coerce(self, Some(expr), &cur_elem_ty);
}
consteval::usize_const(Some(items.len() as u64))
consteval::usize_const(Some(items.len() as u128))
}
&Array::Repeat { initializer, repeat } => {
self.infer_expr_coerce(initializer, &Expectation::has_type(elem_ty));
@ -766,7 +766,7 @@ impl<'a> InferenceContext<'a> {
Literal::ByteString(bs) => {
let byte_type = TyKind::Scalar(Scalar::Uint(UintTy::U8)).intern(Interner);
let len = consteval::usize_const(Some(bs.len() as u64));
let len = consteval::usize_const(Some(bs.len() as u128));
let array_type = TyKind::Array(byte_type, len).intern(Interner);
TyKind::Ref(Mutability::Not, static_lifetime(), array_type).intern(Interner)

15
crates/hir-ty/src/infer/pat.rs
View file

@ -11,6 +11,7 @@ use hir_def::{
use hir_expand::name::Name;
use crate::{
consteval::intern_const_scalar,
infer::{BindingMode, Expectation, InferenceContext, TypeMismatch},
lower::lower_to_chalk_mutability,
static_lifetime, ConcreteConst, ConstValue, Interner, Substitution, Ty, TyBuilder, TyExt,
@ -262,13 +263,19 @@ impl<'a> InferenceContext<'a> {
if let &Some(slice_pat_id) = slice {
let rest_pat_ty = match expected.kind(Interner) {
TyKind::Array(_, length) => {
let length = match length.data(Interner).value {
let len = match length.data(Interner).value {
ConstValue::Concrete(ConcreteConst {
interned: ConstScalar::Usize(length),
}) => length.checked_sub((prefix.len() + suffix.len()) as u64),
interned: ConstScalar::UInt(len),
}) => len.checked_sub((prefix.len() + suffix.len()) as u128),
_ => None,
};
TyKind::Array(elem_ty.clone(), crate::consteval::usize_const(length))
TyKind::Array(
elem_ty.clone(),
intern_const_scalar(
len.map_or(ConstScalar::Unknown, |len| ConstScalar::UInt(len)),
TyBuilder::usize(),
),
)
}
_ => TyKind::Slice(elem_ty.clone()),
}

7
crates/hir-ty/src/interner.rs
View file

@ -257,12 +257,7 @@ impl chalk_ir::interner::Interner for Interner {
c1: &Self::InternedConcreteConst,
c2: &Self::InternedConcreteConst,
) -> bool {
match (c1, c2) {
(&ConstScalar::Usize(a), &ConstScalar::Usize(b)) => a == b,
// we were previously assuming this to be true, I'm not whether true or false on
// unknown values is safer.
(_, _) => true,
}
(c1 == &ConstScalar::Unknown) || (c2 == &ConstScalar::Unknown) || (c1 == c2)
}
fn intern_generic_arg(

4
crates/hir-ty/src/lower.rs
View file

@ -44,7 +44,7 @@ use syntax::{ast, SmolStr};
use crate::{
all_super_traits,
consteval::{intern_scalar_const, path_to_const, unknown_const, unknown_const_as_generic},
consteval::{intern_const_scalar, path_to_const, unknown_const, unknown_const_as_generic},
db::HirDatabase,
make_binders,
mapping::ToChalk,
@ -1743,7 +1743,7 @@ pub(crate) fn const_or_path_to_chalk(
debruijn: DebruijnIndex,
) -> Const {
match value {
ConstScalarOrPath::Scalar(s) => intern_scalar_const(s.clone(), expected_ty),
ConstScalarOrPath::Scalar(s) => intern_const_scalar(s.clone(), expected_ty),
ConstScalarOrPath::Path(n) => {
let path = ModPath::from_segments(PathKind::Plain, Some(n.clone()));
path_to_const(db, resolver, &path, mode, args, debruijn)

30
crates/ide/src/hover.rs
View file

@ -173,27 +173,17 @@ pub(crate) fn hover_for_definition(
Definition::BuiltinType(_) => Some(FamousDefs(sema, sema.scope(node)?.krate())),
_ => None,
};
if let Some(markup) = render::definition(sema.db, definition, famous_defs.as_ref(), config) {
let mut res = HoverResult::default();
res.markup = render::process_markup(sema.db, definition, &markup, config);
if let Some(action) = show_implementations_action(sema.db, definition) {
res.actions.push(action);
render::definition(sema.db, definition, famous_defs.as_ref(), config).map(|markup| {
HoverResult {
markup: render::process_markup(sema.db, definition, &markup, config),
actions: show_implementations_action(sema.db, definition)
.into_iter()
.chain(show_fn_references_action(sema.db, definition))
.chain(runnable_action(sema, definition, file_id))
.chain(goto_type_action_for_def(sema.db, definition))
.collect(),
}
if let Some(action) = show_fn_references_action(sema.db, definition) {
res.actions.push(action);
}
if let Some(action) = runnable_action(sema, definition, file_id) {
res.actions.push(action);
}
if let Some(action) = goto_type_action_for_def(sema.db, definition) {
res.actions.push(action);
}
return Some(res);
}
None
})
}
fn hover_ranged(

100
crates/ide/src/hover/tests.rs
View file

@ -2958,6 +2958,106 @@ struct S$0T<const C: usize = 1, T = Foo>(T);
);
}
#[test]
fn const_generic_positive_i8_literal() {
check(
r#"
struct Const<const N: i8>;
fn main() {
let v$0alue = Const::<1>;
}
"#,
expect![[r#"
*value*
```rust
let value: Const<1>
```
"#]],
);
}
#[test]
fn const_generic_zero_i8_literal() {
check(
r#"
struct Const<const N: i8>;
fn main() {
let v$0alue = Const::<0>;
}
"#,
expect![[r#"
*value*
```rust
let value: Const<0>
```
"#]],
);
}
#[test]
fn const_generic_negative_i8_literal() {
check(
r#"
struct Const<const N: i8>;
fn main() {
let v$0alue = Const::<-1>;
}
"#,
expect![[r#"
*value*
```rust
let value: Const<-1>
```
"#]],
);
}
#[test]
fn const_generic_bool_literal() {
check(
r#"
struct Const<const F: bool>;
fn main() {
let v$0alue = Const::<true>;
}
"#,
expect![[r#"
*value*
```rust
let value: Const<true>
```
"#]],
);
}
#[test]
fn const_generic_char_literal() {
check(
r#"
struct Const<const C: char>;
fn main() {
let v$0alue = Const::<'🦀'>;
}
"#,
expect![[r#"
*value*
```rust
let value: Const<'🦀'>
```
"#]],
);
}
#[test]
fn hover_self_param_shows_type() {
check(