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Add basic support for array lengths in types

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This recognizes `let a = [1u8, 2, 3]` as having type `[u8; 3]` instead
of the previous `[u8; _]`. Byte strings and `[0u8; 2]` kinds of range
array declarations are unsupported as before.

I don't know why a bunch of our rustc tests had single quotes inside
strings un-escaped by `UPDATE_EXPECT=1 cargo t`, but I don't think it's
bad? Maybe something in a nightly?
This commit is contained in:
Jade 2021-05-11 05:06:33 -07:00
parent 77f0c92fd8
commit dc63fea427
12 changed files with 155 additions and 110 deletions
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26
crates/hir_ty/src/infer/expr.rs
View file

@ -3,7 +3,7 @@
use std::iter::{repeat, repeat_with};
use std::{mem, sync::Arc};
use chalk_ir::{cast::Cast, fold::Shift, Mutability, TyVariableKind};
use chalk_ir::{cast::Cast, fold::Shift, ConstData, Mutability, TyVariableKind};
use hir_def::{
expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
path::{GenericArg, GenericArgs},
@ -15,7 +15,9 @@ use stdx::always;
use syntax::ast::RangeOp;
use crate::{
autoderef, dummy_usize_const,
autoderef,
consts::ConstScalar,
dummy_usize_const,
lower::lower_to_chalk_mutability,
mapping::from_chalk,
method_resolution, op,
@ -23,7 +25,7 @@ use crate::{
static_lifetime, to_chalk_trait_id,
traits::FnTrait,
utils::{generics, Generics},
AdtId, Binders, CallableDefId, FnPointer, FnSig, FnSubst, InEnvironment, Interner,
AdtId, Binders, CallableDefId, ConstValue, FnPointer, FnSig, FnSubst, InEnvironment, Interner,
ProjectionTyExt, Rawness, Scalar, Substitution, TraitRef, Ty, TyBuilder, TyExt, TyKind,
};
@ -717,11 +719,12 @@ impl<'a> InferenceContext<'a> {
_ => self.table.new_type_var(),
};
match array {
let len = match array {
Array::ElementList(items) => {
for expr in items.iter() {
self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone()));
}
Some(items.len())
}
Array::Repeat { initializer, repeat } => {
self.infer_expr_coerce(
@ -734,10 +737,20 @@ impl<'a> InferenceContext<'a> {
TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner),
),
);
// FIXME: support length for Repeat array expressions
None
}
}
};
TyKind::Array(elem_ty, dummy_usize_const()).intern(&Interner)
let cd = ConstData {
ty: TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner),
value: ConstValue::Concrete(chalk_ir::ConcreteConst {
interned: len
.map(|len| ConstScalar::Usize(len))
.unwrap_or(ConstScalar::Unknown),
}),
};
TyKind::Array(elem_ty, cd.intern(&Interner)).intern(&Interner)
}
Expr::Literal(lit) => match lit {
Literal::Bool(..) => TyKind::Scalar(Scalar::Bool).intern(&Interner),
@ -747,6 +760,7 @@ impl<'a> InferenceContext<'a> {
}
Literal::ByteString(..) => {
let byte_type = TyKind::Scalar(Scalar::Uint(UintTy::U8)).intern(&Interner);
let array_type =
TyKind::Array(byte_type, dummy_usize_const()).intern(&Interner);
TyKind::Ref(Mutability::Not, static_lifetime(), array_type).intern(&Interner)