Skip to content

minor: Improve resilience of match checking #10213

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Sep 12, 2021
Merged

minor: Improve resilience of match checking #10213

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 2 additions & 18 deletions crates/hir_ty/src/diagnostics/expr.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ use crate::{
};

pub(crate) use hir_def::{
body::{Body, BodySourceMap},
body::Body,
expr::{Expr, ExprId, MatchArm, Pat, PatId},
LocalFieldId, VariantId,
};
Expand Down Expand Up @@ -264,8 +264,7 @@ impl ExprValidator {
db: &dyn HirDatabase,
infer: Arc<InferenceResult>,
) {
let (body, source_map): (Arc<Body>, Arc<BodySourceMap>) =
db.body_with_source_map(self.owner);
let body = db.body(self.owner);

let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() {
return;
Expand Down Expand Up @@ -330,21 +329,6 @@ impl ExprValidator {
infer: &infer,
db,
pattern_arena: &pattern_arena,
panic_context: &|| {
use syntax::AstNode;
let match_expr_text = source_map
.expr_syntax(match_expr)
.ok()
.and_then(|scrutinee_sptr| {
let root = scrutinee_sptr.file_syntax(db.upcast());
scrutinee_sptr.value.to_node(&root).syntax().parent()
})
.map(|node| node.to_string());
format!(
"expression:\n{}",
match_expr_text.as_deref().unwrap_or("<synthesized expr>")
)
},
};
let report = compute_match_usefulness(&cx, &m_arms);

Expand Down
44 changes: 29 additions & 15 deletions crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ use std::{

use hir_def::{EnumVariantId, HasModule, LocalFieldId, VariantId};
use smallvec::{smallvec, SmallVec};
use stdx::never;

use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind};

Expand Down Expand Up @@ -324,7 +325,10 @@ impl Constructor {
PatKind::Leaf { .. } | PatKind::Deref { .. } => Single,
&PatKind::Variant { enum_variant, .. } => Variant(enum_variant),
&PatKind::LiteralBool { value } => IntRange(IntRange::from_bool(value)),
PatKind::Or { .. } => cx.bug("Or-pattern should have been expanded earlier on."),
PatKind::Or { .. } => {
never!("Or-pattern should have been expanded earlier on.");
Wildcard
}
}
}

Expand Down Expand Up @@ -371,7 +375,7 @@ impl Constructor {
/// this checks for inclusion.
// We inline because this has a single call site in `Matrix::specialize_constructor`.
#[inline]
pub(super) fn is_covered_by(&self, pcx: PatCtxt<'_>, other: &Self) -> bool {
pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_>, other: &Self) -> bool {
// This must be kept in sync with `is_covered_by_any`.
match (self, other) {
// Wildcards cover anything
Expand All @@ -396,17 +400,18 @@ impl Constructor {
// Only a wildcard pattern can match the special extra constructor.
(NonExhaustive, _) => false,

_ => pcx.cx.bug(&format!(
"trying to compare incompatible constructors {:?} and {:?}",
self, other
)),
_ => {
never!("trying to compare incompatible constructors {:?} and {:?}", self, other);
// Continue with 'whatever is covered' supposed to result in false no-error diagnostic.
true
}
}
}

/// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is
/// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is
/// assumed to have been split from a wildcard.
fn is_covered_by_any(&self, pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool {
fn is_covered_by_any(&self, _pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool {
if used_ctors.is_empty() {
return false;
}
Expand All @@ -427,7 +432,8 @@ impl Constructor {
// This constructor is never covered by anything else
NonExhaustive => false,
Str(..) | FloatRange(..) | Opaque | Missing | Wildcard => {
pcx.cx.bug(&format!("found unexpected ctor in all_ctors: {:?}", self))
never!("found unexpected ctor in all_ctors: {:?}", self);
true
}
}
}
Expand Down Expand Up @@ -683,7 +689,8 @@ impl Fields {
}
}
ty_kind => {
cx.bug(&format!("Unexpected type for `Single` constructor: {:?}", ty_kind))
never!("Unexpected type for `Single` constructor: {:?}", ty_kind);
Fields::from_single_pattern(wildcard_from_ty(ty))
}
},
Slice(..) => {
Expand Down Expand Up @@ -745,7 +752,8 @@ impl Fields {
// can ignore this issue.
TyKind::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() },
TyKind::Slice(..) | TyKind::Array(..) => {
pcx.cx.bug(&format!("bad slice pattern {:?} {:?}", ctor, pcx.ty))
never!("bad slice pattern {:?} {:?}", ctor, pcx.ty);
PatKind::Wild
}
_ => PatKind::Wild,
},
Expand All @@ -755,11 +763,17 @@ impl Fields {
Constructor::IntRange(_) => UNHANDLED,
NonExhaustive => PatKind::Wild,
Wildcard => return Pat::wildcard_from_ty(pcx.ty.clone()),
Opaque => pcx.cx.bug("we should not try to apply an opaque constructor"),
Missing => pcx.cx.bug(
"trying to apply the `Missing` constructor;\
this should have been done in `apply_constructors`",
),
Opaque => {
never!("we should not try to apply an opaque constructor");
PatKind::Wild
}
Missing => {
never!(
"trying to apply the `Missing` constructor; \
this should have been done in `apply_constructors`",
);
PatKind::Wild
}
};

Pat { ty: pcx.ty.clone(), kind: Box::new(pat) }
Expand Down
8 changes: 1 addition & 7 deletions crates/hir_ty/src/diagnostics/match_check/usefulness.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -295,7 +295,6 @@ pub(crate) struct MatchCheckCtx<'a> {
pub(crate) db: &'a dyn HirDatabase,
/// Lowered patterns from arms plus generated by the check.
pub(crate) pattern_arena: &'a RefCell<PatternArena>,
pub(crate) panic_context: &'a dyn Fn() -> String,
}

impl<'a> MatchCheckCtx<'a> {
Expand Down Expand Up @@ -328,11 +327,6 @@ impl<'a> MatchCheckCtx<'a> {
pub(super) fn type_of(&self, pat: PatId) -> Ty {
self.pattern_arena.borrow()[pat].ty.clone()
}

#[track_caller]
pub(super) fn bug(&self, info: &str) -> ! {
panic!("bug: {}\n{}", info, (self.panic_context)());
}
}

#[derive(Copy, Clone)]
Expand Down Expand Up @@ -1131,7 +1125,7 @@ pub(crate) fn compute_match_usefulness(
arms: &[MatchArm],
) -> UsefulnessReport {
let mut matrix = Matrix::empty();
let arm_usefulness: Vec<_> = arms
let arm_usefulness = arms
.iter()
.copied()
.map(|arm| {
Expand Down