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internal error when translating Ast to Hir #1047

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conradludgate opened this issue Jul 17, 2023 · 0 comments
Closed

internal error when translating Ast to Hir #1047

conradludgate opened this issue Jul 17, 2023 · 0 comments
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bug fix-incoming

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@conradludgate
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What version of regex are you using?

regex-syntax 0.7.4

Describe the bug at a high level.

There are Asts that can be created that cause internal errors to be panicked when being translated into Hir.

These Ast's are nonsense, but can be generated using the Arbitrary integration.

What are the steps to reproduce the behavior?

use regex_syntax::{ast::{Span, Position, Ast, Alternation, Concat}, hir::translate::Translator};

let span = Span::splat(Position::new(0, 0, 0));
let ast = Ast::Alternation(Alternation {
    span,
    asts: vec![Ast::Concat(Concat { span, asts: vec![] })],
});

let mut t = Translator::new();
let hir_result = t.translate("", &ast);

What is the actual behavior?

panicked at 'internal error: entered unreachable code: expected expr or concat, got alt branch marker', /Users/conrad/.cargo/registry/src/index.crates.io-6f17d22bba15001f/regex-syntax-0.7.4/src/hir/translate.rs:769:17

What is the expected behavior?

Return an error case from translate
BurntSushi added a commit that referenced this issue Oct 8, 2023
@BurntSushi
syntax: fix panics that occur with non-sensical Ast values
52140fa 
These panics I do not believe can occur from an actual pattern, since
the parser will either never produce such things or will return an
error. But still, the Ast->Hir translator shouldn't panic in such cases.

Actually, the non-sensical Ast values are actually somewhat sensible,
and they don't map to invalid regexes. These panics were likely the
result of the regex crate not supporting empty patterns or "fail"
patterns particularly well in the fast. But now that we do, we can just
let the Asts through and generate the Hir you'd expect.

Fixes #1047
BurntSushi added a commit that referenced this issue Oct 9, 2023
@BurntSushi
syntax: fix panics that occur with non-sensical Ast values
218e283 
These panics I do not believe can occur from an actual pattern, since
the parser will either never produce such things or will return an
error. But still, the Ast->Hir translator shouldn't panic in such cases.

Actually, the non-sensical Ast values are actually somewhat sensible,
and they don't map to invalid regexes. These panics were likely the
result of the regex crate not supporting empty patterns or "fail"
patterns particularly well in the fast. But now that we do, we can just
let the Asts through and generate the Hir you'd expect.

Fixes #1047
BurntSushi added a commit that referenced this issue Oct 9, 2023
@BurntSushi
syntax: fix panics that occur with non-sensical Ast values
a85c72e 
These panics I do not believe can occur from an actual pattern, since
the parser will either never produce such things or will return an
error. But still, the Ast->Hir translator shouldn't panic in such cases.

Actually, the non-sensical Ast values are actually somewhat sensible,
and they don't map to invalid regexes. These panics were likely the
result of the regex crate not supporting empty patterns or "fail"
patterns particularly well in the fast. But now that we do, we can just
let the Asts through and generate the Hir you'd expect.

Fixes #1047
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@BurntSushi @conradludgate