Some combinations of features fail to build

[Jess3Jane]

What version of regex are you using?

1.5.2, or with regex-syntax 0.6.24 with rust version rustc 1.53.0-nightly (42816d61e 2021-04-24

Describe the bug at a high level.

With default features disabled some feature combinations fail to compile.

What are the steps to reproduce the behavior?

For your Cargo.toml:

[package]
name="test"
version = "0.1.0"
edition = "2018"

[dependencies]
regex-syntax = { version = "0.6.24", default-features = false, features = ["unicode-perl"] }

This will also occur if you select the same feature set through regex:

[package]
name="test"
version = "0.1.0"
edition = "2018"

[dependencies]
regex = { version = "1.5.2", default-features = false, features = ["std", "unicode-perl"] }

What is the actual behavior?

  Compiling regex-syntax v0.6.24
error[E0433]: failed to resolve: use of undeclared crate or module `unicode_tables`
   --> /home/jess/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/regex-syntax-0.6.24/src/unicode.rs:351:13
    |
351 |         use unicode_tables::perl_space::WHITE_SPACE;
    |             ^^^^^^^^^^^^^^ use of undeclared crate or module `unicode_tables`

error[E0433]: failed to resolve: use of undeclared crate or module `unicode_tables`
   --> /home/jess/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/regex-syntax-0.6.24/src/unicode.rs:375:13
    |
375 |         use unicode_tables::perl_decimal::DECIMAL_NUMBER;
    |             ^^^^^^^^^^^^^^ use of undeclared crate or module `unicode_tables`

error[E0425]: cannot find value `WHITE_SPACE` in this scope
   --> /home/jess/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/regex-syntax-0.6.24/src/unicode.rs:352:22
    |
352 |         Ok(hir_class(WHITE_SPACE))
    |                      ^^^^^^^^^^^ not found in this scope
    |
help: consider importing this constant
    |
1   | use crate::unicode_tables::perl_space::WHITE_SPACE;
    |

error[E0425]: cannot find value `DECIMAL_NUMBER` in this scope
   --> /home/jess/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/regex-syntax-0.6.24/src/unicode.rs:376:22
    |
376 |         Ok(hir_class(DECIMAL_NUMBER))
    |                      ^^^^^^^^^^^^^^ not found in this scope
    |
help: consider importing this constant
    |
1   | use crate::unicode_tables::perl_decimal::DECIMAL_NUMBER;
    |

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0425, E0433.
For more information about an error, try `rustc --explain E0425`.
error: could not compile `regex-syntax`

What is the expected behavior?

The program should compile.

[BurntSushi]

Ug. Thanks for the report. In my migration to Rust 2018, it has become apparent to me that cargo fix doesn't actually apply to all of the code. On top of that, my understanding is that CI is specifically testing the case you've reported here, so on top of cargo fix not doing what I thought it would do, I also appear to have a false confidence in CI coverage. :-/

I'll get this fixed ASAP.

[BurntSushi]

Arrgh. Turns out, CI did catch these errors, but the test script doesn't have set -x enabled, so it doesn't actually failed the build.

[BurntSushi]

This is fixed in regex 1.5.3 on crates.io.