Breaking change to target names containing dashes with Rust 1.79

[jschwe]

cargo-metadata output for target names changes with Rust 1.79 due to PR https://github.com/rust-lang/cargo/pull/12783 fixing issue https://github.com/rust-lang/cargo/issues/12780. (TLDR: dashes in target names are replaced with underscores starting with Rust 1.79)

Users would notice this by receiving errors that CMake can't find Rust targets with dashes in the name anymore, e.g.:

CMake Error at /Users/jschwender/Dev/corrosion/cmake/Corrosion.cmake:1172 (set_property):
  set_property could not find TARGET rustflag-test-lib.  Perhaps it has not
  yet been created.
Call Stack (most recent call first):
  CMakeLists.txt:11 (corrosion_add_target_rustflags)

Example of an affected Cargo.toml file:

[package]
name = "flags-lib"
version = "0.1.0"
edition = "2018"

[lib]
# Note how there is no explicit `name` field here.
crate-type=["staticlib"]

With Rust 1.79, corrosion would now import a crate named flags_lib, i.e. the CMake target name changed.

Affected crates

• Cargo packages which use dashes in their package name AND
• do not specify an explicit name in the [lib] section
• bin crates are NOT affected.

Solution / Required actions

• Corrosion v0.5 and later replace all dashes in imported target names with underscores, to get consistent CMake target names independent of the used Rust version. All users should upgrade from v0.4.x to v0.5.
• You will need to change the target name of rust libraries in your CMake code to use underscores.
• If you are not able to update corrosion, users can assign an explicit name in the [lib] or [[bin]] sections of their Cargo.toml manifests, and use that name in their CMake code. (Note: Cargo already forbids dashes in lib and bin target names). You may refer to https://github.com/slint-ui/slint/commit/eeb7bad4aeec0fcdef16d59f74467cf908c6af13 for an example fix, without updating corrosion.

[tronical]

We ran into the same issue but worked around it by explicitly setting lib.name (https://github.com/slint-ui/slint/commit/eeb7bad4aeec0fcdef16d59f74467cf908c6af13 ).

But I guess it also ok to do a _ -> - transformation unconditionally in corrosion.

[jschwe]

We ran into the same issue but worked around it by explicitly setting lib.name (https://github.com/slint-ui/slint/commit/eeb7bad4aeec0fcdef16d59f74467cf908c6af13 ).

Thanks - I updated the issue description, and included your commit as an example that other users could follow. If you have any suggestions to improve the issue description, feel free to edit the description.

But I guess it also ok to do a _ -> - transformation unconditionally in corrosion.

There are also crates which use _ in their package name, so such a transformation would break those users instead. I would just unconditionally transform - to _, so that corrosion matches cargos post 1.79 behavior.

[jschwe]

Corrosion v0.5 and newer unconditionally replace dashes with underscores in library names, to match the behavior of Rust 1.79 and newer.