cargo: allow dashes in lib.name

Change the cargo TOML parser to allow dashes in `lib.name`.

Cargo currently refuses explicit library names if they contain a dash.
However, if no library name is specified, the package-name will be used,
which itself can contain dashes. This leads to packages with `lib.name`
containing dashes, if their package-name contains dashes.

Drop this requirement and allow explicit `lib.name` configurations to
contain dashes.

The current ecosystem clearly allows `lib.name` to contain dashes,
given that `cargo metadata` already reports such names for any package
with a dash. It looks like an oversight that any explicit configuration
is not allowed to include dashes.

All consumers of `lib.name` already use `Target.crate_name()` rather
than `Target.name()` if a sanitized name is required. Therefore, they
already replace dashes with underscores.

Last but not least, the current documentation is simply wrong in stating
that `lib.name` defaults to the package-name with dashes replaced by
underscores. Cargo never replaces dashes for `lib.name`, and `cargo
metadata` and friends already happily show `lib.name` with dashes. Cargo
merely replaces dashes with underscores to retrieve the crate-name of a
target, which is then used as stem for library artifacts.

src/cargo/util/toml/targets.rs

@@ -152,18 +152,10 @@ fn clean_lib(
 ) -> CargoResult<Option<Target>> {
  let inferred = inferred_lib(package_root);
  let lib = match toml_lib {
- Some(lib) => {
- if let Some(ref name) = lib.name {
- // XXX: other code paths dodge this validation
- if name.contains('-') {
- anyhow::bail!("library target names cannot contain hyphens: {}", name)
- }
- }
- Some(TomlTarget {
- name: lib.name.clone().or_else(|| Some(package_name.to_owned())),
- ..lib.clone()
- })
- }
+ Some(lib) => Some(TomlTarget {
+ name: lib.name.clone().or_else(|| Some(package_name.to_owned())),
+ ..lib.clone()
+ }),
  None => inferred.as_ref().map(|lib| TomlTarget {
  name: Some(package_name.to_string()),
  path: Some(PathValue(lib.clone())),

src/doc/src/reference/cargo-targets.md

@@ -194,14 +194,15 @@ required-features = [] # Features required to build this target (N/A for lib).
 
 ### The `name` field
 
-The `name` field specifies the name of the target, which corresponds to the
-filename of the artifact that will be generated. For a library, this is the
-crate name that dependencies will use to reference it.
+The `name` field specifies the name of the target. For a binary it corresponds
+to the filename of the artifact that will be generated. For a library, with any
+dashes replaced with underscores, it corresponds to the stem used in the
+produced library artifact, as well as the name that dependencies will use to
+reference the library crate.
 
 For the `[lib]` and the default binary (`src/main.rs`), this defaults to the
-name of the package, with any dashes replaced with underscores. For other
-[auto discovered](#target-auto-discovery) targets, it defaults to the
-directory or file name.
+name of the package. For other [auto discovered](#target-auto-discovery)
+targets, it defaults to the directory or file name.
 
 This is required for all targets except `[lib]`.
 

tests/testsuite/build.rs

@@ -3496,38 +3496,6 @@ fn dashes_to_underscores() {
  assert!(p.bin("foo-bar").is_file());
 }
 
-#[cargo_test]
-fn dashes_in_crate_name_bad() {
- let p = project()
- .file(
- "Cargo.toml",
- r#"
- [package]
- name = "foo"
- version = "0.0.1"
- authors = []
-
- [lib]
- name = "foo-bar"
- "#,
- )
- .file("src/lib.rs", "")
- .file("src/main.rs", "extern crate foo_bar; fn main() {}")
- .build();
-
- p.cargo("build -v")
- .with_status(101)
- .with_stderr(
- "\
-[ERROR] failed to parse manifest at `[..]/foo/Cargo.toml`
-
-Caused by:
- library target names cannot contain hyphens: foo-bar
-",
- )
- .run();
-}
-
 #[cargo_test]
 fn rustc_env_var() {
  let p = project().file("src/lib.rs", "").build();