Move desc out of WorkItem::short_description to allow reusing in a future commit

Author: bjorn3

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -714,48 +714,48 @@ pub(crate) enum WorkItem<B: WriteBackendMethods> {
  ThinLto(lto::ThinModule<B>),
 }
 
+// `pthread_setname()` on *nix ignores anything beyond the first 15
+// bytes. Use short descriptions to maximize the space available for
+// the module name.
+#[cfg(not(windows))]
+fn desc(short: &str, _long: &str, name: &str) -> String {
+ // The short label is three bytes, and is followed by a space. That
+ // leaves 11 bytes for the CGU name. How we obtain those 11 bytes
+ // depends on the CGU name form.
+ //
+ // - Non-incremental, e.g. `regex.f10ba03eb5ec7975-cgu.0`: the part
+ // before the `-cgu.0` is the same for every CGU, so use the
+ // `cgu.0` part. The number suffix will be different for each
+ // CGU.
+ //
+ // - Incremental (normal), e.g. `2i52vvl2hco29us0`: use the whole
+ // name because each CGU will have a unique ASCII hash, and the
+ // first 11 bytes will be enough to identify it.
+ //
+ // - Incremental (with `-Zhuman-readable-cgu-names`), e.g.
+ // `regex.f10ba03eb5ec7975-re_builder.volatile`: use the whole
+ // name. The first 11 bytes won't be enough to uniquely identify
+ // it, but no obvious substring will, and this is a rarely used
+ // option so it doesn't matter much.
+ //
+ assert_eq!(short.len(), 3);
+ let name = if let Some(index) = name.find("-cgu.") {
+ &name[index + 1..] // +1 skips the leading '-'.
+ } else {
+ name
+ };
+ format!("{short} {name}")
+}
+
+// Windows has no thread name length limit, so use more descriptive names.
+#[cfg(windows)]
+fn desc(_short: &str, long: &str, name: &str) -> String {
+ format!("{long} {name}")
+}
+
 impl<B: WriteBackendMethods> WorkItem<B> {
  /// Generate a short description of this work item suitable for use as a thread name.
  fn short_description(&self) -> String {
- // `pthread_setname()` on *nix ignores anything beyond the first 15
- // bytes. Use short descriptions to maximize the space available for
- // the module name.
- #[cfg(not(windows))]
- fn desc(short: &str, _long: &str, name: &str) -> String {
- // The short label is three bytes, and is followed by a space. That
- // leaves 11 bytes for the CGU name. How we obtain those 11 bytes
- // depends on the CGU name form.
- //
- // - Non-incremental, e.g. `regex.f10ba03eb5ec7975-cgu.0`: the part
- // before the `-cgu.0` is the same for every CGU, so use the
- // `cgu.0` part. The number suffix will be different for each
- // CGU.
- //
- // - Incremental (normal), e.g. `2i52vvl2hco29us0`: use the whole
- // name because each CGU will have a unique ASCII hash, and the
- // first 11 bytes will be enough to identify it.
- //
- // - Incremental (with `-Zhuman-readable-cgu-names`), e.g.
- // `regex.f10ba03eb5ec7975-re_builder.volatile`: use the whole
- // name. The first 11 bytes won't be enough to uniquely identify
- // it, but no obvious substring will, and this is a rarely used
- // option so it doesn't matter much.
- //
- assert_eq!(short.len(), 3);
- let name = if let Some(index) = name.find("-cgu.") {
- &name[index + 1..] // +1 skips the leading '-'.
- } else {
- name
- };
- format!("{short} {name}")
- }
-
- // Windows has no thread name length limit, so use more descriptive names.
- #[cfg(windows)]
- fn desc(_short: &str, long: &str, name: &str) -> String {
- format!("{long} {name}")
- }
-
  match self {
  WorkItem::Optimize(m) => desc("opt", "optimize module", &m.name),
  WorkItem::CopyPostLtoArtifacts(m) => desc("cpy", "copy LTO artifacts for", &m.name),