Clean up cfg name checks

src/lib.rs

@@ -213,11 +213,14 @@ pub fn declare_feature(name: &str, enabled: bool) {
 ///
 /// See also: [`declare_cfg_values()`].
 pub fn declare_cfg(name: &str, enabled: bool) {
- if name.chars().any(|c| !c.is_ascii_alphanumeric()) {
+ if name.chars().any(|c| !c.is_ascii_alphanumeric() && c != '_') {
  panic!("Invalid cfg name {name}");
  }
  // Use #[cfg(version = "1.80.0")] when RFC 2523 finally lands
- if rustc_version().map(|v| !v.cmp(&(1, 80, 0)).is_lt()).unwrap_or(true) {
+ if rustc_version()
+ .map(|v| !v.cmp(&(1, 80, 0)).is_lt())
+ .unwrap_or(true)
+ {
  println!("cargo:rustc-check-cfg=cfg({name})");
  }
  if enabled {
@@ -251,11 +254,14 @@ pub fn enable_cfg(name: &str) {
 /// Call this before calling [`set_cfg_value()`] to avoid compiler warnings about unrecognized cfg
 /// values under rust 1.80+.
 pub fn declare_cfg_values(name: &str, values: &[&str]) {
- if name.chars().any(|c| !c.is_ascii_alphanumeric()) {
+ if name.chars().any(|c| !c.is_ascii_alphanumeric() && c != '_') {
  panic!("Invalid cfg name {name}");
  }
  // Use #[cfg(version = "1.80.0")] when RFC 2523 finally lands
- if rustc_version().map(|v| !v.cmp(&(1, 80, 0)).is_lt()).unwrap_or(true) {
+ if rustc_version()
+ .map(|v| !v.cmp(&(1, 80, 0)).is_lt())
+ .unwrap_or(true)
+ {
  let payload = values
  .iter()
  .inspect(|value| {
@@ -897,7 +903,7 @@ impl From<cc::Build> for Target {
 
 /// Sanitizes a string for use in a file name
 fn fs_sanitize(s: &str) -> Cow<'_, str> {
- if s.chars().all(|c| c.is_ascii_alphanumeric()) {
+ if s.chars().all(|c| c.is_ascii_alphanumeric() || c == '_') {
  return Cow::Borrowed(s);
  }