Auto merge of rust-lang#123335 - workingjubilee:rollup-4882hjs, r=workingjubilee

Rollup of 3 pull requests

Successful merges:

 - rust-lang#123320 (Fixup parsing of `rustc_never_type_options` attribute)
 - rust-lang#123323 (std::thread: set_name change for solaris/illumos.)
 - rust-lang#123327 (Update `ParamEnv` docs)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -416,13 +416,13 @@ fn parse_never_type_options_attr(
             continue;
         }
 
-        if item.has_name(sym::diverging_block_default) && fallback.is_none() {
-            let mode = item.value_str().unwrap();
-            match mode {
+        if item.has_name(sym::diverging_block_default) && block.is_none() {
+            let default = item.value_str().unwrap();
+            match default {
                 sym::unit => block = Some(DivergingBlockBehavior::Unit),
                 sym::never => block = Some(DivergingBlockBehavior::Never),
                 _ => {
-                    tcx.dcx().span_err(item.span(), format!("unknown diverging block default: `{mode}` (supported: `unit` and `never`)"));
+                    tcx.dcx().span_err(item.span(), format!("unknown diverging block default: `{default}` (supported: `unit` and `never`)"));
                 }
             };
             continue;
@@ -431,7 +431,7 @@ fn parse_never_type_options_attr(
         tcx.dcx().span_err(
             item.span(),
             format!(
-                "unknown never type option: `{}` (supported: `fallback`)",
+                "unknown or duplicate never type option: `{}` (supported: `fallback`, `diverging_block_default`)",
                 item.name_or_empty()
             ),
         );

compiler/rustc_middle/src/ty/mod.rs

@@ -1034,9 +1034,11 @@ impl PlaceholderLike for PlaceholderConst {
     }
 }
 
-/// When type checking, we use the `ParamEnv` to track
-/// details about the set of where-clauses that are in scope at this
-/// particular point.
+/// When interacting with the type system we must provide information about the
+/// environment. `ParamEnv` is the type that represents this information. See the
+/// [dev guide chapter][param_env_guide] for more information.
+///
+/// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/param_env/param_env_summary.html
 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
 pub struct ParamEnv<'tcx> {
     /// This packs both caller bounds and the reveal enum into one pointer.
@@ -1103,8 +1105,11 @@ impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ParamEnv<'tcx> {
 impl<'tcx> ParamEnv<'tcx> {
     /// Construct a trait environment suitable for contexts where
     /// there are no where-clauses in scope. Hidden types (like `impl
-    /// Trait`) are left hidden, so this is suitable for ordinary
-    /// type-checking.
+    /// Trait`) are left hidden. In majority of cases it is incorrect
+    /// to use an empty environment. See the [dev guide section][param_env_guide]
+    /// for information on what a `ParamEnv` is and how to acquire one.
+    ///
+    /// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/param_env/param_env_summary.html
     #[inline]
     pub fn empty() -> Self {
         Self::new(List::empty(), Reveal::UserFacing)

library/std/src/sys/pal/unix/thread.rs

@@ -182,8 +182,11 @@ impl Thread {
 
         if let Some(f) = pthread_setname_np.get() {
             #[cfg(target_os = "nto")]
-            let name = truncate_cstr::<{ libc::_NTO_THREAD_NAME_MAX as usize }>(name);
+            const THREAD_NAME_MAX: usize = libc::_NTO_THREAD_NAME_MAX as usize;
+            #[cfg(any(target_os = "solaris", target_os = "illumos"))]
+            const THREAD_NAME_MAX: usize = 32;
 
+            let name = truncate_cstr::<{ THREAD_NAME_MAX }>(name);
             let res = unsafe { f(libc::pthread_self(), name.as_ptr()) };
             debug_assert_eq!(res, 0);
         }