Auto merge of #92664 - ehuss:rollup-t9yrvk5, r=ehuss

Rollup of 8 pull requests

Successful merges:

 - #84640 (Implement `TryFrom<char>` for `u8`)
 - #92336 (Remove &self from PrintState::to_string)
 - #92375 (Consolidate checking for msvc when generating debuginfo)
 - #92568 (Add note about non_exhaustive to variant_count)
 - #92600 (Add some missing `#[must_use]` to some `f{32,64}` operations)
 - #92610 (Create CSS class instead of using inline style for search results)
 - #92632 (Implement stabilization of `#[feature(available_parallelism)]`)
 - #92650 (Fix typo in `StableCrateId` docs)

Failed merges:

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

Author: bors

compiler/rustc_ast_pretty/src/pprust/mod.rs

@@ -73,11 +73,11 @@ pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 }
 
 pub fn to_string(f: impl FnOnce(&mut State<'_>)) -> String {
-    State::new().to_string(f)
+    State::to_string(f)
 }
 
 pub fn crate_to_string_for_macros(krate: &ast::Crate) -> String {
-    State::new().to_string(|s| {
+    State::to_string(|s| {
         s.print_inner_attributes(&krate.attrs);
         for item in &krate.items {
             s.print_item(item);

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -211,7 +211,7 @@ pub fn literal_to_string(lit: token::Lit) -> String {
 }
 
 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
-    format!("{}{}", State::new().to_string(|s| s.print_visibility(vis)), s)
+    format!("{}{}", State::to_string(|s| s.print_visibility(vis)), s)
 }
 
 impl std::ops::Deref for State<'_> {
@@ -793,55 +793,55 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     }
 
     fn ty_to_string(&self, ty: &ast::Ty) -> String {
-        self.to_string(|s| s.print_type(ty))
+        Self::to_string(|s| s.print_type(ty))
     }
 
     fn bounds_to_string(&self, bounds: &[ast::GenericBound]) -> String {
-        self.to_string(|s| s.print_type_bounds("", bounds))
+        Self::to_string(|s| s.print_type_bounds("", bounds))
     }
 
     fn pat_to_string(&self, pat: &ast::Pat) -> String {
-        self.to_string(|s| s.print_pat(pat))
+        Self::to_string(|s| s.print_pat(pat))
     }
 
     fn expr_to_string(&self, e: &ast::Expr) -> String {
-        self.to_string(|s| s.print_expr(e))
+        Self::to_string(|s| s.print_expr(e))
     }
 
     fn tt_to_string(&self, tt: &TokenTree) -> String {
-        self.to_string(|s| s.print_tt(tt, false))
+        Self::to_string(|s| s.print_tt(tt, false))
     }
 
     fn tts_to_string(&self, tokens: &TokenStream) -> String {
-        self.to_string(|s| s.print_tts(tokens, false))
+        Self::to_string(|s| s.print_tts(tokens, false))
     }
 
     fn stmt_to_string(&self, stmt: &ast::Stmt) -> String {
-        self.to_string(|s| s.print_stmt(stmt))
+        Self::to_string(|s| s.print_stmt(stmt))
     }
 
     fn item_to_string(&self, i: &ast::Item) -> String {
-        self.to_string(|s| s.print_item(i))
+        Self::to_string(|s| s.print_item(i))
     }
 
     fn generic_params_to_string(&self, generic_params: &[ast::GenericParam]) -> String {
-        self.to_string(|s| s.print_generic_params(generic_params))
+        Self::to_string(|s| s.print_generic_params(generic_params))
     }
 
     fn path_to_string(&self, p: &ast::Path) -> String {
-        self.to_string(|s| s.print_path(p, false, 0))
+        Self::to_string(|s| s.print_path(p, false, 0))
     }
 
     fn path_segment_to_string(&self, p: &ast::PathSegment) -> String {
-        self.to_string(|s| s.print_path_segment(p, false))
+        Self::to_string(|s| s.print_path_segment(p, false))
     }
 
     fn vis_to_string(&self, v: &ast::Visibility) -> String {
-        self.to_string(|s| s.print_visibility(v))
+        Self::to_string(|s| s.print_visibility(v))
     }
 
     fn block_to_string(&self, blk: &ast::Block) -> String {
-        self.to_string(|s| {
+        Self::to_string(|s| {
             // Containing cbox, will be closed by `print_block` at `}`.
             s.cbox(INDENT_UNIT);
             // Head-ibox, will be closed by `print_block` after `{`.
@@ -851,22 +851,22 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     }
 
     fn meta_list_item_to_string(&self, li: &ast::NestedMetaItem) -> String {
-        self.to_string(|s| s.print_meta_list_item(li))
+        Self::to_string(|s| s.print_meta_list_item(li))
     }
 
     fn attr_item_to_string(&self, ai: &ast::AttrItem) -> String {
-        self.to_string(|s| s.print_attr_item(ai, ai.path.span))
+        Self::to_string(|s| s.print_attr_item(ai, ai.path.span))
     }
 
     fn attribute_to_string(&self, attr: &ast::Attribute) -> String {
-        self.to_string(|s| s.print_attribute(attr))
+        Self::to_string(|s| s.print_attribute(attr))
     }
 
     fn param_to_string(&self, arg: &ast::Param) -> String {
-        self.to_string(|s| s.print_param(arg, false))
+        Self::to_string(|s| s.print_param(arg, false))
     }
 
-    fn to_string(&self, f: impl FnOnce(&mut State<'_>)) -> String {
+    fn to_string(f: impl FnOnce(&mut State<'_>)) -> String {
         let mut printer = State::new();
         f(&mut printer);
         printer.s.eof()
@@ -1202,7 +1202,7 @@ impl<'a> State<'a> {
                 );
             }
             ast::ItemKind::Mod(unsafety, ref mod_kind) => {
-                self.head(self.to_string(|s| {
+                self.head(Self::to_string(|s| {
                     s.print_visibility(&item.vis);
                     s.print_unsafety(unsafety);
                     s.word("mod");
@@ -1228,7 +1228,7 @@ impl<'a> State<'a> {
                 }
             }
             ast::ItemKind::ForeignMod(ref nmod) => {
-                self.head(self.to_string(|s| {
+                self.head(Self::to_string(|s| {
                     s.print_unsafety(nmod.unsafety);
                     s.word("extern");
                 }));
@@ -1450,7 +1450,7 @@ impl<'a> State<'a> {
                 ast::CrateSugar::JustCrate => self.word_nbsp("crate"),
             },
             ast::VisibilityKind::Restricted { ref path, .. } => {
-                let path = self.to_string(|s| s.print_path(path, false, 0));
+                let path = Self::to_string(|s| s.print_path(path, false, 0));
                 if path == "self" || path == "super" {
                     self.word_nbsp(format!("pub({})", path))
                 } else {

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -18,6 +18,7 @@ use crate::llvm::debuginfo::{
 use crate::value::Value;
 
 use cstr::cstr;
+use rustc_codegen_ssa::debuginfo::type_names::cpp_like_debuginfo;
 use rustc_codegen_ssa::traits::*;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
@@ -933,16 +934,16 @@ fn basic_type_metadata<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'l
 
     // When targeting MSVC, emit MSVC style type names for compatibility with
     // .natvis visualizers (and perhaps other existing native debuggers?)
-    let msvc_like_names = cx.tcx.sess.target.is_like_msvc;
+    let cpp_like_debuginfo = cpp_like_debuginfo(cx.tcx);
 
     let (name, encoding) = match t.kind() {
         ty::Never => ("!", DW_ATE_unsigned),
         ty::Tuple(elements) if elements.is_empty() => ("()", DW_ATE_unsigned),
         ty::Bool => ("bool", DW_ATE_boolean),
         ty::Char => ("char", DW_ATE_unsigned_char),
-        ty::Int(int_ty) if msvc_like_names => (int_ty.msvc_basic_name(), DW_ATE_signed),
-        ty::Uint(uint_ty) if msvc_like_names => (uint_ty.msvc_basic_name(), DW_ATE_unsigned),
-        ty::Float(float_ty) if msvc_like_names => (float_ty.msvc_basic_name(), DW_ATE_float),
+        ty::Int(int_ty) if cpp_like_debuginfo => (int_ty.msvc_basic_name(), DW_ATE_signed),
+        ty::Uint(uint_ty) if cpp_like_debuginfo => (uint_ty.msvc_basic_name(), DW_ATE_unsigned),
+        ty::Float(float_ty) if cpp_like_debuginfo => (float_ty.msvc_basic_name(), DW_ATE_float),
         ty::Int(int_ty) => (int_ty.name_str(), DW_ATE_signed),
         ty::Uint(uint_ty) => (uint_ty.name_str(), DW_ATE_unsigned),
         ty::Float(float_ty) => (float_ty.name_str(), DW_ATE_float),
@@ -959,7 +960,7 @@ fn basic_type_metadata<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'l
         )
     };
 
-    if !msvc_like_names {
+    if !cpp_like_debuginfo {
         return ty_metadata;
     }
 
@@ -1525,13 +1526,6 @@ fn prepare_union_metadata<'ll, 'tcx>(
 // Enums
 //=-----------------------------------------------------------------------------
 
-/// DWARF variant support is only available starting in LLVM 8, but
-/// on MSVC we have to use the fallback mode, because LLVM doesn't
-/// lower variant parts to PDB.
-fn use_enum_fallback(cx: &CodegenCx<'_, '_>) -> bool {
-    cx.sess().target.is_like_msvc
-}
-
 // FIXME(eddyb) maybe precompute this? Right now it's computed once
 // per generator monomorphization, but it doesn't depend on substs.
 fn generator_layout_and_saved_local_names<'tcx>(
@@ -1606,7 +1600,10 @@ impl<'ll, 'tcx> EnumMemberDescriptionFactory<'ll, 'tcx> {
             _ => bug!(),
         };
 
-        let fallback = use_enum_fallback(cx);
+        // While LLVM supports generating debuginfo for variant types (enums), it doesn't support
+        // lowering that debuginfo to CodeView records for msvc targets. So if we are targeting
+        // msvc, then we need to use a different, fallback encoding of the debuginfo.
+        let fallback = cpp_like_debuginfo(cx.tcx);
         // This will always find the metadata in the type map.
         let self_metadata = type_metadata(cx, self.enum_type, self.span);
 
@@ -2159,7 +2156,10 @@ fn prepare_enum_metadata<'ll, 'tcx>(
         return FinalMetadata(discriminant_type_metadata(tag.value));
     }
 
-    if use_enum_fallback(cx) {
+    // While LLVM supports generating debuginfo for variant types (enums), it doesn't support
+    // lowering that debuginfo to CodeView records for msvc targets. So if we are targeting
+    // msvc, then we need to use a different encoding of the debuginfo.
+    if cpp_like_debuginfo(tcx) {
         let discriminant_type_metadata = match layout.variants {
             Variants::Single { .. } => None,
             Variants::Multiple { tag_encoding: TagEncoding::Niche { .. }, tag, .. }