Auto merge of #155933 - JonathanBrouwer:rollup-UBe7V6A, r=JonathanBrouwer

Rollup of 12 pull requests

Successful merges:

 - #151994 (switch to v0 mangling by default on stable)
 - #154325 (Tweak irrefutable let else warning output)
 - #155899 (`dlltool`: Set the working directory to workaround `--temp-prefix` bug)
 - #155273 (Lock stable_crate_ids once in create_crate_num)
 - #155361 (Document that CFI diverges from Rust wrt. ABI-compatibility rules)
 - #155692 (disable naked-dead-code-elimination test if no RET mnemonic is available)
 - #155747 (Update documentation for `wasm32-wali-linux-musl` after integrating n…)
 - #155768 (compiletest: Overhaul the code for running an incremental test revision)
 - #155907 (Handle hkl const closures)
 - #155910 (misc stuff from reading borrowck again :))
 - #155913 (Delete the 12 year old fixme)
 - #155920 (remove review queue triagebot mentions)

Author: bors

compiler/rustc_borrowck/src/handle_placeholders.rs

@@ -35,18 +35,18 @@ pub(crate) struct LoweredConstraints<'tcx> {
     pub(crate) placeholder_indices: PlaceholderIndices<'tcx>,
 }
 
-impl<'d, 'tcx, A: scc::Annotation> SccAnnotations<'d, 'tcx, A> {
-    pub(crate) fn init(definitions: &'d IndexVec<RegionVid, RegionDefinition<'tcx>>) -> Self {
-        Self { scc_to_annotation: IndexVec::new(), definitions }
-    }
-}
-
 /// A Visitor for SCC annotation construction.
 pub(crate) struct SccAnnotations<'d, 'tcx, A: scc::Annotation> {
     pub(crate) scc_to_annotation: IndexVec<ConstraintSccIndex, A>,
     definitions: &'d IndexVec<RegionVid, RegionDefinition<'tcx>>,
 }
 
+impl<'d, 'tcx, A: scc::Annotation> SccAnnotations<'d, 'tcx, A> {
+    pub(crate) fn init(definitions: &'d IndexVec<RegionVid, RegionDefinition<'tcx>>) -> Self {
+        Self { scc_to_annotation: IndexVec::new(), definitions }
+    }
+}
+
 impl scc::Annotations<RegionVid> for SccAnnotations<'_, '_, RegionTracker> {
     fn new(&self, element: RegionVid) -> RegionTracker {
         RegionTracker::new(element, &self.definitions[element])
@@ -118,7 +118,7 @@ impl RegionTracker {
     }
 
     /// The largest universe this SCC can name. It's the smallest
-    /// largest nameable universe of any reachable region, or
+    /// max-nameable-universe of any reachable region, or
     /// `max_nameable(r) = min (max_nameable(r') for r' reachable from r)`
     pub(crate) fn max_nameable_universe(self) -> UniverseIndex {
         self.max_nameable_universe.0
@@ -208,7 +208,7 @@ pub(super) fn region_definitions<'tcx>(
 /// graph such that there is a series of constraints
 ///    A: B: C: ... : X  where
 /// A contains a placeholder whose universe cannot be named by X,
-/// add a constraint that A: 'static. This is a safe upper bound
+/// add a constraint that X: 'static. This is a safe upper bound
 /// in the face of borrow checker/trait solver limitations that will
 /// eventually go away.
 ///
@@ -327,8 +327,6 @@ pub(crate) fn rewrite_placeholder_outlives<'tcx>(
 
     for scc in sccs.all_sccs() {
         // No point in adding 'static: 'static!
-        // This micro-optimisation makes somewhat sense
-        // because static outlives *everything*.
         if scc == sccs.scc(fr_static) {
             continue;
         }

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -501,43 +501,48 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         let mut errors_buffer = RegionErrors::new(infcx.tcx);
 
-        // If this is a closure, we can propagate unsatisfied
-        // `outlives_requirements` to our creator, so create a vector
-        // to store those. Otherwise, we'll pass in `None` to the
-        // functions below, which will trigger them to report errors
-        // eagerly.
-        let mut outlives_requirements = infcx.tcx.is_typeck_child(mir_def_id).then(Vec::new);
+        // If this is a nested body, we propagate unsatisfied
+        // outlives constraints to the parent body instead of
+        // eagerly erroing.
+        let mut propagated_outlives_requirements =
+            infcx.tcx.is_typeck_child(mir_def_id).then(Vec::new);
 
-        self.check_type_tests(infcx, outlives_requirements.as_mut(), &mut errors_buffer);
+        self.check_type_tests(infcx, propagated_outlives_requirements.as_mut(), &mut errors_buffer);
 
         debug!(?errors_buffer);
-        debug!(?outlives_requirements);
+        debug!(?propagated_outlives_requirements);
 
         // In Polonius mode, the errors about missing universal region relations are in the output
         // and need to be emitted or propagated. Otherwise, we need to check whether the
         // constraints were too strong, and if so, emit or propagate those errors.
         if infcx.tcx.sess.opts.unstable_opts.polonius.is_legacy_enabled() {
             self.check_polonius_subset_errors(
-                outlives_requirements.as_mut(),
+                propagated_outlives_requirements.as_mut(),
                 &mut errors_buffer,
                 polonius_output
                     .as_ref()
                     .expect("Polonius output is unavailable despite `-Z polonius`"),
             );
         } else {
-            self.check_universal_regions(outlives_requirements.as_mut(), &mut errors_buffer);
+            self.check_universal_regions(
+                propagated_outlives_requirements.as_mut(),
+                &mut errors_buffer,
+            );
         }
 
         debug!(?errors_buffer);
 
-        let outlives_requirements = outlives_requirements.unwrap_or_default();
+        let propagated_outlives_requirements = propagated_outlives_requirements.unwrap_or_default();
 
-        if outlives_requirements.is_empty() {
+        if propagated_outlives_requirements.is_empty() {
             (None, errors_buffer)
         } else {
             let num_external_vids = self.universal_regions().num_global_and_external_regions();
             (
-                Some(ClosureRegionRequirements { num_external_vids, outlives_requirements }),
+                Some(ClosureRegionRequirements {
+                    num_external_vids,
+                    outlives_requirements: propagated_outlives_requirements,
+                }),
                 errors_buffer,
             )
         }

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2350,6 +2350,7 @@ unsafe extern "C" {
     pub(crate) fn LLVMRustWriteValueToString(value_ref: &Value, s: &RustString);
 
     pub(crate) fn LLVMRustHasFeature(T: &TargetMachine, s: *const c_char) -> bool;
+    pub(crate) fn LLVMRustTargetHasMnemonic(T: &TargetMachine, s: *const c_char) -> bool;
 
     pub(crate) fn LLVMRustPrintTargetCPUs(TM: &TargetMachine, OutStr: &RustString);
     pub(crate) fn LLVMRustGetTargetFeaturesCount(T: &TargetMachine) -> size_t;

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -480,6 +480,10 @@ pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
     match req.kind {
         PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
         PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
+        PrintKind::BackendHasMnemonic => {
+            let mnemonic = req.arg.as_deref().expect("BackendHasMnemonic requires arg");
+            print_target_has_mnemonic(tm.raw(), mnemonic, out)
+        }
         _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
     }
 }
@@ -738,3 +742,10 @@ pub(crate) fn tune_cpu(sess: &Session) -> Option<&str> {
     let name = sess.opts.unstable_opts.tune_cpu.as_ref()?;
     Some(handle_native(name))
 }
+
+fn print_target_has_mnemonic(tm: &llvm::TargetMachine, mnemonic: &str, out: &mut String) {
+    use std::fmt::Write;
+    let cstr = SmallCStr::new(mnemonic);
+    let has_mnemonic = unsafe { llvm::LLVMRustTargetHasMnemonic(tm, cstr.as_ptr()) };
+    writeln!(out, "{}", has_mnemonic).unwrap();
+}

compiler/rustc_codegen_ssa/src/back/archive.rs

@@ -217,12 +217,10 @@ fn create_mingw_dll_import_lib(
     // able to control the *exact* spelling of each of the symbols that are being imported:
     // hence we don't want `dlltool` adding leading underscores automatically.
     let dlltool = find_binutils_dlltool(sess);
-    let temp_prefix = {
-        let mut path = PathBuf::from(&output_path);
-        path.pop();
-        path.push(lib_name);
-        path
-    };
+    // temp_prefix doesn't handle paths with spaces so
+    // use a relative path and set the current working directory
+    let cwd = output_path.parent().unwrap_or(output_path);
+    let temp_prefix = lib_name;
     // dlltool target architecture args from:
     // https://github.com/llvm/llvm-project-release-prs/blob/llvmorg-15.0.6/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp#L69
     let (dlltool_target_arch, dlltool_target_bitness) = match &sess.target.arch {
@@ -246,7 +244,8 @@ fn create_mingw_dll_import_lib(
         .arg(dlltool_target_bitness)
         .arg("--no-leading-underscore")
         .arg("--temp-prefix")
-        .arg(temp_prefix);
+        .arg(temp_prefix)
+        .current_dir(cwd);
 
     match dlltool_cmd.output() {
         Err(e) => {

compiler/rustc_data_structures/src/graph/scc/mod.rs

@@ -27,7 +27,7 @@ mod tests;
 /// the max/min element of the SCC, or all of the above.
 ///
 /// Concretely, the both merge operations must commute, e.g. where `merge`
-/// is `update_scc` and `update_reached`: `a.merge(b) == b.merge(a)`
+/// is `update_scc` and `update_reachable`: `a.merge(b) == b.merge(a)`
 ///
 /// In general, what you want is probably always min/max according
 /// to some ordering, potentially with side constraints (min x such

compiler/rustc_driver_impl/src/lib.rs

@@ -804,6 +804,9 @@ fn print_crate_info(
                 let calling_conventions = rustc_abi::all_names();
                 println_info!("{}", calling_conventions.join("\n"));
             }
+            BackendHasMnemonic => {
+                codegen_backend.print(req, &mut crate_info, sess);
+            }
             BackendHasZstd => {
                 let has_zstd: bool = codegen_backend.has_zstd();
                 println_info!("{has_zstd}");

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -19,6 +19,7 @@
 #include "llvm/IR/Verifier.h"
 #include "llvm/IRPrinter/IRPrintingPasses.h"
 #include "llvm/LTO/LTO.h"
+#include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Object/ObjectFile.h"
@@ -94,6 +95,25 @@ extern "C" bool LLVMRustHasFeature(LLVMTargetMachineRef TM,
   return MCInfo->checkFeatures(std::string("+") + Feature);
 }
 
+/// Check whether the target has a specific assembly mnemonic like `ret` or
+/// `nop`.
+/// This should be fast enough but if its not we have to look into another
+/// method of checking.
+extern "C" bool LLVMRustTargetHasMnemonic(LLVMTargetMachineRef TM,
+                                          const char *Mnemonic) {
+  TargetMachine *Target = unwrap(TM);
+  const MCInstrInfo *MII = Target->getMCInstrInfo();
+  StringRef MnemonicRef(Mnemonic);
+
+  for (unsigned i = 0; i < MII->getNumOpcodes(); i++) {
+    StringRef Name = MII->getName(i);
+    if (Name.equals_insensitive(MnemonicRef)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 enum class LLVMRustCodeModel {
   Tiny,
   Small,

compiler/rustc_middle/src/ty/context.rs

@@ -1416,12 +1416,12 @@ impl<'tcx> TyCtxt<'tcx> {
         self,
         stable_crate_id: StableCrateId,
     ) -> Result<TyCtxtFeed<'tcx, CrateNum>, CrateNum> {
-        if let Some(&existing) = self.untracked().stable_crate_ids.read().get(&stable_crate_id) {
+        let mut lock = self.untracked().stable_crate_ids.write();
+        if let Some(&existing) = lock.get(&stable_crate_id) {
             return Err(existing);
         }
-
-        let num = CrateNum::new(self.untracked().stable_crate_ids.read().len());
-        self.untracked().stable_crate_ids.write().insert(stable_crate_id, num);
+        let num = CrateNum::new(lock.len());
+        lock.insert(stable_crate_id, num);
         Ok(TyCtxtFeed { key: num, tcx: self })
     }
 

compiler/rustc_mir_build/src/errors.rs

@@ -924,22 +924,24 @@ pub(crate) struct IrrefutableLetPatternsIfLetGuard {
 }
 
 #[derive(Diagnostic)]
-#[diag(
-    "irrefutable `let...else` {$count ->
-    [one] pattern
-    *[other] patterns
-}"
-)]
-#[note(
-    "{$count ->
-    [one] this pattern always matches, so the else clause is unreachable
-    *[other] these patterns always match, so the else clause is unreachable
-}"
-)]
+#[diag("unreachable `else` clause")]
+#[note("this pattern always matches, so the else clause is unreachable")]
 pub(crate) struct IrrefutableLetPatternsLetElse {
-    pub(crate) count: usize,
-    #[help("remove this `else` block")]
-    pub(crate) else_span: Option<Span>,
+    #[subdiagnostic]
+    pub(crate) be_replaced: Option<LetElseReplacementSuggestion>,
+}
+
+#[derive(Subdiagnostic, Debug)]
+#[suggestion(
+    "consider using `let {$lhs} = {$rhs}` to match on a specific variant",
+    code = "let {lhs} = {rhs}",
+    applicability = "machine-applicable"
+)]
+pub(crate) struct LetElseReplacementSuggestion {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) lhs: String,
+    pub(crate) rhs: String,
 }
 
 #[derive(Diagnostic)]