Auto merge of rust-lang#122955 - WaffleLapkin:no-more-fallback, r=<try>

[experiment] Turn offf never type fallback

Crater experiment

Author: bors

Cargo.lock

@@ -774,7 +774,7 @@ dependencies = [
  "tracing-subscriber",
  "unified-diff",
  "walkdir",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -875,8 +875,10 @@ dependencies = [
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "248e3bacc7dc6baa3b21e405ee045c3047101a49145e7e9eca583ab4c2ca5345"
+dependencies = [
+ "loom",
+ "rand",
+]
 
 [[package]]
 name = "crypto-common"
@@ -1533,6 +1535,19 @@ dependencies = [
  "windows-bindgen",
 ]
 
+[[package]]
+name = "generator"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cc16584ff22b460a382b7feec54b23d2908d858152e5739a120b949293bd74e"
+dependencies = [
+ "cc",
+ "libc",
+ "log",
+ "rustversion",
+ "windows 0.48.0",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -2304,6 +2319,19 @@ version = "0.4.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
 
+[[package]]
+name = "loom"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e045d70ddfbc984eacfa964ded019534e8f6cbf36f6410aee0ed5cefa5a9175"
+dependencies = [
+ "cfg-if",
+ "generator",
+ "scoped-tls",
+ "tracing",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "lzma-sys"
 version = "0.1.20"
@@ -2461,13 +2489,12 @@ checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 [[package]]
 name = "miniz_oxide"
 version = "0.7.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9d811f3e15f28568be3407c8e7fdb6514c1cda3cb30683f15b6a1a1dc4ea14a7"
 dependencies = [
  "adler",
  "compiler_builtins",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
+ "simd-adler32",
 ]
 
 [[package]]
@@ -3084,6 +3111,15 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e9e1dcb320d6839f6edb64f7a4a59d39b30480d4d1765b56873f7c858538a5fe"
 
+[[package]]
+name = "quickcheck"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "588f6378e4dd99458b60ec275b4477add41ce4fa9f64dcba6f15adccb19b50d6"
+dependencies = [
+ "rand",
+]
+
 [[package]]
 name = "quine-mc_cluskey"
 version = "0.2.4"
@@ -3211,11 +3247,12 @@ dependencies = [
 [[package]]
 name = "regex"
 version = "1.8.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0ab3ca65655bb1e41f2a8c8cd662eb4fb035e67c3f78da1d61dffe89d07300f"
 dependencies = [
  "aho-corasick",
+ "lazy_static",
  "memchr",
+ "quickcheck",
+ "rand",
  "regex-syntax 0.7.5",
 ]
 
@@ -3713,7 +3750,7 @@ dependencies = [
  "thorin-dwp",
  "tracing",
  "wasm-encoder",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -3770,7 +3807,7 @@ dependencies = [
  "tempfile",
  "thin-vec",
  "tracing",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -3832,7 +3869,7 @@ dependencies = [
  "shlex",
  "time",
  "tracing",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -3884,7 +3921,7 @@ dependencies = [
  "termize",
  "tracing",
  "unicode-width",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -4582,7 +4619,7 @@ dependencies = [
  "smallvec",
  "termize",
  "tracing",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -5100,6 +5137,12 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
+[[package]]
+name = "simd-adler32"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d66dc143e6b11c1eddc06d5c423cfc97062865baf299914ab64caa38182078fe"
+
 [[package]]
 name = "siphasher"
 version = "0.3.11"
@@ -5365,7 +5408,7 @@ dependencies = [
  "libc",
  "ntapi",
  "once_cell",
- "windows",
+ "windows 0.52.0",
 ]
 
 [[package]]
@@ -6307,6 +6350,15 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
+[[package]]
+name = "windows"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e686886bc078bc1b0b600cac0147aadb815089b6e4da64016cbd754b6342700f"
+dependencies = [
+ "windows-targets 0.48.5",
+]
+
 [[package]]
 name = "windows"
 version = "0.52.0"

Cargo.toml

@@ -1,6 +1,9 @@
 [workspace]
 resolver = "1"
 members = [
+  "miniz_oxide-0.7.2",
+  "regex-1.8.4",
+  "crossbeam-utils-0.8.19",
   "compiler/rustc",
   "library/std",
   "library/sysroot",
@@ -112,5 +115,9 @@ rustc-std-workspace-core = { path = 'library/rustc-std-workspace-core' }
 rustc-std-workspace-alloc = { path = 'library/rustc-std-workspace-alloc' }
 rustc-std-workspace-std = { path = 'library/rustc-std-workspace-std' }
 
+miniz_oxide = { path = 'miniz_oxide-0.7.2' }
+regex = { path = 'regex-1.8.4' }
+crossbeam-utils = { path = 'crossbeam-utils-0.8.19' }
+
 [patch."https://github.com/rust-lang/rust-clippy"]
 clippy_lints = { path = "src/tools/clippy/clippy_lints" }

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -174,7 +174,7 @@ pub(super) fn get_metadata_xcoff<'a>(path: &Path, data: &'a [u8]) -> Result<&'a
         return Ok(&info_data[offset..(offset + len)]);
     } else {
         return Err(format!("Unable to find symbol {AIX_METADATA_SYMBOL_NAME}"));
-    };
+    }
 }
 
 pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static>> {

compiler/rustc_const_eval/src/const_eval/dummy_machine.rs

@@ -64,13 +64,13 @@ impl<'mir, 'tcx: 'mir> interpret::Machine<'mir, 'tcx> for DummyMachine {
         is_write: bool,
     ) -> InterpResult<'tcx> {
         if is_write {
-            throw_machine_stop_str!("can't write to global");
+            throw_machine_stop_str!("can't write to global")
         }
 
         // If the static allocation is mutable, then we can't const prop it as its content
         // might be different at runtime.
         if alloc.inner().mutability.is_mut() {
-            throw_machine_stop_str!("can't access mutable globals in ConstProp");
+            throw_machine_stop_str!("can't access mutable globals in ConstProp")
         }
 
         Ok(())

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -257,9 +257,7 @@ pub fn eval_to_const_value_raw_provider<'tcx>(
     // Catch such calls and evaluate them instead of trying to load a constant's MIR.
     if let ty::InstanceDef::Intrinsic(def_id) = key.value.instance.def {
         let ty = key.value.instance.ty(tcx, key.param_env);
-        let ty::FnDef(_, args) = ty.kind() else {
-            bug!("intrinsic with type {:?}", ty);
-        };
+        let ty::FnDef(_, args) = ty.kind() else { bug!("intrinsic with type {:?}", ty) };
         return eval_nullary_intrinsic(tcx, key.param_env, def_id, args).map_err(|error| {
             let span = tcx.def_span(def_id);
 

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -476,7 +476,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                             Some(CtfeValidationMode::Const { .. }) => {
                                 // We can't recursively validate `extern static`, so we better reject them.
                                 if self.ecx.tcx.is_foreign_item(did) {
-                                    throw_validation_failure!(self.path, ConstRefToExtern);
+                                    throw_validation_failure!(self.path, ConstRefToExtern)
                                 }
                             }
                             None => {}
@@ -518,14 +518,14 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                     if ptr_expected_mutbl == Mutability::Mut
                         && alloc_actual_mutbl == Mutability::Not
                     {
-                        throw_validation_failure!(self.path, MutableRefToImmutable);
+                        throw_validation_failure!(self.path, MutableRefToImmutable)
                     }
                     // In a const, everything must be completely immutable.
                     if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. })) {
                         if ptr_expected_mutbl == Mutability::Mut
                             || alloc_actual_mutbl == Mutability::Mut
                         {
-                            throw_validation_failure!(self.path, ConstRefToMutable);
+                            throw_validation_failure!(self.path, ConstRefToMutable)
                         }
                     }
                 }
@@ -621,7 +621,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 } else {
                     // Otherwise (for standalone Miri), we have to still check it to be non-null.
                     if self.ecx.scalar_may_be_null(value)? {
-                        throw_validation_failure!(self.path, NullFnPtr);
+                        throw_validation_failure!(self.path, NullFnPtr)
                     }
                 }
                 Ok(true)
@@ -786,7 +786,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         if self.ctfe_mode.is_some_and(|c| !c.allow_immutable_unsafe_cell()) {
             if !op.layout.is_zst() && !op.layout.ty.is_freeze(*self.ecx.tcx, self.ecx.param_env) {
                 if !self.in_mutable_memory(op) {
-                    throw_validation_failure!(self.path, UnsafeCellInImmutable);
+                    throw_validation_failure!(self.path, UnsafeCellInImmutable)
                 }
             }
         }
@@ -819,7 +819,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 && def.is_unsafe_cell()
             {
                 if !self.in_mutable_memory(op) {
-                    throw_validation_failure!(self.path, UnsafeCellInImmutable);
+                    throw_validation_failure!(self.path, UnsafeCellInImmutable)
                 }
             }
         }
@@ -934,7 +934,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         match op.layout.abi {
             Abi::Uninhabited => {
                 let ty = op.layout.ty;
-                throw_validation_failure!(self.path, UninhabitedVal { ty });
+                throw_validation_failure!(self.path, UninhabitedVal { ty })
             }
             Abi::Scalar(scalar_layout) => {
                 if !scalar_layout.is_uninit_valid() {

compiler/rustc_driver_impl/src/lib.rs

@@ -642,21 +642,19 @@ fn process_rlink(sess: &Session, compiler: &interface::Compiler) {
         });
         let (codegen_results, outputs) = match CodegenResults::deserialize_rlink(sess, rlink_data) {
             Ok((codegen, outputs)) => (codegen, outputs),
-            Err(err) => {
-                match err {
-                    CodegenErrors::WrongFileType => dcx.emit_fatal(RLinkWrongFileType),
-                    CodegenErrors::EmptyVersionNumber => dcx.emit_fatal(RLinkEmptyVersionNumber),
-                    CodegenErrors::EncodingVersionMismatch { version_array, rlink_version } => sess
-                        .dcx()
-                        .emit_fatal(RLinkEncodingVersionMismatch { version_array, rlink_version }),
-                    CodegenErrors::RustcVersionMismatch { rustc_version } => {
-                        dcx.emit_fatal(RLinkRustcVersionMismatch {
-                            rustc_version,
-                            current_version: sess.cfg_version,
-                        })
-                    }
-                };
-            }
+            Err(err) => match err {
+                CodegenErrors::WrongFileType => dcx.emit_fatal(RLinkWrongFileType),
+                CodegenErrors::EmptyVersionNumber => dcx.emit_fatal(RLinkEmptyVersionNumber),
+                CodegenErrors::EncodingVersionMismatch { version_array, rlink_version } => sess
+                    .dcx()
+                    .emit_fatal(RLinkEncodingVersionMismatch { version_array, rlink_version }),
+                CodegenErrors::RustcVersionMismatch { rustc_version } => {
+                    dcx.emit_fatal(RLinkRustcVersionMismatch {
+                        rustc_version,
+                        current_version: sess.cfg_version,
+                    })
+                }
+            },
         };
         if compiler.codegen_backend.link(sess, codegen_results, &outputs).is_err() {
             FatalError.raise();

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -125,9 +125,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
                             .filter(|arg| arg.is_ty_or_const())
                             .position(|arg| arg.hir_id() == hir_id)
                     })
-                    .unwrap_or_else(|| {
-                        bug!("no arg matching AnonConst in segment");
-                    });
+                    .unwrap_or_else(|| bug!("no arg matching AnonConst in segment"));
 
                 (generics, arg_index)
             } else {
@@ -164,9 +162,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
                         .filter(|arg| arg.is_ty_or_const())
                         .position(|arg| arg.hir_id() == hir_id)
                 })
-                .unwrap_or_else(|| {
-                    bug!("no arg matching AnonConst in segment");
-                });
+                .unwrap_or_else(|| bug!("no arg matching AnonConst in segment"));
 
             (tcx.generics_of(type_dependent_def), idx)
         }

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -438,6 +438,11 @@ fn parse_never_type_options_attr(
     }
 
     let fallback = fallback.unwrap_or_else(|| {
+        if true {
+            // For a crater experiment, turn off all fallback
+            return NoFallback;
+        }
+
         if tcx.features().never_type_fallback { FallbackToNiko } else { FallbackToUnit }
     });
 

compiler/rustc_hir_typeck/src/lib.rs

@@ -344,9 +344,8 @@ pub struct EnclosingBreakables<'tcx> {
 
 impl<'tcx> EnclosingBreakables<'tcx> {
     fn find_breakable(&mut self, target_id: hir::HirId) -> &mut BreakableCtxt<'tcx> {
-        self.opt_find_breakable(target_id).unwrap_or_else(|| {
-            bug!("could not find enclosing breakable with id {}", target_id);
-        })
+        self.opt_find_breakable(target_id)
+            .unwrap_or_else(|| bug!("could not find enclosing breakable with id {}", target_id))
     }
 
     fn opt_find_breakable(&mut self, target_id: hir::HirId) -> Option<&mut BreakableCtxt<'tcx>> {

compiler/rustc_lint/src/types.rs

@@ -1118,7 +1118,7 @@ pub(crate) fn repr_nullable_ptr<'tcx>(
                 WrappingRange { start, end } => {
                     unreachable!("Unhandled start and end range: ({}, {})", start, end)
                 }
-            };
+            }
         }
     }
     None