Auto merge of rust-lang#113782 - matthiaskrgr:rollup-mmrjvx3, r=matth…

…iaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#112741 (fix typo in `rustdoc/src/what-is-rustdoc.md`)
 - rust-lang#113535 (Add a sparc-unknown-none-elf target.)
 - rust-lang#113651 (self type param infer, avoid ICE)
 - rust-lang#113770 (Generate safe stable code for derives on empty enums)

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

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -1134,20 +1134,30 @@ impl<'a> MethodDef<'a> {
         trait_: &TraitDef<'b>,
         enum_def: &'b EnumDef,
         type_ident: Ident,
-        selflike_args: ThinVec<P<Expr>>,
+        mut selflike_args: ThinVec<P<Expr>>,
         nonselflike_args: &[P<Expr>],
     ) -> BlockOrExpr {
+        assert!(
+            !selflike_args.is_empty(),
+            "static methods must use `expand_static_enum_method_body`",
+        );
+
         let span = trait_.span;
         let variants = &enum_def.variants;
 
         // Traits that unify fieldless variants always use the tag(s).
         let unify_fieldless_variants =
             self.fieldless_variants_strategy == FieldlessVariantsStrategy::Unify;
 
-        // There is no sensible code to be generated for *any* deriving on a
-        // zero-variant enum. So we just generate a failing expression.
+        // For zero-variant enum, this function body is unreachable. Generate
+        // `match *self {}`. This produces machine code identical to `unsafe {
+        // core::intrinsics::unreachable() }` while being safe and stable.
         if variants.is_empty() {
-            return BlockOrExpr(ThinVec::new(), Some(deriving::call_unreachable(cx, span)));
+            selflike_args.truncate(1);
+            let match_arg = cx.expr_deref(span, selflike_args.pop().unwrap());
+            let match_arms = ThinVec::new();
+            let expr = cx.expr_match(span, match_arg, match_arms);
+            return BlockOrExpr(ThinVec::new(), Some(expr));
         }
 
         let prefixes = iter::once("__self".to_string())

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -2,7 +2,7 @@ use crate::FnCtxt;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
-use rustc_infer::traits::ObligationCauseCode;
+use rustc_infer::{infer::type_variable::TypeVariableOriginKind, traits::ObligationCauseCode};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_span::{self, symbol::kw, Span};
 use rustc_trait_selection::traits;
@@ -267,8 +267,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             type BreakTy = ty::GenericArg<'tcx>;
             fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> {
                 if let Some(origin) = self.0.type_var_origin(ty)
-                    && let rustc_infer::infer::type_variable::TypeVariableOriginKind::TypeParameterDefinition(_, def_id) =
-                        origin.kind
+                    && let TypeVariableOriginKind::TypeParameterDefinition(_, def_id) = origin.kind
                     && let generics = self.0.tcx.generics_of(self.1)
                     && let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id)
                     && let Some(subst) = ty::GenericArgs::identity_for_item(self.0.tcx, self.1)

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -163,7 +163,7 @@ fn fmt_printer<'a, 'tcx>(infcx: &'a InferCtxt<'tcx>, ns: Namespace) -> FmtPrinte
         let ty_vars = infcx_inner.type_variables();
         let var_origin = ty_vars.var_origin(ty_vid);
         if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) = var_origin.kind
-            && !var_origin.span.from_expansion()
+            && name != kw::SelfUpper && !var_origin.span.from_expansion()
         {
             let generics = infcx.tcx.generics_of(infcx.tcx.parent(def_id));
             let idx = generics.param_def_id_to_index(infcx.tcx, def_id).unwrap();

compiler/rustc_target/src/spec/mod.rs

@@ -1433,6 +1433,8 @@ supported_targets! {
     ("riscv64gc-unknown-linux-gnu", riscv64gc_unknown_linux_gnu),
     ("riscv64gc-unknown-linux-musl", riscv64gc_unknown_linux_musl),
 
+    ("sparc-unknown-none-elf", sparc_unknown_none_elf),
+
     ("loongarch64-unknown-none", loongarch64_unknown_none),
     ("loongarch64-unknown-none-softfloat", loongarch64_unknown_none_softfloat),
 

compiler/rustc_target/src/spec/sparc_unknown_none_elf.rs

@@ -0,0 +1,27 @@
+use crate::abi::Endian;
+use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub fn target() -> Target {
+    let options = TargetOptions {
+        linker_flavor: LinkerFlavor::Gnu(Cc::Yes, Lld::No),
+        linker: Some("sparc-elf-gcc".into()),
+        endian: Endian::Big,
+        cpu: "v7".into(),
+        abi: "elf".into(),
+        max_atomic_width: Some(32),
+        atomic_cas: true,
+        panic_strategy: PanicStrategy::Abort,
+        relocation_model: RelocModel::Static,
+        no_default_libraries: false,
+        emit_debug_gdb_scripts: false,
+        eh_frame_header: false,
+        ..Default::default()
+    };
+    Target {
+        data_layout: "E-m:e-p:32:32-i64:64-f128:64-n32-S64".into(),
+        llvm_target: "sparc-unknown-none-elf".into(),
+        pointer_width: 32,
+        arch: "sparc".into(),
+        options,
+    }
+}

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -2388,14 +2388,11 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             // If there is only one implementation of the trait, suggest using it.
                             // Otherwise, use a placeholder comment for the implementation.
                             let (message, impl_suggestion) = if non_blanket_impl_count == 1 {(
-                                "use the fully-qualified path to the only available implementation".to_string(),
+                                "use the fully-qualified path to the only available implementation",
                                 format!("<{} as ", self.tcx.type_of(impl_def_id).instantiate_identity())
-                            )} else {(
-                                format!(
-                                    "use a fully-qualified path to a specific available implementation ({} found)",
-                                    non_blanket_impl_count
-                                ),
-                                "</* self type */ as ".to_string()
+                            )} else {
+                                ("use a fully-qualified path to a specific available implementation",
+                                                                "</* self type */ as ".to_string()
                             )};
                             let mut suggestions = vec![(
                                 path.span.shrink_to_lo(),

src/doc/rustc/src/SUMMARY.md

@@ -39,6 +39,7 @@
     - [mipsisa\*r6\*-unknown-linux-gnu\*](platform-support/mips-release-6.md)
     - [nvptx64-nvidia-cuda](platform-support/nvptx64-nvidia-cuda.md)
     - [riscv32imac-unknown-xous-elf](platform-support/riscv32imac-unknown-xous-elf.md)
+    - [sparc-unknown-none-elf](./platform-support/sparc-unknown-none-elf.md)
     - [*-pc-windows-gnullvm](platform-support/pc-windows-gnullvm.md)
     - [\*-nto-qnx-\*](platform-support/nto-qnx.md)
     - [\*-unknown-netbsd\*](platform-support/netbsd.md)

src/doc/rustc/src/platform-support.md

@@ -176,6 +176,7 @@ target | std | notes
 `thumbv8m.base-none-eabi` | * | Bare ARMv8-M Baseline
 `thumbv8m.main-none-eabi` | * | Bare ARMv8-M Mainline
 `thumbv8m.main-none-eabihf` | * | Bare ARMv8-M Mainline, hardfloat
+[`sparc-unknown-none-elf`](./platform-support/sparc-unknown-none-elf.md) | * | Bare 32-bit SPARC V7+
 `wasm32-unknown-emscripten` | ✓ | WebAssembly via Emscripten
 `wasm32-unknown-unknown` | ✓ | WebAssembly
 `wasm32-wasi` | ✓ | WebAssembly with WASI

src/doc/rustc/src/platform-support/sparc-unknown-none-elf.md

@@ -0,0 +1,164 @@
+# `sparc-unknown-none-elf`
+
+**Tier: 3**
+
+Rust for bare-metal 32-bit SPARC V7 and V8 systems, e.g. the Gaisler LEON3.
+
+| Target                 | Descriptions                              |
+| ---------------------- | ----------------------------------------- |
+| sparc-unknown-none-elf | SPARC V7 32-bit (freestanding, hardfloat) |
+
+## Target maintainers
+
+- Jonathan Pallant, <[email protected]>, https://ferrous-systems.com
+
+## Requirements
+
+This target is cross-compiled. There is no support for `std`. There is no
+default allocator, but it's possible to use `alloc` by supplying an allocator.
+
+This allows the generated code to run in environments, such as kernels, which
+may need to avoid the use of such registers or which may have special
+considerations about the use of such registers (e.g. saving and restoring them
+to avoid breaking userspace code using the same registers). You can change code
+generation to use additional CPU features via the `-C target-feature=` codegen
+options to rustc, or via the `#[target_feature]` mechanism within Rust code.
+
+By default, code generated with this target should run on any `SPARC` hardware;
+enabling additional target features may raise this baseline.
+
+- `-Ctarget-cpu=v8` adds the extra SPARC V8 instructions.
+
+- `-Ctarget-cpu=leon3` adds the SPARC V8 instructions and sets up scheduling to
+  suit the Gaisler Leon3.
+
+Functions marked `extern "C"` use the [standard SPARC architecture calling
+convention](https://sparc.org/technical-documents/).
+
+This target generates ELF binaries. Any alternate formats or special
+considerations for binary layout will require linker options or linker scripts.
+
+## Building the target
+
+You can build Rust with support for the target by adding it to the `target`
+list in `config.toml`:
+
+```toml
+[build]
+build-stage = 1
+target = ["sparc-unknown-none-elf"]
+```
+
+## Building Rust programs
+
+```text
+cargo build --target sparc-unknown-none-elf
+```
+
+This target uses GCC as a linker, and so you will need an appropriate GCC
+compatible `sparc-unknown-none` toolchain.
+
+The default linker name is `sparc-elf-gcc`, but you can override this in your
+project configuration.
+
+## Testing
+
+As `sparc-unknown-none-elf` supports a variety of different environments and does
+not support `std`, this target does not support running the Rust test suite.
+
+## Cross-compilation toolchains and C code
+
+This target was initially tested using [BCC2] from Gaisler, along with the TSIM
+Leon3 processor simulator. Both [BCC2] GCC and [BCC2] Clang have been shown to
+work. To work with these tools, your project configuration should contain
+something like:
+
+[BCC2]: https://www.gaisler.com/index.php/downloads/compilers
+
+`.cargo/config.toml`:
+```toml
+[target.sparc-unknown-none-elf]
+linker = "sparc-gaisler-elf-gcc"
+runner = "tsim-leon3"
+
+[build]
+target = ["sparc-unknown-none-elf"]
+rustflags = "-Ctarget-cpu=leon3"
+
+[unstable]
+build-std = ["core"]
+```
+
+With this configuration, running `cargo run` will compile your code for the
+SPARC V8 compatible Gaisler Leon3 processor and then start the `tsim-leon3`
+simulator. Once the simulator is running, simply enter the command
+`run` to start the code executing in the simulator.
+
+The default C toolchain libraries are linked in, so with the Gaisler [BCC2]
+toolchain, and using its default Leon3 BSP, you can use call the C `putchar`
+function and friends to output to the simulator console.
+
+Here's a complete example:
+
+```rust,ignore (cannot-test-this-because-it-assumes-special-libc-functions)
+#![no_std]
+#![no_main]
+
+extern "C" {
+    fn putchar(ch: i32);
+    fn _exit(code: i32) -> !;
+}
+
+#[no_mangle]
+extern "C" fn main() -> i32 {
+    let message = "Hello, this is Rust!";
+    for b in message.bytes() {
+        unsafe {
+            putchar(b as i32);
+        }
+    }
+    0
+}
+
+#[panic_handler]
+fn panic(_panic: &core::panic::PanicInfo) -> ! {
+    unsafe {
+        _exit(1);
+    }
+}
+```
+
+```console
+$ cargo run --target=sparc-unknown-none-elf
+   Compiling sparc-demo-rust v0.1.0 (/work/sparc-demo-rust)
+    Finished dev [unoptimized + debuginfo] target(s) in 3.44s
+     Running `tsim-leon3 target/sparc-unknown-none-elf/debug/sparc-demo-rust`
+
+ TSIM3 LEON3 SPARC simulator, version 3.1.9 (evaluation version)
+
+ Copyright (C) 2023, Frontgrade Gaisler - all rights reserved.
+ This software may only be used with a valid license.
+ For latest updates, go to https://www.gaisler.com/
+ Comments or bug-reports to [email protected]
+
+ This TSIM evaluation version will expire 2023-11-28
+
+Number of CPUs: 2
+system frequency: 50.000 MHz
+icache: 1 * 4 KiB, 16 bytes/line (4 KiB total)
+dcache: 1 * 4 KiB, 16 bytes/line (4 KiB total)
+Allocated 8192 KiB SRAM memory, in 1 bank at 0x40000000
+Allocated 32 MiB SDRAM memory, in 1 bank at 0x60000000
+Allocated 8192 KiB ROM memory at 0x00000000
+section: .text, addr: 0x40000000, size: 20528 bytes
+section: .rodata, addr: 0x40005030, size: 128 bytes
+section: .data, addr: 0x400050b0, size: 1176 bytes
+read 347 symbols
+
+tsim> run
+  Initializing and starting from 0x40000000
+Hello, this is Rust!
+
+  Program exited normally on CPU 0.
+tsim>
+```

src/doc/rustdoc/src/what-is-rustdoc.md

@@ -37,7 +37,7 @@ top, with no contents.
 ## Configuring rustdoc
 
 There are two problems with this: first, why does it
-think that our package is named "lib"? Second, why does it not have any
+think that our crate is named "lib"? Second, why does it not have any
 contents?
 
 The first problem is due to `rustdoc` trying to be helpful; like `rustc`,

src/tools/build-manifest/src/main.rs

@@ -127,6 +127,7 @@ static TARGETS: &[&str] = &[
     "s390x-unknown-linux-gnu",
     "sparc64-unknown-linux-gnu",
     "sparcv9-sun-solaris",
+    "sparc-unknown-none-elf",
     "thumbv6m-none-eabi",
     "thumbv7em-none-eabi",
     "thumbv7em-none-eabihf",

tests/ui/deriving/deriving-all-codegen.stdout

@@ -798,24 +798,22 @@ impl ::core::marker::Copy for Enum0 { }
 #[automatically_derived]
 impl ::core::fmt::Debug for Enum0 {
     fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
-        unsafe { ::core::intrinsics::unreachable() }
+        match *self {}
     }
 }
 #[automatically_derived]
 impl ::core::hash::Hash for Enum0 {
     #[inline]
     fn hash<__H: ::core::hash::Hasher>(&self, state: &mut __H) -> () {
-        unsafe { ::core::intrinsics::unreachable() }
+        match *self {}
     }
 }
 #[automatically_derived]
 impl ::core::marker::StructuralPartialEq for Enum0 { }
 #[automatically_derived]
 impl ::core::cmp::PartialEq for Enum0 {
     #[inline]
-    fn eq(&self, other: &Enum0) -> bool {
-        unsafe { ::core::intrinsics::unreachable() }
-    }
+    fn eq(&self, other: &Enum0) -> bool { match *self {} }
 }
 #[automatically_derived]
 impl ::core::marker::StructuralEq for Enum0 { }
@@ -831,15 +829,13 @@ impl ::core::cmp::PartialOrd for Enum0 {
     #[inline]
     fn partial_cmp(&self, other: &Enum0)
         -> ::core::option::Option<::core::cmp::Ordering> {
-        unsafe { ::core::intrinsics::unreachable() }
+        match *self {}
     }
 }
 #[automatically_derived]
 impl ::core::cmp::Ord for Enum0 {
     #[inline]
-    fn cmp(&self, other: &Enum0) -> ::core::cmp::Ordering {
-        unsafe { ::core::intrinsics::unreachable() }
-    }
+    fn cmp(&self, other: &Enum0) -> ::core::cmp::Ordering { match *self {} }
 }
 
 // A single-variant enum.

tests/ui/error-codes/E0283.stderr

@@ -7,7 +7,7 @@ LL |     fn create() -> u32;
 LL |     let cont: u32 = Generator::create();
    |                     ^^^^^^^^^^^^^^^^^ cannot call associated function of trait
    |
-help: use a fully-qualified path to a specific available implementation (2 found)
+help: use a fully-qualified path to a specific available implementation
    |
 LL |     let cont: u32 = </* self type */ as Generator>::create();
    |                     +++++++++++++++++++          +

tests/ui/error-codes/E0790.stderr

@@ -63,7 +63,7 @@ LL |     fn my_fn();
 LL |     MyTrait2::my_fn();
    |     ^^^^^^^^^^^^^^^ cannot call associated function of trait
    |
-help: use a fully-qualified path to a specific available implementation (2 found)
+help: use a fully-qualified path to a specific available implementation
    |
 LL |     </* self type */ as MyTrait2>::my_fn();
    |     +++++++++++++++++++         +

tests/ui/inference/need_type_info/infer-var-for-self-param.rs

@@ -0,0 +1,7 @@
+// Regression test for #113610 where we ICEd when trying to print
+// inference variables created by instantiating the self type parameter.
+
+fn main() {
+    let _ = (Default::default(),);
+    //~^ ERROR cannot call associated function on trait
+}