Auto merge of rust-lang#110214 - compiler-errors:rollup-mkig4t6, r=compiler-errors

Rollup of 10 pull requests

Successful merges:

 - rust-lang#96971 (Initial support for loongarch64-unknown-linux-gnu)
 - rust-lang#109894 (Remove Errors section from var_os docs)
 - rust-lang#110000 (Rename tests/ui/unique to tests/ui/box/unit)
 - rust-lang#110018 (Pass host linker to compiletest.)
 - rust-lang#110104 ( Reword the docstring in todo! macro definition, fixing a typo)
 - rust-lang#110113 (Fix `x test ui --target foo` when download-rustc is enabled)
 - rust-lang#110126 (Support safe transmute in new solver)
 - rust-lang#110155 (Fix typos in librustdoc, tools and config files)
 - rust-lang#110162 (rustdoc: remove redundant expandSection code from main.js)
 - rust-lang#110173 (kmc-solid: Implement `Socket::read_buf`)

Failed merges:

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

Author: bors

compiler/rustc_codegen_gcc/example/alloc_system.rs

@@ -15,6 +15,7 @@
 const MIN_ALIGN: usize = 8;
 #[cfg(any(target_arch = "x86_64",
               target_arch = "aarch64",
+              target_arch = "loongarch64",
               target_arch = "mips64",
               target_arch = "s390x",
               target_arch = "sparc64"))]

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -127,6 +127,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
         "msp430" => Architecture::Msp430,
         "hexagon" => Architecture::Hexagon,
         "bpf" => Architecture::Bpf,
+        "loongarch64" => Architecture::LoongArch64,
         // Unsupported architecture.
         _ => return None,
     };
@@ -190,6 +191,10 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
             }
             e_flags
         }
+        Architecture::LoongArch64 => {
+            // Source: https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_e_flags_identifies_abi_type_and_version
+            elf::EF_LARCH_OBJABI_V1 | elf::EF_LARCH_ABI_DOUBLE_FLOAT
+        }
         _ => 0,
     };
     // adapted from LLVM's `MCELFObjectTargetWriter::getOSABI`

compiler/rustc_llvm/build.rs

@@ -10,6 +10,7 @@ const OPTIONAL_COMPONENTS: &[&str] = &[
     "aarch64",
     "amdgpu",
     "avr",
+    "loongarch",
     "m68k",
     "mips",
     "powerpc",

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -146,6 +146,12 @@ extern "C" void LLVMTimeTraceProfilerFinish(const char* FileName) {
 #define SUBTARGET_HEXAGON
 #endif
 
+#ifdef LLVM_COMPONENT_LOONGARCH
+#define SUBTARGET_LOONGARCH SUBTARGET(LoongArch)
+#else
+#define SUBTARGET_LOONGARCH
+#endif
+
 #define GEN_SUBTARGETS                                                         \
   SUBTARGET_X86                                                                \
   SUBTARGET_ARM                                                                \
@@ -159,6 +165,7 @@ extern "C" void LLVMTimeTraceProfilerFinish(const char* FileName) {
   SUBTARGET_SPARC                                                              \
   SUBTARGET_HEXAGON                                                            \
   SUBTARGET_RISCV                                                              \
+  SUBTARGET_LOONGARCH                                                          \
 
 #define SUBTARGET(x)                                                           \
   namespace llvm {                                                             \

compiler/rustc_llvm/src/lib.rs

@@ -102,6 +102,14 @@ pub fn initialize_available_targets() {
         LLVMInitializeM68kAsmPrinter,
         LLVMInitializeM68kAsmParser
     );
+    init_target!(
+        llvm_component = "loongarch",
+        LLVMInitializeLoongArchTargetInfo,
+        LLVMInitializeLoongArchTarget,
+        LLVMInitializeLoongArchTargetMC,
+        LLVMInitializeLoongArchAsmPrinter,
+        LLVMInitializeLoongArchAsmParser
+    );
     init_target!(
         llvm_component = "mips",
         LLVMInitializeMipsTargetInfo,

compiler/rustc_middle/src/ty/visit.rs

@@ -83,6 +83,9 @@ pub trait TypeVisitableExt<'tcx>: TypeVisitable<TyCtxt<'tcx>> {
                 | TypeFlags::HAS_CT_PLACEHOLDER,
         )
     }
+    fn has_non_region_placeholders(&self) -> bool {
+        self.has_type_flags(TypeFlags::HAS_TY_PLACEHOLDER | TypeFlags::HAS_CT_PLACEHOLDER)
+    }
     fn needs_subst(&self) -> bool {
         self.has_type_flags(TypeFlags::NEEDS_SUBST)
     }

compiler/rustc_target/src/spec/loongarch64_unknown_linux_gnu.rs

@@ -0,0 +1,17 @@
+use crate::spec::{Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "loongarch64-unknown-linux-gnu".into(),
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".into(),
+        arch: "loongarch64".into(),
+        options: TargetOptions {
+            cpu: "generic".into(),
+            features: "+f,+d".into(),
+            llvm_abiname: "lp64d".into(),
+            max_atomic_width: Some(64),
+            ..super::linux_gnu_base::opts()
+        },
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -1021,6 +1021,7 @@ supported_targets! {
     ("x86_64-unknown-linux-gnux32", x86_64_unknown_linux_gnux32),
     ("i686-unknown-linux-gnu", i686_unknown_linux_gnu),
     ("i586-unknown-linux-gnu", i586_unknown_linux_gnu),
+    ("loongarch64-unknown-linux-gnu", loongarch64_unknown_linux_gnu),
     ("m68k-unknown-linux-gnu", m68k_unknown_linux_gnu),
     ("mips-unknown-linux-gnu", mips_unknown_linux_gnu),
     ("mips64-unknown-linux-gnuabi64", mips64_unknown_linux_gnuabi64),

compiler/rustc_trait_selection/src/solve/assembly/mod.rs

@@ -225,6 +225,11 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<TyCtxt<'tcx>> + Copy + Eq {
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_transmute_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx>;
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
@@ -373,6 +378,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             G::consider_builtin_discriminant_kind_candidate(self, goal)
         } else if lang_items.destruct_trait() == Some(trait_def_id) {
             G::consider_builtin_destruct_candidate(self, goal)
+        } else if lang_items.transmute_trait() == Some(trait_def_id) {
+            G::consider_builtin_transmute_candidate(self, goal)
         } else {
             Err(NoSolution)
         };

compiler/rustc_trait_selection/src/solve/eval_ctxt.rs

@@ -639,4 +639,25 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         crate::traits::wf::unnormalized_obligations(self.infcx, param_env, arg)
             .map(|obligations| obligations.into_iter().map(|obligation| obligation.into()))
     }
+
+    pub(super) fn is_transmutable(
+        &self,
+        src_and_dst: rustc_transmute::Types<'tcx>,
+        scope: Ty<'tcx>,
+        assume: rustc_transmute::Assume,
+    ) -> Result<Certainty, NoSolution> {
+        // FIXME(transmutability): This really should be returning nested goals for `Answer::If*`
+        match rustc_transmute::TransmuteTypeEnv::new(self.infcx).is_transmutable(
+            ObligationCause::dummy(),
+            ty::Binder::dummy(src_and_dst),
+            scope,
+            assume,
+        ) {
+            rustc_transmute::Answer::Yes => Ok(Certainty::Yes),
+            rustc_transmute::Answer::No(_)
+            | rustc_transmute::Answer::IfTransmutable { .. }
+            | rustc_transmute::Answer::IfAll(_)
+            | rustc_transmute::Answer::IfAny(_) => Err(NoSolution),
+        }
+    }
 }