add fallback body to box_new intrinsic

[Vrtgs]

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[rustbot]

r? @Mark-Simulacrum

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[rust-log-analyzer]

The job aarch64-gnu-llvm-19-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [run-make] tests/run-make/alloc-no-oom-handling stdout ----

error: rmake recipe failed to complete
status: exit status: 1
command: cd "/checkout/obj/build/aarch64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out" && env -u RUSTFLAGS AR="ar" BUILD_ROOT="/checkout/obj/build/aarch64-unknown-linux-gnu" CARGO="/checkout/obj/build/aarch64-unknown-linux-gnu/stage1-tools-bin/cargo" CC="cc" CC_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC" CXX="c++" CXX_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC" HOST_RUSTC_DYLIB_PATH="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/lib" LD_LIBRARY_PATH="/checkout/obj/build/aarch64-unknown-linux-gnu/bootstrap-tools/aarch64-unknown-linux-gnu/release/deps:/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/lib/rustlib/aarch64-unknown-linux-gnu/lib" LD_LIB_PATH_ENVVAR="LD_LIBRARY_PATH" LLVM_BIN_DIR="/usr/lib/llvm-19/bin" LLVM_COMPONENTS="aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils aggressiveinstcombine all all-targets amdgpu amdgpuasmparser amdgpucodegen amdgpudesc amdgpudisassembler amdgpuinfo amdgputargetmca amdgpuutils analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo cfguard codegen codegendata codegentypes core coroutines coverage debuginfobtf debuginfocodeview debuginfodwarf debuginfogsym debuginfologicalview debuginfomsf debuginfopdb demangle dlltooldriver dwarflinker dwarflinkerclassic dwarflinkerparallel dwp engine executionengine extensions filecheck frontenddriver frontendhlsl frontendoffloading frontendopenacc frontendopenmp fuzzercli fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo hipstdpar instcombine instrumentation interfacestub interpreter ipo irprinter irreader jitlink lanai lanaiasmparser lanaicodegen lanaidesc lanaidisassembler lanaiinfo libdriver lineeditor linker loongarch loongarchasmparser loongarchcodegen loongarchdesc loongarchdisassembler loongarchinfo lto m68k m68kasmparser m68kcodegen m68kdesc m68kdisassembler m68kinfo mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts objcopy object objectyaml option orcdebugging orcjit orcshared orctargetprocess passes perfjitevents powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo riscvtargetmca runtimedyld sandboxir scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target targetparser textapi textapibinaryreader transformutils ve veasmparser vecodegen vectorize vedesc vedisassembler veinfo webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo webassemblyutils windowsdriver windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info x86targetmca xcore xcorecodegen xcoredesc xcoredisassembler xcoreinfo xray xtensa xtensaasmparser xtensacodegen xtensadesc xtensadisassembler xtensainfo" LLVM_FILECHECK="/usr/lib/llvm-19/bin/FileCheck" NODE="/usr/bin/node" PYTHON="/usr/bin/python3" RUSTC="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" RUSTDOC="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustdoc" SOURCE_ROOT="/checkout" TARGET="aarch64-unknown-linux-gnu" TARGET_EXE_DYLIB_PATH="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/lib/rustlib/aarch64-unknown-linux-gnu/lib" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake"
stdout: none
--- stderr -------------------------------
command failed at line 14
Command { cmd: LD_LIBRARY_PATH="/checkout/obj/build/aarch64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out:/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/lib:/checkout/obj/build/aarch64-unknown-linux-gnu/bootstrap-tools/aarch64-unknown-linux-gnu/release/deps:/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/lib/rustlib/aarch64-unknown-linux-gnu/lib" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "-L" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out" "--edition" "2021" "-Dwarnings" "--crate-type" "rlib" "/checkout/library/alloc/src/lib.rs" "--cfg" "no_global_oom_handling" "--target=aarch64-unknown-linux-gnu", stdin_buf: None, stdin: None, stdout: None, stderr: None, drop_bomb: DropBomb { command: "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc", defused: true, armed_location: Location { file: "/checkout/tests/run-make/alloc-no-oom-handling/rmake.rs", line: 8, column: 5 } }, already_executed: true }
output status: `exit status: 1`
=== STDOUT ===



=== STDERR ===
error[E0599]: no function or associated item named `new_uninit` found for struct `Box<_, _>` in the current scope
##[error]   --> /checkout/library/alloc/src/boxed.rs:243:21
    |
231 | / pub struct Box<
232 | |     T: ?Sized,
233 | |     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
234 | | >(Unique<T>, A);
    | |_- function or associated item `new_uninit` not found for this struct
...
243 |       Box::write(Box::new_uninit(), x)
    |                       ^^^^^^^^^^ function or associated item not found in `Box<_, _>`
    |
note: if you're trying to build a new `Box<_, _>` consider using one of the following associated functions:
      Box::<T>::try_new
      Box::<T>::try_new_uninit
      Box::<T>::try_new_zeroed
      Box::<T, A>::try_new_in
      and 12 others
   --> /checkout/library/alloc/src/boxed.rs:342:5
    |
342 |       pub fn try_new(x: T) -> Result<Self, AllocError> {
    |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
365 |       pub fn try_new_uninit() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
    |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
391 |       pub fn try_new_zeroed() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
    |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
440 | /     pub fn try_new_in(x: T, alloc: A) -> Result<Self, AllocError>
441 | |     where
442 | |         A: Allocator,
    | |_____________________^
help: there is an associated function `try_new_uninit` with a similar name
    |

[compiler-errors]

What is the motivation for this change? This intrinsic should be handled by MIR lowering and turned into a MIR statement, and shouldn't need a fallback body.

[compiler-errors]

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[Vrtgs]

What is the motivation for this change? This intrinsic should be handled by MIR lowering and turned into a MIR statement, and shouldn't need a fallback body.

I'm sorry but I didn't find anything in mir lowering (and still can't)
so I thought this was truly a compiler intrinsic, the motivation was adding more intrinsic fallbacks so that its easier to write a backend