File format not recognized when linking rmeta file for sparc-linux-unknown-gnu

[glaubitz]

I am currently trying to build rustc for the sparc-linux-unknown-gnu target which fails with the linker complaining about not recognizing the file format of the rmeta file on the command line:

error: linking with `sparc-linux-gnu-gcc` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/bin:/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/bin:/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/bin:/home/glaubitz/.local/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games" VSLANG="1033" "sparc-linux-gnu-gcc" "-Wl,--version-script=/tmp/rustc9YiYtF/list" "-Wl,--no-undefined-version" "-mcpu=v9" "-m32" "-Wl,-melf32_sparc" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.00.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.01.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.02.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.03.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.04.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.05.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.06.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.07.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.08.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.09.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.10.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.11.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.12.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.13.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.14.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.std.a946a352528c9d3a-cgu.15.rcgu.o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.dn0tar95l4w690nusxeqr43d3.rcgu.rmeta" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.040sn9hd3kpadxvyhdk75ycx5.rcgu.o" "-Wl,--as-needed" "-L" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps" "-L" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/release/deps" "-L" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/build/compiler_builtins-9cbe5026186c715b/out" "-L" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/sparc-unknown-linux-gnu/lib" "-Wl,-Bstatic" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libpanic_unwind-d6f3e19e347e8e30.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libobject-96ad8f1969790b3e.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libmemchr-7d65095888af1252.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libaddr2line-bc5934419298e94f.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libgimli-a550d13df8702836.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/librustc_demangle-3a3f56a767e453f8.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libstd_detect-34ae8bef4a03fd18.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libhashbrown-46ce46b7ff78718c.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/librustc_std_workspace_alloc-738616e97bd712d8.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libminiz_oxide-1f2e9ed080496ac7.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libadler-c646151839979ca7.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libunwind-77b4a24e6c936276.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libcfg_if-ca580308d22018b6.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/liblibc-721c91ee08a9ebc2.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/liballoc-5364848951c68550.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/librustc_std_workspace_core-2d05bd64c8bcabbb.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libcore-e51655d4cadb2e75.rlib" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libcompiler_builtins-494aac20c9cb2b3e.rlib" "-Wl,-Bdynamic" "-lgcc_s" "-lutil" "-lrt" "-lpthread" "-lm" "-ldl" "-lc" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/sparc-unknown-linux-gnu/lib" "-o" "/home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/libstd-41da709e9f6744d7.so" "-shared" "-Wl,-z,relro,-z,now" "-Wl,-O1" "-nodefaultlibs" "-Wl,-z,origin" "-Wl,-rpath,$ORIGIN/../lib"
  = note: /home/glaubitz/rust/build/x86_64-unknown-linux-gnu/stage1-std/sparc-unknown-linux-gnu/release/deps/std-41da709e9f6744d7.dn0tar95l4w690nusxeqr43d3.rcgu.rmeta: file not recognized: file format not recognized
          collect2: error: ld returned 1 exit status

I have already tried tuning the compiler and linker options in compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs, but I am still getting the same error. Since I have no clue what the rmeta file is supposed to contain, I don't know what might be wrong and needs to be fixed.

Thus, opening an issue in the hope that someone can explain what's in the rmeta file and what could be the reason for that file containing unexpected information, so I can come up with a possible fix.

[glaubitz]

OK, this seems to be related about 32-bit SPARC missing an entry in compiler/rustc_codegen_ssa/src/back/metadata.rs.

But I have no clue where to find the source for the object crate.

@nikic Any suggestion?

[nikic]

@glaubitz The source for the object crate is at https://github.com/gimli-rs/object.

[glaubitz]

Thanks, I just found that as well ;-). Guess we need to add support for Sparc there to fix this bug.

[glaubitz]

OK, I just did a quick and dirty hack to verify my theory:

diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index 264a98844ad..8bbde747725 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -209,6 +209,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
         "powerpc64" => (Architecture::PowerPc64, None),
         "riscv32" => (Architecture::Riscv32, None),
         "riscv64" => (Architecture::Riscv64, None),
+        "sparc" => (Architecture::Sparc64, None),
         "sparc64" => (Architecture::Sparc64, None),
         "avr" => (Architecture::Avr, None),
         "msp430" => (Architecture::Msp430, None),

and indeed the rmeta file is now a 64-bit SPARC object file. Thus, adding 32-bit SPARC to the object crate will fix this bug.

[glaubitz]

@nikic So, I tried editing the object crate that is being used to build rustc_codegen_ssa, but I cannot find that copy anywhere. In the past, it used to be in ~/.cargo/ but that doesn't seem to be the case anymore.

Can you tell me how I can edit the object crate for testing my patch?

[nikic]

You should be able to use [patch] to specify a local version of the crate (https://doc.rust-lang.org/cargo/reference/overriding-dependencies.html#the-patch-section).

[glaubitz]

Thanks, that's very helpful! I didn't know about [patch].

[taiki-e]

I think this has been fixed by #128772 & #131222 & #132552.