Can't cross-compile from Linux to i686-pc-windows-gnu

[YaLTeR]

c85616137a367a72367a7d3f6019a5816ee5aa7b, Fedora 35

┌ (master) ~/s/r/mlua
└─ env CFLAGS=-m32 LDFLAGS=-m32 cargo build --features=vendored,luajit --target=i686-pc-windows-gnu
   Compiling proc-macro2 v1.0.36
   Compiling unicode-xid v0.2.2
   Compiling syn v1.0.89
   Compiling serde_derive v1.0.136
   Compiling cc v1.0.73
   Compiling memchr v2.4.1
   Compiling autocfg v1.1.0
   Compiling serde v1.0.136
   Compiling pkg-config v0.3.24
   Compiling regex-automata v0.1.10
   Compiling lazy_static v1.4.0
   Compiling once_cell v1.10.0
   Compiling rustc-hash v1.1.0
   Compiling num-traits v0.2.14
   Compiling luajit-src v210.3.3+resty673aaad
   Compiling lua-src v544.0.0
   Compiling quote v1.0.15
   Compiling mlua v0.7.4 (/var/home/yalter/source/rs/mlua)
error: failed to run custom build command for `mlua v0.7.4 (/var/home/yalter/source/rs/mlua)`

Caused by:
  process didn't exit successfully: `/var/home/yalter/source/rs/mlua/target/debug/build/mlua-1be8cf42852d931a/build-script-main` (exit status: 101)
  --- stdout
  CC_i686-pc-windows-gnu = None
  CC_i686_pc_windows_gnu = None
  TARGET_CC = None
  CC = None
  CROSS_COMPILE = None
  CFLAGS_i686-pc-windows-gnu = None
  CFLAGS_i686_pc_windows_gnu = None
  TARGET_CFLAGS = None
  CFLAGS = Some("-m32")
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("true")
  CARGO_CFG_TARGET_FEATURE = Some("fxsr,sse,sse2")
  running "make" "-e"
  CC        lj_init.o
  HOSTCC    host/minilua.o
  HOSTLINK  host/minilua
  DYNASM    host/buildvm_arch.h
  HOSTCC    host/buildvm.o
  HOSTCC    host/buildvm_asm.o
  HOSTCC    host/buildvm_peobj.o
  HOSTCC    host/buildvm_lib.o
  HOSTCC    host/buildvm_fold.o
  HOSTLINK  host/buildvm
  BUILDVM   lj_vm.S
  ASM       lj_vm.o

  --- stderr
  buildvm_x86.dasc: Assembler messages:
  buildvm_x86.dasc:6: Error: unknown pseudo-op: `.hidden'
  buildvm_x86.dasc:7: Warning: .type pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:7: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:8: Warning: .size pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:8: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:13: Error: unknown pseudo-op: `.hidden'
  buildvm_x86.dasc:14: Warning: .type pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:14: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:15: Warning: .size pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:15: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:24: Error: unknown pseudo-op: `.hidden'
  buildvm_x86.dasc:25: Warning: .type pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:25: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:26: Warning: .size pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:26: Error: junk at end of line, first unrecognized character is `l'
(and so on)
  buildvm_x86.dasc:2628: Warning: .size pseudo-op used outside of .def/.endef: ignored.
  buildvm_x86.dasc:2628: Error: junk at end of line, first unrecognized character is `l'
  buildvm_x86.dasc:2636: Error: junk at end of line, first unrecognized character is `-'
  buildvm_x86.dasc:2639: Error: junk at end of line, first unrecognized character is `,'
  buildvm_x86.dasc:2693: Error: junk at end of line, first unrecognized character is `,'
  make: *** [Makefile:713: lj_vm.o] Error 1
  thread 'main' panicked at '
  Error building LuaJIT:
      Command: "make" "-e"
      Exit status: exit status: 2
      ', /var/home/yalter/.cargo/registry/src/github.com-1ecc6299db9ec823/luajit-src-210.3.3+resty673aaad/src/lib.rs:200:13
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: build failed

Without -m32 is fails even earlier for some reason.

[khvzak]

mlua uses LuaJIT build system. Can you reproduce this issue when compiling https://github.com/LuaJIT/LuaJIT v2.1 branch ? If yes, could you submit a bug report to LuaJIT please.

[YaLTeR]

According to LuaJIT's cross-compiling docs for this configuration you need to set TARGET_SYS=Windows. Compiling on my system using make HOST_CC="gcc -m32" CROSS=i686-w64-mingw32- TARGET_SYS=Windows worked fine, while compiling without TARGET_SYS=Windows resulted in the same errors as in this issue. I'm guessing luajit-src-rs needs to add TARGET_SYS=Windows when cross-compiling to Windows.

[YaLTeR]

FYI, even cross-compiling to 32-bit Linux doesn't work automatically in luajit-src-rs at the moment: you need to specify -m32 in CFLAGS and LDFLAGS manually. Would be nice if that worked out of the box too.

[YaLTeR]

I seem to have fixed the TARGET_OS=Windows problem in the above PR; the 32-bit problem seems to run a bit deeper.

1. cc returns i686-linux-gnu-gcc as the compiler, which is valid on Ubuntu but not on Fedora, so that needs to be figured out somehow
2. LuaJIT's docs recommend setting -m32 on CC and/or HOST_CC directly, which requires knowing a valid compiler, see 1.

I guess I'll just keep manually setting those variables for now, works well enough.

[khvzak]

Thanks, I'll try fix it (check your PR) before releasing 0.8.0 (non-beta)

[barsoosayque]

Can confirm this helps. Though, I'm compiling to x86_64. Currently just setting it through an environment variable as a workaround (together with TARGET_CC, TARGET_AR and TARGET_LD).

[khvzak]

It should be fixed in the new luajit-src 210.4.6+resty2cf5186