`include/GFp/type_check.h:71:42: error: static assertion failed: "uint64_t is insufficient precision for n0"` when cross-compiling from `x86_64-unknown-linux-gnu` to `i686-unknown-linux-musl`

[indygreg]

If I attempt to cross-compile from an x86-64 Linux host to a i686-unknown-linux-musl target using Ubuntu 21.04, I get the following error:

$ cargo build --target i686-unknown-linux-musl
   Compiling ring v0.16.20 (/home/gps/src/ring)
error: failed to run custom build command for `ring v0.16.20 (/home/gps/src/ring)`

Caused by:
  process didn't exit successfully: `/home/gps/src/ring/target/debug/build/ring-dd912a5a5627170e/build-script-build` (exit code: 101)
  --- stdout
  OPT_LEVEL = Some("0")
  TARGET = Some("i686-unknown-linux-musl")
  HOST = Some("x86_64-unknown-linux-gnu")
  CC_i686-unknown-linux-musl = None
  CC_i686_unknown_linux_musl = None
  TARGET_CC = None
  CC = None
  CROSS_COMPILE = None
  CFLAGS_i686-unknown-linux-musl = None
  CFLAGS_i686_unknown_linux_musl = None
  TARGET_CFLAGS = None
  CFLAGS = None
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("true")
  CARGO_CFG_TARGET_FEATURE = Some("aes,avx,avx2,bmi1,bmi2,fma,fxsr,lzcnt,pclmulqdq,popcnt,rdrand,rdseed,sha,sse,sse2,sse3,sse4.1,sse4.2,ssse3,xsave,xsavec,xsaveopt,xsaves")
  IN_RUSSIA_NSA_WATCHES_YOU = true

  --- stderr
  running "musl-gcc" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-g" "-fno-omit-frame-pointer" "-m32" "-march=i686" "-Wl,-melf_i386" "-I" "include" "-Wall" "-Wextra" "-std=c1x" "-Wbad-function-cast" "-Wnested-externs" "-Wstrict-prototypes" "-pedantic" "-pedantic-errors" "-Wall" "-Wextra" "-Wcast-align" "-Wcast-qual" "-Wconversion" "-Wenum-compare" "-Wfloat-equal" "-Wformat=2" "-Winline" "-Winvalid-pch" "-Wmissing-field-initializers" "-Wmissing-include-dirs" "-Wredundant-decls" "-Wshadow" "-Wsign-compare" "-Wsign-conversion" "-Wundef" "-Wuninitialized" "-Wwrite-strings" "-fno-strict-aliasing" "-fvisibility=hidden" "-fstack-protector" "-g3" "-Werror" "-U_FORTIFY_SOURCE" "-c" "-o/home/gps/src/ring/target/i686-unknown-linux-musl/debug/build/ring-9725b7fb12d666c7/out/montgomery.o" "crypto/fipsmodule/bn/montgomery.c"
  In file included from crypto/fipsmodule/bn/montgomery.c:109:
  crypto/fipsmodule/bn/internal.h: In function ‘bn_umult_lohi’:
  crypto/fipsmodule/bn/internal.h:193:33: error: right shift count >= width of type [-Werror=shift-count-overflow]
    193 |   *high_out = (BN_ULONG)(result >> BN_BITS2);
        |                                 ^~
  In file included from crypto/fipsmodule/bn/montgomery.c:113:
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_adc’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:66:19: error: right shift count >= width of type [-Werror=shift-count-overflow]
     66 |   ret = (Carry)(x >> LIMB_BITS);
        |                   ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_add’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:80:19: error: right shift count >= width of type [-Werror=shift-count-overflow]
     80 |   ret = (Carry)(x >> LIMB_BITS);
        |                   ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_sbb’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:96:20: error: right shift count >= width of type [-Werror=shift-count-overflow]
     96 |   ret = (Carry)((x >> LIMB_BITS) & 1);
        |                    ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_sub’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:110:20: error: right shift count >= width of type [-Werror=shift-count-overflow]
    110 |   ret = (Carry)((x >> LIMB_BITS) & 1);
        |                    ^~
  In file included from include/GFp/base.h:59,
                   from crypto/fipsmodule/bn/internal.h:126,
                   from crypto/fipsmodule/bn/montgomery.c:109:
  crypto/fipsmodule/bn/montgomery.c: At top level:
  include/GFp/type_check.h:71:42: error: static assertion failed: "uint64_t is insufficient precision for n0"
     71 | #define OPENSSL_STATIC_ASSERT(cond, msg) _Static_assert(cond, msg)
        |                                          ^~~~~~~~~~~~~~
  crypto/fipsmodule/bn/montgomery.c:117:1: note: in expansion of macro ‘OPENSSL_STATIC_ASSERT’
    117 | OPENSSL_STATIC_ASSERT(
        | ^~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors
  thread 'main' panicked at 'execution failed', build.rs:718:9
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I can build ring fine in Docker images that have more flushed out musl toolchains that aren't as sensitive to cross-compiling issues. Most Rust crates can cross-compile to musl targets just fine. My guess is this C code / build system isn't sniffing out target features sufficiently.

This seems like a minor issue and is easy enough to workaround by switching build environments.

[briansmith]

Isn't the problem that you have musl-gcc installed but you don't have a musl toolchain (with musl headers) installed?

[briansmith]

right shift count >= width of type

This indicates to me that the musl headers you are using are 64 bit but the compiler is compiling in 32-bit mode.

[briansmith]

What you're doing probably works with clang but not GCC. See below:

    if (target.arch == "wasm32" && target.os == "unknown")
        || (target.os == "linux" && is_musl && target.arch != "x86_64")
    {
        if let Ok(compiler) = c.try_get_compiler() {
            // TODO: Expand this to non-clang compilers in 0.17.0 if practical.
            if compiler.is_like_clang() {
                let _ = c.flag("-nostdlibinc");
                let _ = c.define("RING_CORE_NOSTDLIBINC", "1");
            }
        }
    }

Does GCC support -nostdlibinc? Or does it support something that can do the same? If so, it would be great if you could submit a PR with something that works for GCC.

[briansmith]

@indygreg Did you get this working? Is this still an issue for you?

[jannic]

Just FYI, I have the same issue and didn't find a workaround yet. Not too important, I could just compile natively instead of cross-compiling. However, a proper solution would be more convenient. It seems like -nostdlibinc is not supported by gcc.

[jannic]

This looks like there is a fundamental problem with musl-gcc -m32.

Compiling this:

#include <stdint.h>
#include <assert.h>
static_assert(sizeof(uint32_t) == 4, "what???");
static_assert(sizeof(uint64_t) == 8, "what???");

With musl-gcc -m32 t.c results in:

t.c:4:1: error: static assertion failed: "what???"
 static_assert(sizeof(uint64_t) == 8, "what???");
 ^~~~~~~~~~~~~

It's no surprise that a 32bit uint64_t breaks things.

[briansmith]

It's no surprise that a 32bit uint64_t breaks things.

AFAICT, when this happens, this means that the headers are mismatched to what the compiler expects.

I have found that clang works much more reliably for cross-compiling than gcc.

If people think it is super important to support musl-gcc we could switch CI/CD to use musl-gcc instead of clang for this target, I guess.

[michaelherger]

Is there any way I could try to give clang a try?

[lnicola]

As a workaround, it kinda' works on Ubuntu 18.04, see https://github.com/briansmith/ring/issues/1507.

[peachkalemarsexpress]

I get a similar error and can't figure out how to solve it

 --- stdout
  OPT_LEVEL = Some("3")
  TARGET = Some("i686-unknown-linux-musl")
  HOST = Some("x86_64-unknown-linux-gnu")
  cargo:rerun-if-env-changed=CC_i686-unknown-linux-musl
  CC_i686-unknown-linux-musl = None
  cargo:rerun-if-env-changed=CC_i686_unknown_linux_musl
  CC_i686_unknown_linux_musl = None
  cargo:rerun-if-env-changed=TARGET_CC
  TARGET_CC = Some("musl-gcc")
  cargo:rerun-if-env-changed=CFLAGS_i686-unknown-linux-musl
  CFLAGS_i686-unknown-linux-musl = None
  cargo:rerun-if-env-changed=CFLAGS_i686_unknown_linux_musl
  CFLAGS_i686_unknown_linux_musl = None
  cargo:rerun-if-env-changed=TARGET_CFLAGS
  TARGET_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("false")
  CARGO_CFG_TARGET_FEATURE = Some("crt-static,fxsr,sse,sse2")

  --- stderr
  running "musl-gcc" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m32" "-static" "-march=i686" "-Wl,-melf_i386" "-I" "include" "-Wall" "-Wextra" "-std=c1x" "-Wbad-function-cast" "-Wnested-externs" "-Wstrict-prototypes" "-pedantic" "-pedantic-errors" "-Wall" "-Wextra" "-Wcast-align" "-Wcast-qual" "-Wconversion" "-Wenum-compare" "-Wfloat-equal" "-Wformat=2" "-Winline" "-Winvalid-pch" "-Wmissing-field-initializers" "-Wmissing-include-dirs" "-Wredundant-decls" "-Wshadow" "-Wsign-compare" "-Wsign-conversion" "-Wundef" "-Wuninitialized" "-Wwrite-strings" "-fno-strict-aliasing" "-fvisibility=hidden" "-fstack-protector" "-g3" "-U_FORTIFY_SOURCE" "-DNDEBUG" "-c" "-o/home/user/my_app/target/i686-unknown-linux-musl/release/build/ring-417329f1ff283af4/out/montgomery.o" "crypto/fipsmodule/bn/montgomery.c"
  In file included from crypto/fipsmodule/bn/montgomery.c:109:
  crypto/fipsmodule/bn/internal.h: In function ‘bn_umult_lohi’:
  crypto/fipsmodule/bn/internal.h:193:33: warning: right shift count >= width of type [-Wshift-count-overflow]
    193 |   *high_out = (BN_ULONG)(result >> BN_BITS2);
        |                                 ^~
  In file included from crypto/fipsmodule/bn/montgomery.c:113:
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_adc’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:66:19: warning: right shift count >= width of type [-Wshift-count-overflow]
     66 |   ret = (Carry)(x >> LIMB_BITS);
        |                   ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_add’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:80:19: warning: right shift count >= width of type [-Wshift-count-overflow]
     80 |   ret = (Carry)(x >> LIMB_BITS);
        |                   ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_sbb’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:96:20: warning: right shift count >= width of type [-Wshift-count-overflow]
     96 |   ret = (Carry)((x >> LIMB_BITS) & 1);
        |                    ^~
  crypto/fipsmodule/bn/../../limbs/limbs.inl: In function ‘limb_sub’:
  crypto/fipsmodule/bn/../../limbs/limbs.inl:110:20: warning: right shift count >= width of type [-Wshift-count-overflow]
    110 |   ret = (Carry)((x >> LIMB_BITS) & 1);
        |                    ^~
  In file included from include/GFp/base.h:59,
                   from crypto/fipsmodule/bn/internal.h:126:
  crypto/fipsmodule/bn/montgomery.c: At top level:
  include/GFp/type_check.h:71:42: error: static assertion failed: "uint64_t is insufficient precision for n0"
     71 | #define OPENSSL_STATIC_ASSERT(cond, msg) _Static_assert(cond, msg)
        |                                          ^~~~~~~~~~~~~~
  crypto/fipsmodule/bn/montgomery.c:117:1: note: in expansion of macro ‘OPENSSL_STATIC_ASSERT’
    117 | OPENSSL_STATIC_ASSERT(
        | ^~~~~~~~~~~~~~~~~~~~~
  thread 'main' panicked at 'execution failed', /home/user/.cargo/registry/src/github.com-1ecc6299db9ec823/ring-0.16.20/build.rs:656:9

I'm a bit new at this, so please forgive me. Really hoping for some help)