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JuliaC --trim compatibility #507

Open
#508
Open
JuliaC --trim compatibility#507
#508
@langestefan

Description

@langestefan
langestefan
opened on Feb 17, 2026

TimeZones.jl is currently not compatible with JuliaC and the trim option.

MWE:

mwe_timezones.jl

module MWE

using TimeZones  # This is all it takes to trigger the crash

Base.@ccallable function hello()::Int32
    return Int32(42)
end

end

mwe_demo.c

#include <stdio.h>
#include <dlfcn.h>
#include <string.h>
#include <unistd.h>

typedef int (*hello_fn)(void);
static char lib_path[4096];

int main(void) {
    ssize_t len = readlink("/proc/self/exe", lib_path, sizeof(lib_path) - 1);
    lib_path[len] = '\0';
    char *s = strrchr(lib_path, '/');
    if (s) *(s + 1) = '\0';
    strcat(lib_path, "libmwe_timezones.so");

    void *h = dlopen(lib_path, RTLD_NOW | RTLD_GLOBAL);
    if (!h) { fprintf(stderr, "dlopen: %s\n", dlerror()); return 1; }

    hello_fn f = (hello_fn)dlsym(h, "hello");
    printf("hello() = %d\n", f());
    dlclose(h);
    return 0;
}

Build without trim, works fine

julia -e '
using JuliaC
img = ImageRecipe(output_type="--output-lib", file="mwe_timezones.jl",
                  trim_mode="no", add_ccallables=true, project=".")
link = LinkRecipe(image_recipe=img, outname="build_notrim/lib/libmwe_timezones")
bun = BundleRecipe(link_recipe=link, output_dir="build_notrim")
compile_products(img); link_products(link); bundle_products(bun)'

# Build and run C demo
gcc -o build_notrim/lib/mwe_demo mwe_demo.c -ldl
LD_LIBRARY_PATH=build_notrim/lib:build_notrim/lib/julia ./build_notrim/lib/mwe_demo
# Output: hello() = 42

Build with trim succeeds, running fails

julia -e '
using JuliaC
img = ImageRecipe(output_type="--output-lib", file="mwe_timezones.jl",
                  trim_mode="unsafe", add_ccallables=true, project=".")
link = LinkRecipe(image_recipe=img, outname="build_trim/lib/libmwe_timezones")
bun = BundleRecipe(link_recipe=link, output_dir="build_trim")
compile_products(img); link_products(link); bundle_products(bun)'

# Build and run C demo
gcc -o build_trim/lib/mwe_demo mwe_demo.c -ldl
LD_LIBRARY_PATH=build_trim/lib:build_trim/lib/julia ./build_trim/lib/mwe_demo
# Output: fatal: Core.InitError(mod=:TimeZones, error=Core.MethodError(f=Artifacts.var"#_artifact_str"()...))

The output is:

Output 
dlopen succeeded!
fatal: error thrown and no exception handler available.
Core.InitError(mod=:TimeZones, error=Core.MethodError(f=Artifacts.var"#_artifact_str"(), args=(TZJData, "/home/langestefan/.julia/packages/TZJData/gKErz/Artifacts.toml", Base.SubString{Core.String}(string="tzjdata", offset=0, ncodeunits=7), "", Base.Dict{Core.String, Any}(slots=Memory{Core.UInt8}(16, 0x7f87870b9040)[0x00, 0x00, 0xaa, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], keys=Memory{Core.String}(16, 0x7f878709dd90)[
  #<null>,
  #<null>,
  "tzjdata",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>], vals=Memory{Any}(16, 0x7f878709d900)[
  #<null>,
  #<null>,
  Base.Dict{Core.String, Any}(slots=Memory{Core.UInt8}(16, 0x7f87870b9010)[0x00, 0x00, 0x00, 0xdf, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x87, 0x00, 0x00, 0x00, 0x00, 0x00], keys=Memory{Core.String}(16, 0x7f878709dcc0)[
  #<null>,
  #<null>,
  #<null>,
  "git-tree-sha1",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "download",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>], vals=Memory{Any}(16, 0x7f878709d9f0)[
  #<null>,
  #<null>,
  #<null>,
  "a2939c302ec6f8c6eeb94e4734c96b162e1ff7b5",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  Array{Any, 1}(dims=(1,), mem=Memory{Any}(3, 0x7f878709dac0)[
  Base.Dict{Core.String, Any}(slots=Memory{Core.UInt8}(16, 0x7f87870b8f70)[0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd7, 0x00, 0x00], keys=Memory{Core.String}(16, 0x7f878709dbf0)[
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "sha256",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "url",
  #<null>,
  #<null>], vals=Memory{Any}(16, 0x7f878709db50)[
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "75d5f6bf78963b5362e46263a9493dc0d460a720eb5f468fdeb50a61dd63649d",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "https://github.com/JuliaTime/TZJData.jl/releases/download/v1.5.0+2025b/tzjfile-v1-tzdata2025b.tar.gz",
  #<null>,
  #<null>], ndel=0, count=2, age=0x0000000000000003, idxfloor=1, maxprobe=0),
  #<null>,
  #<null>]),
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>], ndel=0, count=2, age=0x0000000000000003, idxfloor=1, maxprobe=0),
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>], ndel=0, count=1, age=0x0000000000000002, idxfloor=1, maxprobe=0), Base.SHA1(bytes=(0xa2, 0x93, 0x9c, 0x30, 0x2e, 0xc6, 0xf8, 0xc6, 0xee, 0xb9, 0x4e, 0x47, 0x34, 0xc9, 0x6b, 0x16, 0x2e, 0x1f, 0xf7, 0xb5)), Base.BinaryPlatforms.Platform(tags=Base.Dict{Core.String, Core.String}(slots=Memory{Core.UInt8}(16, 0x7f87870b9330)[0x00, 0x00, 0xdd, 0x8d, 0xf7, 0x00, 0x00, 0x00, 0x00, 0xc5, 0x00, 0xe9, 0x00, 0x00, 0xb7, 0xea], keys=Memory{Core.String}(16, 0x7f878709e730)[
  #<null>,
  #<null>,
  "libgfortran_version",
  "arch",
  "julia_version",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "libc",
  #<null>,
  "libstdcxx_version",
  #<null>,
  #<null>,
  "os",
  "cxxstring_abi"], vals=Memory{Core.String}(16, 0x7f878709e690)[
  #<null>,
  #<null>,
  "5.0.0",
  "x86_64",
  "1.12.5",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "glibc",
  #<null>,
  "3.4.30",
  #<null>,
  #<null>,
  "linux",
  "cxx11"], ndel=0, count=7, age=0x0000000000000008, idxfloor=1, maxprobe=2), compare_strategies=Base.Dict{Core.String, Core.Function}(slots=Memory{Core.UInt8}(16, 0x7f87870b9120)[0x00, 0x00, 0xf7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe9, 0x00, 0x00, 0x00, 0x00], keys=Memory{Core.String}(16, 0x7f878709e460)[
  #<null>,
  #<null>,
  "julia_version",
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  #<null>,
  "libstdcxx_version",
  #<null>,
  #<null>,
  #<null>,
  #<null>], vals=Memory{Core.Function}(16, 0x7f878709dfd0)[#<null>, #<null>, Base.BinaryPlatforms.var"#4#5"(), #<null>, #<null>, #<null>, #<null>, #<null>, #<null>, #<null>, #<null>, Base.BinaryPlatforms.var"#compare_version_cap"(), #<null>, #<null>, #<null>, #<null>], ndel=0, count=2, age=0x0000000000000003, idxfloor=1, maxprobe=0)), Base.Val{Artifacts}()), world=0x0000000000009791))

Loading TimeZones.jl is enough to cause the failure.

My guess is that --trim removes Artifacts._artifact_str because it is unreachable from hello().

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