add build.zig API for linking against libstdc++ #3936
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standard library
This issue involves writing Zig code for the standard library.
zig build system
std.Build, the build runner, `zig build` subcommand, package management
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|
Yeah you need libstdc++ to the linker. I think we should have a build.zig API to support this use case; trying to link libstdc++ is pretty common, and is relevant for #853. In the meantime, your best bet is probably looking at zig's own build.zig script, because the self-hosted compiler must link libstdc++. |
andrewrk
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Thanks for the pointers! I got a workaround working with the following code in my build script: pub fn build(b: *Builder) !void {
// snip
try linkStdCpp(b, exe, ctx);
// snip
}
const LibraryDep = struct {
prefix: []const u8,
libdirs: ArrayList([]const u8),
libs: ArrayList([]const u8),
system_libs: ArrayList([]const u8),
includes: ArrayList([]const u8),
};
const Context = struct {
cmake_binary_dir: []const u8,
cxx_compiler: []const u8,
llvm_config_exe: []const u8,
lld_include_dir: []const u8,
lld_libraries: []const u8,
dia_guids_lib: []const u8,
llvm: LibraryDep,
};
fn findLLVM(b: *Builder, llvm_config_exe: []const u8) !LibraryDep {
const shared_mode = try b.exec(&[_][]const u8{ llvm_config_exe, "--shared-mode" });
const is_static = mem.startsWith(u8, shared_mode, "static");
const libs_output = if (is_static)
try b.exec(&[_][]const u8{
llvm_config_exe,
"--libfiles",
"--system-libs",
})
else
try b.exec(&[_][]const u8{
llvm_config_exe,
"--libs",
});
const includes_output = try b.exec(&[_][]const u8{ llvm_config_exe, "--includedir" });
const libdir_output = try b.exec(&[_][]const u8{ llvm_config_exe, "--libdir" });
const prefix_output = try b.exec(&[_][]const u8{ llvm_config_exe, "--prefix" });
var result = LibraryDep{
.prefix = mem.tokenize(prefix_output, " \r\n").next().?,
.libs = ArrayList([]const u8).init(b.allocator),
.system_libs = ArrayList([]const u8).init(b.allocator),
.includes = ArrayList([]const u8).init(b.allocator),
.libdirs = ArrayList([]const u8).init(b.allocator),
};
{
var it = mem.tokenize(libs_output, " \r\n");
while (it.next()) |lib_arg| {
if (mem.startsWith(u8, lib_arg, "-l")) {
try result.system_libs.append(lib_arg[2..]);
} else {
if (fs.path.isAbsolute(lib_arg)) {
try result.libs.append(lib_arg);
} else {
if (mem.endsWith(u8, lib_arg, ".lib")) {
lib_arg = lib_arg[0 .. lib_arg.len - 4];
}
try result.system_libs.append(lib_arg);
}
}
}
}
{
var it = mem.tokenize(includes_output, " \r\n");
while (it.next()) |include_arg| {
if (mem.startsWith(u8, include_arg, "-I")) {
try result.includes.append(include_arg[2..]);
} else {
try result.includes.append(include_arg);
}
}
}
{
var it = mem.tokenize(libdir_output, " \r\n");
while (it.next()) |libdir| {
if (mem.startsWith(u8, libdir, "-L")) {
try result.libdirs.append(libdir[2..]);
} else {
try result.libdirs.append(libdir);
}
}
}
return result;
}
fn nextValue(index: *usize, build_info: []const u8) []const u8 {
const start = index.*;
while (true) : (index.* += 1) {
switch (build_info[index.*]) {
'\n' => {
const result = build_info[start..index.*];
index.* += 1;
return result;
},
'\r' => {
const result = build_info[start..index.*];
index.* += 2;
return result;
},
else => continue,
}
}
}
fn getContext(b: *Builder) !Context {
// find the stage0 build artifacts because we're going to re-use config.h and zig_cpp library
const build_info = try b.exec(&[_][]const u8{
b.zig_exe,
"BUILD_INFO",
});
var index: usize = 0;
var ctx = Context{
.cmake_binary_dir = nextValue(&index, build_info),
.cxx_compiler = nextValue(&index, build_info),
.llvm_config_exe = nextValue(&index, build_info),
.lld_include_dir = nextValue(&index, build_info),
.lld_libraries = nextValue(&index, build_info),
.dia_guids_lib = nextValue(&index, build_info),
.llvm = undefined,
};
ctx.llvm = try findLLVM(b, ctx.llvm_config_exe);
return ctx;
}
fn linkStdCpp(b: *Builder, exe: var, ctx: Context) !void {
if (exe.target.getOs() == .linux) {
try addCxxKnownPath(b, ctx, exe, "libstdc++.a",
\\Unable to determine path to libstdc++.a
\\On Fedora, install libstdc++-static and try again.
);
exe.linkSystemLibrary("pthread");
} else if (exe.target.isFreeBSD()) {
try addCxxKnownPath(b, ctx, exe, "libc++.a", null);
exe.linkSystemLibrary("pthread");
} else if (exe.target.isDarwin()) {
if (addCxxKnownPath(b, ctx, exe, "libgcc_eh.a", "")) {
// Compiler is GCC.
try addCxxKnownPath(b, ctx, exe, "libstdc++.a", null);
exe.linkSystemLibrary("pthread");
// TODO LLD cannot perform this link.
// See https://github.com/ziglang/zig/issues/1535
exe.enableSystemLinkerHack();
} else |err| switch (err) {
error.RequiredLibraryNotFound => {
// System compiler, not gcc.
exe.linkSystemLibrary("c++");
},
else => return err,
}
}
if (ctx.dia_guids_lib.len != 0) {
exe.addObjectFile(ctx.dia_guids_lib);
}
exe.linkSystemLibrary("c");
}
fn addCxxKnownPath(
b: *Builder,
ctx: Context,
exe: var,
objname: []const u8,
errtxt: ?[]const u8,
) !void {
const path_padded = try b.exec(&[_][]const u8{
ctx.cxx_compiler,
b.fmt("-print-file-name={}", objname),
});
const path_unpadded = mem.tokenize(path_padded, "\r\n").next().?;
if (mem.eql(u8, path_unpadded, objname)) {
if (errtxt) |msg| {
warn("{}", msg);
} else {
warn("Unable to determine path to {}\n", objname);
}
return error.RequiredLibraryNotFound;
}
exe.addObjectFile(path_unpadded);
} |
|
Related: #4682 |
Is this still planned? |
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I'm attempting to build a project which links in the hyperscan regex library. The
build.zigscript links to the hyperscan library and I have a zig source file which includes the hyperscan header file in a@cImportblock. However, when I attempt to build the project withzig build, I get this error message:My hunch is that the remedy would involve using
libstdc++by passing in--stdlib=libc++or something similar to clang; however, I'm not sure if this is correct, and even if it was, there's no way to pass arbitrary flags to clang via thezigcli or abuild.zigfile, as far as I can tell.The text was updated successfully, but these errors were encountered: