gnu: Add zig.

* gnu/packages/patches/zig-disable-libc-note-test.patch,
gnu/packages/patches/zig-use-system-paths.patch: New files.
* gnu/packages/zig.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES, dist_patch_DATA): Adjust accordingly.

2 files changed, 174 insertions, 0 deletions

diff --git a/gnu/packages/patches/zig-disable-libc-note-test.patch b/gnu/packages/patches/zig-disable-libc-note-test.patch
new file mode 100644
index 0000000000..4d76139efb
--- /dev/null
+++ b/gnu/packages/patches/zig-disable-libc-note-test.patch
@@ -0,0 +1,31 @@
+This test fails with "error.CompilationIncorrectlySucceeded".
+
+diff --git a/test/compile_errors.zig b/test/compile_errors.zig
+index fd1255c..20d5548 100644
+--- a/test/compile_errors.zig
++++ b/test/compile_errors.zig
+@@ -2751,15 +2751,15 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
+             "tmp.zig:3:5: error: dependency on libc must be explicitly specified in the build command",
+         });
+
+-        cases.addTest("libc headers note",
+-            \\const c = @cImport(@cInclude("stdio.h"));
+-            \\export fn entry() void {
+-            \\    _ = c.printf("hello, world!\n");
+-            \\}
+-        , &[_][]const u8{
+-            "tmp.zig:1:11: error: C import failed",
+-            "tmp.zig:1:11: note: libc headers not available; compilation does not link against libc",
+-        });
++//        cases.addTest("libc headers note",
++//            \\const c = @cImport(@cInclude("stdio.h"));
++//            \\export fn entry() void {
++//            \\    _ = c.printf("hello, world!\n");
++//            \\}
++//        , &[_][]const u8{
++//            "tmp.zig:1:11: error: C import failed",
++//            "tmp.zig:1:11: note: libc headers not available; compilation does not link against libc",
++//        });
+     }
+
+     cases.addTest("comptime vector overflow shows the index",
diff --git a/gnu/packages/patches/zig-use-system-paths.patch b/gnu/packages/patches/zig-use-system-paths.patch
new file mode 100644
index 0000000000..33b7da1e0d
--- /dev/null
+++ b/gnu/packages/patches/zig-use-system-paths.patch
@@ -0,0 +1,143 @@
+This patch replaces the OS-specific detection mechanism by one that solely
+relies on environment variables.  This has the benefit that said environment
+variables can be used as search paths in Guix.
+
+Index: zig-0.8.1/lib/std/zig/system.zig
+===================================================================
+--- zig-0.8.1.orig/lib/std/zig/system.zig
++++ zig-0.8.1/lib/std/zig/system.zig
+@@ -39,101 +39,57 @@ pub const NativePaths = struct {
+         };
+         errdefer self.deinit();
+
+-        var is_nix = false;
+-        if (process.getEnvVarOwned(allocator, "NIX_CFLAGS_COMPILE")) |nix_cflags_compile| {
+-            defer allocator.free(nix_cflags_compile);
+-
+-            is_nix = true;
+-            var it = mem.tokenize(nix_cflags_compile, " ");
++        // TODO: Support cross-compile paths?
++        if (process.getEnvVarOwned(allocator, "C_INCLUDE_PATH")) |c_include_path| {
++            defer allocator.free(c_include_path);
++            var it = mem.tokenize(c_include_path, ":");
+             while (true) {
+-                const word = it.next() orelse break;
+-                if (mem.eql(u8, word, "-isystem")) {
+-                    const include_path = it.next() orelse {
+-                        try self.addWarning("Expected argument after -isystem in NIX_CFLAGS_COMPILE");
+-                        break;
+-                    };
+-                    try self.addIncludeDir(include_path);
+-                } else {
+-                    if (mem.startsWith(u8, word, "-frandom-seed=")) {
+-                        continue;
+-                    }
+-                    try self.addWarningFmt("Unrecognized C flag from NIX_CFLAGS_COMPILE: {s}", .{word});
+-                }
++                const dir = it.next() orelse break;
++                try self.addIncludeDir(dir);
+             }
+         } else |err| switch (err) {
+             error.InvalidUtf8 => {},
+             error.EnvironmentVariableNotFound => {},
+             error.OutOfMemory => |e| return e,
+         }
+-        if (process.getEnvVarOwned(allocator, "NIX_LDFLAGS")) |nix_ldflags| {
+-            defer allocator.free(nix_ldflags);
+
+-            is_nix = true;
+-            var it = mem.tokenize(nix_ldflags, " ");
++        if (process.getEnvVarOwned(allocator, "CPLUS_INCLUDE_PATH")) |cplus_include_path| {
++            defer allocator.free(cplus_include_path);
++            var it = mem.tokenize(cplus_include_path, ":");
+             while (true) {
+-                const word = it.next() orelse break;
+-                if (mem.eql(u8, word, "-rpath")) {
+-                    const rpath = it.next() orelse {
+-                        try self.addWarning("Expected argument after -rpath in NIX_LDFLAGS");
+-                        break;
+-                    };
+-                    try self.addRPath(rpath);
+-                } else if (word.len > 2 and word[0] == '-' and word[1] == 'L') {
+-                    const lib_path = word[2..];
+-                    try self.addLibDir(lib_path);
+-                } else {
+-                    try self.addWarningFmt("Unrecognized C flag from NIX_LDFLAGS: {s}", .{word});
+-                    break;
+-                }
++                const dir = it.next() orelse break;
++                try self.addIncludeDir(dir);
+             }
+         } else |err| switch (err) {
+             error.InvalidUtf8 => {},
+             error.EnvironmentVariableNotFound => {},
+             error.OutOfMemory => |e| return e,
+         }
+-        if (is_nix) {
+-            return self;
+-        }
+-
+-        if (comptime Target.current.isDarwin()) {
+-            try self.addIncludeDir("/usr/include");
+-            try self.addIncludeDir("/usr/local/include");
+
+-            try self.addLibDir("/usr/lib");
+-            try self.addLibDir("/usr/local/lib");
+-
+-            try self.addFrameworkDir("/Library/Frameworks");
+-            try self.addFrameworkDir("/System/Library/Frameworks");
+-
+-            return self;
++        if (process.getEnvVarOwned(allocator, "LIBRARY_PATH")) |library_path| {
++            defer allocator.free(library_path);
++            var it = mem.tokenize(library_path, ":");
++            while (true) {
++                const dir = it.next() orelse break;
++                try self.addLibDir(dir);
++            }
++        } else |err| switch (err) {
++            error.InvalidUtf8 => {},
++            error.EnvironmentVariableNotFound => {},
++            error.OutOfMemory => |e| return e,
+         }
+
+-        if (native_target.os.tag != .windows) {
+-            const triple = try native_target.linuxTriple(allocator);
+-            const qual = native_target.cpu.arch.ptrBitWidth();
+-
+-            // TODO: $ ld --verbose | grep SEARCH_DIR
+-            // the output contains some paths that end with lib64, maybe include them too?
+-            // TODO: what is the best possible order of things?
+-            // TODO: some of these are suspect and should only be added on some systems. audit needed.
+-
+-            try self.addIncludeDir("/usr/local/include");
+-            try self.addLibDirFmt("/usr/local/lib{d}", .{qual});
+-            try self.addLibDir("/usr/local/lib");
+-
+-            try self.addIncludeDirFmt("/usr/include/{s}", .{triple});
+-            try self.addLibDirFmt("/usr/lib/{s}", .{triple});
+-
+-            try self.addIncludeDir("/usr/include");
+-            try self.addLibDirFmt("/lib{d}", .{qual});
+-            try self.addLibDir("/lib");
+-            try self.addLibDirFmt("/usr/lib{d}", .{qual});
+-            try self.addLibDir("/usr/lib");
+-
+-            // example: on a 64-bit debian-based linux distro, with zlib installed from apt:
+-            // zlib.h is in /usr/include (added above)
+-            // libz.so.1 is in /lib/x86_64-linux-gnu (added here)
+-            try self.addLibDirFmt("/lib/{s}", .{triple});
++        if (process.getEnvVarOwned(allocator, "DYLD_FRAMEWORK_PATH")) |dyld_framework_path| {
++            defer allocator.free(dyld_framework_path);
++            var it = mem.tokenize(dyld_framework_path, ":");
++            while (true) {
++                const dir = it.next() orelse break;
++                try self.addFrameworkDir(dir);
++            }
++        } else |err| switch (err) {
++            error.InvalidUtf8 => {},
++            error.EnvironmentVariableNotFound => {},
++            error.OutOfMemory => |e| return e,
+         }
+
+         return self;