zig build: add --pkg-config option

Useful to override path to pkg-config executable, for example when
it's name is prepended by target triple for cross-compilation purposes.

Signed-off-by: Eric Joldasov <[email protected]>

Author: BratishkaErik

lib/compiler/build_runner.zig

@@ -187,6 +187,9 @@ pub fn main() !void {
                 };
             } else if (mem.eql(u8, arg, "--zig-lib-dir")) {
                 builder.zig_lib_dir = .{ .cwd_relative = nextArgOrFatal(args, &arg_idx) };
+            } else if (mem.eql(u8, arg, "--pkg-config-exe")) {
+                const next_arg = nextArgOrFatal(args, &arg_idx);
+                builder.graph.pkg_config_exe = next_arg;
             } else if (mem.eql(u8, arg, "--seed")) {
                 const next_arg = nextArg(args, &arg_idx) orelse
                     fatalWithHint("expected u32 after '{s}'", .{arg});
@@ -1186,6 +1189,7 @@ fn usage(b: *std.Build, out_stream: anytype) !void {
         \\  --global-cache-dir [path]    Override path to global Zig cache directory
         \\  --zig-lib-dir [arg]          Override path to Zig lib directory
         \\  --build-runner [file]        Override path to build runner
+        \\  --pkg-config-exe [file]      Override path to pkg-config executable (default: pkg-config)
         \\  --seed [integer]             For shuffling dependency traversal order (default: random)
         \\  --debug-log [scope]          Enable debugging the compiler
         \\  --debug-pkg-config           Fail if unknown pkg-config flags encountered

lib/std/Build.zig

@@ -115,6 +115,7 @@ pub const Graph = struct {
     system_package_mode: bool = false,
     cache: Cache,
     zig_exe: [:0]const u8,
+    pkg_config_exe: [:0]const u8 = "pkg-config",
     env_map: EnvMap,
     global_cache_root: Cache.Directory,
     needed_lazy_dependencies: std.StringArrayHashMapUnmanaged(void) = .{},

lib/std/Build/Step/Compile.zig

@@ -700,7 +700,7 @@ fn runPkgConfig(compile: *Compile, lib_name: []const u8) !PkgConfigResult {
 
     var code: u8 = undefined;
     const stdout = if (b.runAllowFail(&[_][]const u8{
-        "pkg-config",
+        b.graph.pkg_config_exe,
         pkg_name,
         "--cflags",
         "--libs",
@@ -1817,7 +1817,7 @@ pub fn doAtomicSymLinks(
 }
 
 fn execPkgConfigList(compile: *std.Build, out_code: *u8) (PkgConfigError || RunError)![]const PkgConfigPkg {
-    const stdout = try compile.runAllowFail(&[_][]const u8{ "pkg-config", "--list-all" }, out_code, .Ignore);
+    const stdout = try compile.runAllowFail(&[_][]const u8{ compile.graph.pkg_config_exe, "--list-all" }, out_code, .Ignore);
     var list = ArrayList(PkgConfigPkg).init(compile.allocator);
     errdefer list.deinit();
     var line_it = mem.tokenizeAny(u8, stdout, "\r\n");