zig build: add -l, --list-steps option to build_runner.zig

1 files changed, 22 insertions, 8 deletions

diff --git a/lib/build_runner.zig b/lib/build_runner.zig
index f2b2eba950..aeefb57bfc 100644
--- a/lib/build_runner.zig
+++ b/lib/build_runner.zig
@@ -93,6 +93,8 @@ pub fn main() !void {
                     std.debug.print("Expected argument after {s}\n\n", .{arg});
                     return usageAndErr(builder, false, stderr_stream);
                 };
+            } else if (mem.eql(u8, arg, "-l") or mem.eql(u8, arg, "--list-steps")) {
+                return steps(builder, false, stdout_stream);
             } else if (mem.eql(u8, arg, "--prefix-lib-dir")) {
                 dir_list.lib_dir = nextArg(args, &arg_idx) orelse {
                     std.debug.print("Expected argument after {s}\n\n", .{arg});
@@ -232,20 +234,13 @@ pub fn main() !void {
     };
 }
 
-fn usage(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !void {
+fn steps(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !void {
     // run the build script to collect the options
     if (!already_ran_build) {
         builder.resolveInstallPrefix(null, .{});
         try builder.runBuild(root);
     }
 
-    try out_stream.print(
-        \\Usage: {s} build [steps] [options]
-        \\
-        \\Steps:
-        \\
-    , .{builder.zig_exe});
-
     const allocator = builder.allocator;
     for (builder.top_level_steps.items) |top_level_step| {
         const name = if (&top_level_step.step == builder.default_step)
@@ -254,6 +249,23 @@ fn usage(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !voi
             top_level_step.step.name;
         try out_stream.print("  {s:<28} {s}\n", .{ name, top_level_step.description });
     }
+}
+
+fn usage(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !void {
+    // run the build script to collect the options
+    if (!already_ran_build) {
+        builder.resolveInstallPrefix(null, .{});
+        try builder.runBuild(root);
+    }
+
+    try out_stream.print(
+        \\
+        \\Usage: {s} build [steps] [options]
+        \\
+        \\Steps:
+        \\
+    , .{builder.zig_exe});
+    try steps(builder, true, out_stream);
 
     try out_stream.writeAll(
         \\
@@ -284,6 +296,7 @@ fn usage(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !voi
         \\                               Windows programs on Linux hosts. (default: no)
         \\
         \\  -h, --help                   Print this help and exit
+        \\  -l, --list-steps             Print available steps
         \\  --verbose                    Print commands before executing them
         \\  --color [auto|off|on]        Enable or disable colored error messages
         \\  --prominent-compile-errors   Output compile errors formatted for a human to read
@@ -292,6 +305,7 @@ fn usage(builder: *std.Build, already_ran_build: bool, out_stream: anytype) !voi
         \\
     );
 
+    const allocator = builder.allocator;
     if (builder.available_options_list.items.len == 0) {
         try out_stream.print("  (none)\n", .{});
     } else {