build system: add --debug-log advanced option to build runner

2 files changed, 15 insertions, 0 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index 750cff2202..c018397ffa 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -68,6 +68,7 @@ pub const Builder = struct {
     vcpkg_root: VcpkgRoot,
     pkg_config_pkg_list: ?(PkgConfigError![]const PkgConfigPkg) = null,
     args: ?[][]const u8 = null,
+    debug_log_scopes: []const []const u8 = &.{},
 
     const PkgConfigError = error{
         PkgConfigCrashed,
@@ -2334,6 +2335,11 @@ pub const LibExeObjStep = struct {
             try zig_args.append(self.name_prefix);
         }
 
+        for (builder.debug_log_scopes) |log_scope| {
+            try zig_args.append("--debug-log");
+            try zig_args.append(log_scope);
+        }
+
         if (builder.verbose_tokenize) zig_args.append("--verbose-tokenize") catch unreachable;
         if (builder.verbose_ast) zig_args.append("--verbose-ast") catch unreachable;
         if (builder.verbose_cimport) zig_args.append("--verbose-cimport") catch unreachable;
diff --git a/lib/std/special/build_runner.zig b/lib/std/special/build_runner.zig
index 666abf247a..d314cb4fee 100644
--- a/lib/std/special/build_runner.zig
+++ b/lib/std/special/build_runner.zig
@@ -51,6 +51,7 @@ pub fn main() !void {
     defer builder.destroy();
 
     var targets = ArrayList([]const u8).init(allocator);
+    var debug_log_scopes = ArrayList([]const u8).init(allocator);
 
     const stderr_stream = io.getStdErr().writer();
     const stdout_stream = io.getStdOut().writer();
@@ -136,6 +137,12 @@ pub fn main() !void {
                     warn("Expected argument after --zig-lib-dir\n\n", .{});
                     return usageAndErr(builder, false, stderr_stream);
                 };
+            } else if (mem.eql(u8, arg, "--debug-log")) {
+                const next_arg = nextArg(args, &arg_idx) orelse {
+                    warn("Expected argument after {s}\n\n", .{arg});
+                    return usageAndErr(builder, false, stderr_stream);
+                };
+                try debug_log_scopes.append(next_arg);
             } else if (mem.eql(u8, arg, "--verbose-tokenize")) {
                 builder.verbose_tokenize = true;
             } else if (mem.eql(u8, arg, "--verbose-ast")) {
@@ -166,6 +173,7 @@ pub fn main() !void {
         }
     }
 
+    builder.debug_log_scopes = debug_log_scopes.items;
     builder.resolveInstallPrefix(install_prefix, dir_list);
     try runBuild(builder);
 
@@ -261,6 +269,7 @@ fn usage(builder: *Builder, already_ran_build: bool, out_stream: anytype) !void
         \\  --build-file [file]          Override path to build.zig
         \\  --cache-dir [path]           Override path to zig cache directory
         \\  --zig-lib-dir [arg]          Override path to Zig lib directory
+        \\  --debug-log [scope]          Enable debugging the compiler
         \\  --verbose-tokenize           Enable compiler debug output for tokenization
         \\  --verbose-ast                Enable compiler debug output for parsing into an AST
         \\  --verbose-link               Enable compiler debug output for linking