Revert "Revert "Merge pull request #10950 from hexops/sg/responsefiles""

This reverts commit 5ab5e2e6731a9f1198df6c53134545ccc6a6bbd3.

2 files changed, 202 insertions, 144 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index 07e9055b1d..5dcd0e513f 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -17,6 +17,7 @@ const fmt_lib = std.fmt;
 const File = std.fs.File;
 const CrossTarget = std.zig.CrossTarget;
 const NativeTargetInfo = std.zig.system.NativeTargetInfo;
+const Sha256 = std.crypto.hash.sha2.Sha256;
 
 pub const FmtStep = @import("build/FmtStep.zig");
 pub const TranslateCStep = @import("build/TranslateCStep.zig");
@@ -2892,6 +2893,41 @@ pub const LibExeObjStep = struct {
 
         try zig_args.append("--enable-cache");
 
+        // Windows has an argument length limit of 32,766 characters, macOS 262,144 and Linux
+        // 2,097,152. If our args exceed 30 KiB, we instead write them to a "response file" and
+        // pass that to zig, e.g. via 'zig build-lib @args.rsp'
+        var args_length: usize = 0;
+        for (zig_args.items) |arg| {
+            args_length += arg.len + 1; // +1 to account for null terminator
+        }
+        if (args_length >= 30 * 1024) {
+            const args_dir = try fs.path.join(
+                builder.allocator,
+                &[_][]const u8{ builder.pathFromRoot("zig-cache"), "args" },
+            );
+            try std.fs.cwd().makePath(args_dir);
+
+            // Write the args to zig-cache/args/<SHA256 hash of args> to avoid conflicts with
+            // other zig build commands running in parallel.
+            const partially_quoted = try std.mem.join(builder.allocator, "\" \"", zig_args.items[2..]);
+            const args = try std.mem.concat(builder.allocator, u8, &[_][]const u8{ "\"", partially_quoted, "\"" });
+
+            var args_hash: [Sha256.digest_length]u8 = undefined;
+            Sha256.hash(args, &args_hash, .{});
+            var args_hex_hash: [Sha256.digest_length * 2]u8 = undefined;
+            _ = try std.fmt.bufPrint(
+                &args_hex_hash,
+                "{s}",
+                .{std.fmt.fmtSliceHexLower(&args_hash)},
+            );
+
+            const args_file = try fs.path.join(builder.allocator, &[_][]const u8{ args_dir, args_hex_hash[0..] });
+            try std.fs.cwd().writeFile(args_file, args);
+
+            zig_args.shrinkRetainingCapacity(2);
+            try zig_args.append(try std.mem.concat(builder.allocator, u8, &[_][]const u8{ "@", args_file }));
+        }
+
         const output_dir_nl = try builder.execFromStep(zig_args.items, &self.step);
         const build_output_dir = mem.trimRight(u8, output_dir_nl, "\r\n");
 
diff --git a/src/main.zig b/src/main.zig
index ebbbe6da25..958849f0a5 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -767,11 +767,33 @@ fn buildOutputType(
             }
 
             soname = .yes_default_value;
-            const args = all_args[2..];
-            var i: usize = 0;
-            args_loop: while (i < args.len) : (i += 1) {
-                const arg = args[i];
-                if (mem.startsWith(u8, arg, "-")) {
+
+            const Iterator = struct {
+                resp_file: ?ArgIteratorResponseFile = null,
+                args: []const []const u8,
+                i: usize = 0,
+                fn next(it: *@This()) ?[]const u8 {
+                    if (it.i >= it.args.len) {
+                        if (it.resp_file) |*resp| return if (resp.next()) |sentinel| std.mem.span(sentinel) else null;
+                        return null;
+                    }
+                    defer it.i += 1;
+                    return it.args[it.i];
+                }
+            };
+            var args_iter = Iterator{
+                .args = all_args[2..],
+            };
+
+            args_loop: while (args_iter.next()) |arg| {
+                if (mem.startsWith(u8, arg, "@")) {
+                    // This is a "compiler response file". We must parse the file and treat its
+                    // contents as command line parameters.
+                    const resp_file_path = arg[1..];
+                    args_iter.resp_file = initArgIteratorResponseFile(arena, resp_file_path) catch |err| {
+                        fatal("unable to read response file '{s}': {s}", .{ resp_file_path, @errorName(err) });
+                    };
+                } else if (mem.startsWith(u8, arg, "-")) {
                     if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                         try io.getStdOut().writeAll(usage_build_generic);
                         return cleanExit();
@@ -779,73 +801,71 @@ fn buildOutputType(
                         if (arg_mode == .run) {
                             // The index refers to all_args so skip `zig` `run`
                             // and `--`
-                            runtime_args_start = i + 3;
+                            runtime_args_start = args_iter.i + 3;
                             break :args_loop;
                         } else {
                             fatal("unexpected end-of-parameter mark: --", .{});
                         }
                     } else if (mem.eql(u8, arg, "--pkg-begin")) {
-                        if (i + 2 >= args.len) fatal("Expected 2 arguments after {s}", .{arg});
-                        i += 1;
-                        const pkg_name = args[i];
-                        i += 1;
-                        const pkg_path = args[i];
+                        const pkg_name = args_iter.next();
+                        const pkg_path = args_iter.next();
+                        if (pkg_name == null or pkg_path == null) fatal("Expected 2 arguments after {s}", .{arg});
 
                         const new_cur_pkg = Package.create(
                             gpa,
-                            fs.path.dirname(pkg_path),
-                            fs.path.basename(pkg_path),
+                            fs.path.dirname(pkg_path.?),
+                            fs.path.basename(pkg_path.?),
                         ) catch |err| {
-                            fatal("Failed to add package at path {s}: {s}", .{ pkg_path, @errorName(err) });
+                            fatal("Failed to add package at path {s}: {s}", .{ pkg_path.?, @errorName(err) });
                         };
-                        try cur_pkg.addAndAdopt(gpa, pkg_name, new_cur_pkg);
+                        try cur_pkg.addAndAdopt(gpa, pkg_name.?, new_cur_pkg);
                         cur_pkg = new_cur_pkg;
                     } else if (mem.eql(u8, arg, "--pkg-end")) {
                         cur_pkg = cur_pkg.parent orelse
                             fatal("encountered --pkg-end with no matching --pkg-begin", .{});
                     } else if (mem.eql(u8, arg, "--main-pkg-path")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        main_pkg_path = args[i];
+                        main_pkg_path = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "-cflags")) {
                         extra_cflags.shrinkRetainingCapacity(0);
                         while (true) {
-                            i += 1;
-                            if (i >= args.len) fatal("expected -- after -cflags", .{});
-                            if (mem.eql(u8, args[i], "--")) break;
-                            try extra_cflags.append(args[i]);
+                            const next_arg = args_iter.next() orelse {
+                                fatal("expected -- after -cflags", .{});
+                            };
+                            if (mem.eql(u8, next_arg, "--")) break;
+                            try extra_cflags.append(next_arg);
                         }
                     } else if (mem.eql(u8, arg, "--color")) {
-                        if (i + 1 >= args.len) {
+                        const next_arg = args_iter.next() orelse {
                             fatal("expected [auto|on|off] after --color", .{});
-                        }
-                        i += 1;
-                        const next_arg = args[i];
+                        };
                         color = std.meta.stringToEnum(Color, next_arg) orelse {
                             fatal("expected [auto|on|off] after --color, found '{s}'", .{next_arg});
                         };
                     } else if (mem.eql(u8, arg, "--subsystem")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        if (mem.eql(u8, args[i], "console")) {
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
+                        if (mem.eql(u8, next_arg, "console")) {
                             subsystem = .Console;
-                        } else if (mem.eql(u8, args[i], "windows")) {
+                        } else if (mem.eql(u8, next_arg, "windows")) {
                             subsystem = .Windows;
-                        } else if (mem.eql(u8, args[i], "posix")) {
+                        } else if (mem.eql(u8, next_arg, "posix")) {
                             subsystem = .Posix;
-                        } else if (mem.eql(u8, args[i], "native")) {
+                        } else if (mem.eql(u8, next_arg, "native")) {
                             subsystem = .Native;
-                        } else if (mem.eql(u8, args[i], "efi_application")) {
+                        } else if (mem.eql(u8, next_arg, "efi_application")) {
                             subsystem = .EfiApplication;
-                        } else if (mem.eql(u8, args[i], "efi_boot_service_driver")) {
+                        } else if (mem.eql(u8, next_arg, "efi_boot_service_driver")) {
                             subsystem = .EfiBootServiceDriver;
-                        } else if (mem.eql(u8, args[i], "efi_rom")) {
+                        } else if (mem.eql(u8, next_arg, "efi_rom")) {
                             subsystem = .EfiRom;
-                        } else if (mem.eql(u8, args[i], "efi_runtime_driver")) {
+                        } else if (mem.eql(u8, next_arg, "efi_runtime_driver")) {
                             subsystem = .EfiRuntimeDriver;
                         } else {
                             fatal("invalid: --subsystem: '{s}'. Options are:\n{s}", .{
-                                args[i],
+                                next_arg,
                                 \\  console
                                 \\  windows
                                 \\  posix
@@ -858,67 +878,71 @@ fn buildOutputType(
                             });
                         }
                     } else if (mem.eql(u8, arg, "-O")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        optimize_mode_string = args[i];
+                        optimize_mode_string = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--entry")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        entry = args[i];
+                        entry = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--stack")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        stack_size_override = std.fmt.parseUnsigned(u64, args[i], 0) catch |err| {
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
+                        stack_size_override = std.fmt.parseUnsigned(u64, next_arg, 0) catch |err| {
                             fatal("unable to parse '{s}': {s}", .{ arg, @errorName(err) });
                         };
                     } else if (mem.eql(u8, arg, "--image-base")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        image_base_override = std.fmt.parseUnsigned(u64, args[i], 0) catch |err| {
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
+                        image_base_override = std.fmt.parseUnsigned(u64, next_arg, 0) catch |err| {
                             fatal("unable to parse '{s}': {s}", .{ arg, @errorName(err) });
                         };
                     } else if (mem.eql(u8, arg, "--name")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        provided_name = args[i];
+                        provided_name = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "-rpath")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try rpath_list.append(args[i]);
+                        try rpath_list.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "--library-directory") or mem.eql(u8, arg, "-L")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try lib_dirs.append(args[i]);
+                        try lib_dirs.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "-F")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try framework_dirs.append(args[i]);
+                        try framework_dirs.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "-framework")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try frameworks.append(args[i]);
+                        try frameworks.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "-install_name")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        install_name = args[i];
+                        install_name = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "-T") or mem.eql(u8, arg, "--script")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        linker_script = args[i];
+                        linker_script = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--version-script")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        version_script = args[i];
+                        version_script = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--library") or mem.eql(u8, arg, "-l")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                         // We don't know whether this library is part of libc or libc++ until
                         // we resolve the target, so we simply append to the list for now.
-                        i += 1;
-                        try system_libs.put(args[i], .{ .needed = false });
+                        try system_libs.put(next_arg, .{ .needed = false });
                     } else if (mem.eql(u8, arg, "--needed-library") or mem.eql(u8, arg, "-needed-l")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try system_libs.put(args[i], .{ .needed = true });
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
+                        try system_libs.put(next_arg, .{ .needed = true });
                     } else if (mem.eql(u8, arg, "-D") or
                         mem.eql(u8, arg, "-isystem") or
                         mem.eql(u8, arg, "-I") or
@@ -927,31 +951,30 @@ fn buildOutputType(
                         mem.eql(u8, arg, "-iframework") or
                         mem.eql(u8, arg, "-iframeworkwithsysroot"))
                     {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
                         try clang_argv.append(arg);
-                        try clang_argv.append(args[i]);
+                        try clang_argv.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "--version")) {
-                        if (i + 1 >= args.len) {
-                            fatal("expected parameter after --version", .{});
-                        }
-                        i += 1;
-                        version = std.builtin.Version.parse(args[i]) catch |err| {
-                            fatal("unable to parse --version '{s}': {s}", .{ args[i], @errorName(err) });
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
+                        version = std.builtin.Version.parse(next_arg) catch |err| {
+                            fatal("unable to parse --version '{s}': {s}", .{ next_arg, @errorName(err) });
                         };
                         have_version = true;
                     } else if (mem.eql(u8, arg, "-target")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        target_arch_os_abi = args[i];
+                        target_arch_os_abi = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "-mcpu")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        target_mcpu = args[i];
+                        target_mcpu = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "-mcmodel")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        machine_code_model = parseCodeModel(args[i]);
+                        machine_code_model = parseCodeModel(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.startsWith(u8, arg, "-ofmt=")) {
                         target_ofmt = arg["-ofmt=".len..];
                     } else if (mem.startsWith(u8, arg, "-mcpu=")) {
@@ -961,50 +984,51 @@ fn buildOutputType(
                     } else if (mem.startsWith(u8, arg, "-O")) {
                         optimize_mode_string = arg["-O".len..];
                     } else if (mem.eql(u8, arg, "--dynamic-linker")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        target_dynamic_linker = args[i];
+                        target_dynamic_linker = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--sysroot")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        sysroot = args[i];
+                        sysroot = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                         try clang_argv.append("-isysroot");
-                        try clang_argv.append(args[i]);
+                        try clang_argv.append(sysroot.?);
                     } else if (mem.eql(u8, arg, "--libc")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        libc_paths_file = args[i];
+                        libc_paths_file = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--test-filter")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        test_filter = args[i];
+                        test_filter = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--test-name-prefix")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        test_name_prefix = args[i];
+                        test_name_prefix = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--test-cmd")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        try test_exec_args.append(args[i]);
+                        try test_exec_args.append(args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        });
                     } else if (mem.eql(u8, arg, "--cache-dir")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        override_local_cache_dir = args[i];
+                        override_local_cache_dir = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--global-cache-dir")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        override_global_cache_dir = args[i];
+                        override_global_cache_dir = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--zig-lib-dir")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
-                        override_lib_dir = args[i];
+                        override_lib_dir = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                     } else if (mem.eql(u8, arg, "--debug-log")) {
-                        if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
-                        i += 1;
+                        const next_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                         if (!build_options.enable_logging) {
                             std.log.warn("Zig was compiled without logging enabled (-Dlog). --debug-log has no effect.", .{});
                         } else {
-                            try log_scopes.append(gpa, args[i]);
+                            try log_scopes.append(gpa, next_arg);
                         }
                     } else if (mem.eql(u8, arg, "--debug-link-snapshot")) {
                         if (!build_options.enable_link_snapshots) {
@@ -1177,11 +1201,9 @@ fn buildOutputType(
                     } else if (mem.eql(u8, arg, "-fno-allow-shlib-undefined")) {
                         linker_allow_shlib_undefined = false;
                     } else if (mem.eql(u8, arg, "-z")) {
-                        i += 1;
-                        if (i >= args.len) {
-                            fatal("expected linker extension flag after '{s}'", .{arg});
-                        }
-                        const z_arg = args[i];
+                        const z_arg = args_iter.next() orelse {
+                            fatal("expected parameter after {s}", .{arg});
+                        };
                         if (mem.eql(u8, z_arg, "nodelete")) {
                             linker_z_nodelete = true;
                         } else if (mem.eql(u8, z_arg, "notext")) {
@@ -4300,6 +4322,17 @@ pub fn lldMain(
     return @bitCast(u8, @truncate(i8, exit_code));
 }
 
+const ArgIteratorResponseFile = process.ArgIteratorGeneral(.{ .comments = true, .single_quotes = true });
+
+/// Initialize the arguments from a Response File. "*.rsp"
+fn initArgIteratorResponseFile(allocator: Allocator, resp_file_path: []const u8) !ArgIteratorResponseFile {
+    const max_bytes = 10 * 1024 * 1024; // 10 MiB of command line arguments is a reasonable limit
+    var cmd_line = try fs.cwd().readFileAlloc(allocator, resp_file_path, max_bytes);
+    errdefer allocator.free(cmd_line);
+
+    return ArgIteratorResponseFile.initTakeOwnership(allocator, cmd_line);
+}
+
 const clang_args = @import("clang_options.zig").list;
 
 pub const ClangArgIterator = struct {
@@ -4391,17 +4424,6 @@ pub const ClangArgIterator = struct {
         };
     }
 
-    const ArgIteratorResponseFile = process.ArgIteratorGeneral(.{ .comments = true, .single_quotes = true });
-
-    /// Initialize the arguments from a Response File. "*.rsp"
-    fn initArgIteratorResponseFile(allocator: Allocator, resp_file_path: []const u8) !ArgIteratorResponseFile {
-        const max_bytes = 10 * 1024 * 1024; // 10 MiB of command line arguments is a reasonable limit
-        var cmd_line = try fs.cwd().readFileAlloc(allocator, resp_file_path, max_bytes);
-        errdefer allocator.free(cmd_line);
-
-        return ArgIteratorResponseFile.initTakeOwnership(allocator, cmd_line);
-    }
-
     fn next(self: *ClangArgIterator) !void {
         assert(self.has_next);
         assert(self.next_index < self.argv.len);