From c88e6e8aeec1b9a7d6888f298fef7949770c288b Mon Sep 17 00:00:00 2001
From: Jeff Fowler <jeffowler@gmail.com>
Date: Wed, 7 Feb 2018 23:45:20 +0100
Subject: [PATCH] improve behavior of `zig build` (#754)

See #748
---
 src/main.cpp                 | 33 +++++++++++++++++++++++----------
 std/special/build_runner.zig |  1 +
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index e3ef62be07909c486f1f5d985d95ccf27d9a4656..3df16e62b8d98fea3a3c8832c1888a88186e3c3d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -339,6 +339,7 @@ int main(int argc, char **argv) {
         const char *zig_exe_path = arg0;
         const char *build_file = "build.zig";
         bool asked_for_help = false;
+        bool asked_to_init = false;
 
         init_all_targets();
 
@@ -350,6 +351,9 @@ int main(int argc, char **argv) {
             if (strcmp(argv[i], "--help") == 0) {
                 asked_for_help = true;
                 args.append(argv[i]);
+            } else if (strcmp(argv[i], "--init") == 0) {
+                asked_to_init = true;
+                args.append(argv[i]);
             } else if (i + 1 < argc && strcmp(argv[i], "--build-file") == 0) {
                 build_file = argv[i + 1];
                 i += 1;
@@ -414,6 +418,7 @@ int main(int argc, char **argv) {
                         "\n"
                         "General Options:\n"
                         "  --help                 Print this help and exit\n"
+                        "  --init                 Generate a build.zig template\n"
                         "  --build-file [file]    Override path to build.zig\n"
                         "  --cache-dir [path]     Override path to cache directory\n"
                         "  --verbose              Print commands before executing them\n"
@@ -426,7 +431,6 @@ int main(int argc, char **argv) {
                         "  --prefix [path]        Override default install prefix\n"
                         "\n"
                         "Project-specific options become available when the build file is found.\n"
-                        "Run this command with no options to generate a build.zig template.\n"
                         "\n"
                         "Advanced Options:\n"
                         "  --build-file [file]    Override path to build.zig\n"
@@ -439,17 +443,26 @@ int main(int argc, char **argv) {
                         "  --verbose-cimport      Enable compiler debug output for C imports\n"
                         "\n"
                 , zig_exe_path);
-                return 0;
-            }
-            Buf *build_template_path = buf_alloc();
-            os_path_join(special_dir, buf_create_from_str("build_file_template.zig"), build_template_path);
+                return EXIT_SUCCESS;
+            } else if (asked_to_init) {
+                Buf *build_template_path = buf_alloc();
+                os_path_join(special_dir, buf_create_from_str("build_file_template.zig"), build_template_path);
 
-            if ((err = os_copy_file(build_template_path, &build_file_abs))) {
-                fprintf(stderr, "Unable to write build.zig template: %s\n", err_str(err));
-            } else {
-                fprintf(stderr, "Wrote build.zig template\n");
+                if ((err = os_copy_file(build_template_path, &build_file_abs))) {
+                    fprintf(stderr, "Unable to write build.zig template: %s\n", err_str(err));
+                } else {
+                    fprintf(stderr, "Wrote build.zig template\n");
+                }
+                return EXIT_SUCCESS;
             }
-            return 1;
+
+            fprintf(stderr,
+                    "No 'build.zig' file found.\n"
+                    "Initialize a 'build.zig' template file with `zig build --init`,\n"
+                    "or build an executable directly with `zig build-exe $FILENAME.zig`.\n"
+                    "See: `zig build --help` or `zig help` for more options.\n"
+                   );
+            return EXIT_FAILURE;
         }
 
         PackageTableEntry *build_pkg = codegen_create_package(g, buf_ptr(&build_file_dirname),
diff --git a/std/special/build_runner.zig b/std/special/build_runner.zig
index e1648276aafc29e3c320005a169e58aad798012c..c06b28167c8a82067b9a06192f79e208750c8443 100644
--- a/std/special/build_runner.zig
+++ b/std/special/build_runner.zig
@@ -149,6 +149,7 @@ fn usage(builder: &Builder, already_ran_build: bool, out_stream: &io.OutStream)
         \\
         \\General Options:
         \\  --help                 Print this help and exit
+        \\  --init                 Generate a build.zig template
         \\  --verbose              Print commands before executing them
         \\  --prefix [path]        Override default install prefix
         \\  --search-prefix [path] Add a path to look for binaries, libraries, headers
-- 
2.54.0