init: replace '--strip' with '--minimal'

This option never worked properly (it emitted wrongly-formatted code),
and it doesn't seem particularly *useful* -- someone who's proficient
enough with `std.Build` to not need explanations probably just wants to
write their own thing. Meanwhile, the use case of writing your own
`build.zig` was extremely poorly served, because `build.zig.zon` *needs*
to be generated programmatically for a correct `fingerprint`, but the
only ways to do that were to a) do it wrong and get an error, or b) get
the full init template and delete the vast majority of it. Both of these
were pretty clunky, and `-s` didn't really help.

So, replace this flag with a new one, `--minimal`/`-m`, which uses a
different template. This template is trivial enough that I opted to just
hardcode it into the compiler for simplicity. The main job of
`zig init -m` is to generate a correct `build.zig.zon` (if it is unable
to do this, it exits with a fatal error). In addition, it will *attempt*
to generate a tiny stub `build.zig`, with only an `std` import and an
empty `pub fn build`. However, if `build.zig` already exists, it will
avoid overwriting it, and doesn't even complain. This serves the use
case of writing `build.zig` manually and *then* running `zig init -m`
to generate an appropriate `build.zig.zon`.

1 files changed, 92 insertions, 54 deletions

diff --git a/src/main.zig b/src/main.zig
index 144515b46e..a0a40ae093 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -4648,14 +4648,14 @@ const usage_init =
 fn cmdInit(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
     dev.check(.init_command);
 
-    var strip = false;
+    var template: enum { example, minimal } = .example;
     {
         var i: usize = 0;
         while (i < args.len) : (i += 1) {
             const arg = args[i];
             if (mem.startsWith(u8, arg, "-")) {
-                if (mem.eql(u8, arg, "-s") or mem.eql(u8, arg, "--strip")) {
-                    strip = true;
+                if (mem.eql(u8, arg, "-m") or mem.eql(u8, arg, "--minimal")) {
+                    template = .minimal;
                 } else if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try fs.File.stdout().writeAll(usage_init);
                     return cleanExit();
@@ -4668,40 +4668,79 @@ fn cmdInit(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
         }
     }
 
-    var templates = findTemplates(gpa, arena, strip);
-    defer templates.deinit();
-
     const cwd_path = try introspect.getResolvedCwd(arena);
     const cwd_basename = fs.path.basename(cwd_path);
     const sanitized_root_name = try sanitizeExampleName(arena, cwd_basename);
 
-    const s = fs.path.sep_str;
-    const template_paths = [_][]const u8{
-        Package.build_zig_basename,
-        Package.Manifest.basename,
-        "src" ++ s ++ "main.zig",
-        "src" ++ s ++ "root.zig",
-    };
-    var ok_count: usize = 0;
-
     const fingerprint: Package.Fingerprint = .generate(sanitized_root_name);
 
-    for (template_paths) |template_path| {
-        if (templates.write(arena, fs.cwd(), sanitized_root_name, template_path, fingerprint)) |_| {
-            std.log.info("created {s}", .{template_path});
-            ok_count += 1;
-        } else |err| switch (err) {
-            error.PathAlreadyExists => std.log.info("preserving already existing file: {s}", .{
-                template_path,
-            }),
-            else => std.log.err("unable to write {s}: {s}\n", .{ template_path, @errorName(err) }),
-        }
-    }
+    switch (template) {
+        .example => {
+            var templates = findTemplates(gpa, arena);
+            defer templates.deinit();
+
+            const s = fs.path.sep_str;
+            const template_paths = [_][]const u8{
+                Package.build_zig_basename,
+                Package.Manifest.basename,
+                "src" ++ s ++ "main.zig",
+                "src" ++ s ++ "root.zig",
+            };
+            var ok_count: usize = 0;
+
+            for (template_paths) |template_path| {
+                if (templates.write(arena, fs.cwd(), sanitized_root_name, template_path, fingerprint)) |_| {
+                    std.log.info("created {s}", .{template_path});
+                    ok_count += 1;
+                } else |err| switch (err) {
+                    error.PathAlreadyExists => std.log.info("preserving already existing file: {s}", .{
+                        template_path,
+                    }),
+                    else => std.log.err("unable to write {s}: {s}\n", .{ template_path, @errorName(err) }),
+                }
+            }
 
-    if (ok_count == template_paths.len) {
-        std.log.info("see `zig build --help` for a menu of options", .{});
+            if (ok_count == template_paths.len) {
+                std.log.info("see `zig build --help` for a menu of options", .{});
+            }
+            return cleanExit();
+        },
+        .minimal => {
+            writeSimpleTemplateFile(Package.Manifest.basename,
+                \\.{{
+                \\    .name = .{s},
+                \\    .version = "{s}",
+                \\    .paths = .{{""}},
+                \\    .fingerprint = 0x{x},
+                \\}}
+                \\
+            , .{
+                sanitized_root_name,
+                build_options.version,
+                fingerprint.int(),
+            }) catch |err| switch (err) {
+                else => fatal("failed to create '{s}': {s}", .{ Package.Manifest.basename, @errorName(err) }),
+                error.PathAlreadyExists => fatal("refusing to overwrite '{s}'", .{Package.Manifest.basename}),
+            };
+            writeSimpleTemplateFile(Package.build_zig_basename,
+                \\const std = @import("std");
+                \\pub fn build(b: *std.Build) void {{
+                \\    _ = b; // stub
+                \\}}
+                \\
+            , .{}) catch |err| switch (err) {
+                else => fatal("failed to create '{s}': {s}", .{ Package.build_zig_basename, @errorName(err) }),
+                // `build.zig` already existing is okay: the user has just used `zig init` to set up
+                // their `build.zig.zon` *after* writing their `build.zig`. So this one isn't fatal.
+                error.PathAlreadyExists => {
+                    std.log.info("successfully populated '{s}', preserving existing '{s}'", .{ Package.Manifest.basename, Package.build_zig_basename });
+                    return cleanExit();
+                },
+            };
+            std.log.info("successfully populated '{s}' and '{s}'", .{ Package.Manifest.basename, Package.build_zig_basename });
+            return cleanExit();
+        },
     }
-    return cleanExit();
 }
 
 fn sanitizeExampleName(arena: Allocator, bytes: []const u8) error{OutOfMemory}![]const u8 {
@@ -7229,13 +7268,20 @@ fn loadManifest(
             0,
         ) catch |err| switch (err) {
             error.FileNotFound => {
-                const fingerprint: Package.Fingerprint = .generate(options.root_name);
-                var templates = findTemplates(gpa, arena, true);
-                defer templates.deinit();
-                templates.write(arena, options.dir, options.root_name, Package.Manifest.basename, fingerprint) catch |e| {
-                    fatal("unable to write {s}: {s}", .{
-                        Package.Manifest.basename, @errorName(e),
-                    });
+                writeSimpleTemplateFile(Package.Manifest.basename,
+                    \\.{{
+                    \\    .name = .{s},
+                    \\    .version = "{s}",
+                    \\    .paths = .{{""}},
+                    \\    .fingerprint = 0x{x},
+                    \\}}
+                    \\
+                , .{
+                    options.root_name,
+                    build_options.version,
+                    Package.Fingerprint.generate(options.root_name).int(),
+                }) catch |e| {
+                    fatal("unable to write {s}: {s}", .{ Package.Manifest.basename, @errorName(e) });
                 };
                 continue;
             },
@@ -7276,7 +7322,6 @@ const Templates = struct {
     zig_lib_directory: Cache.Directory,
     dir: fs.Dir,
     buffer: std.ArrayList(u8),
-    strip: bool,
 
     fn deinit(templates: *Templates) void {
         templates.zig_lib_directory.handle.close();
@@ -7305,23 +7350,9 @@ const Templates = struct {
         };
         templates.buffer.clearRetainingCapacity();
         try templates.buffer.ensureUnusedCapacity(contents.len);
-        var new_line = templates.strip;
         var i: usize = 0;
         while (i < contents.len) {
-            if (new_line) {
-                const trimmed = std.mem.trimLeft(u8, contents[i..], " ");
-                if (std.mem.startsWith(u8, trimmed, "//")) {
-                    i += std.mem.indexOfScalar(u8, contents[i..], '\n') orelse break;
-                    i += 1;
-                    continue;
-                } else {
-                    new_line = false;
-                }
-            }
-
-            if (templates.strip and contents[i] == '\n') {
-                new_line = true;
-            } else if (contents[i] == '_' or contents[i] == '.') {
+            if (contents[i] == '_' or contents[i] == '.') {
                 // Both '_' and '.' are allowed because depending on the context
                 // one prefix will be valid, while the other might not.
                 if (std.mem.startsWith(u8, contents[i + 1 ..], "NAME")) {
@@ -7350,8 +7381,16 @@ const Templates = struct {
         });
     }
 };
+fn writeSimpleTemplateFile(file_name: []const u8, comptime fmt: []const u8, args: anytype) !void {
+    const f = try fs.cwd().createFile(file_name, .{ .exclusive = true });
+    defer f.close();
+    var buf: [4096]u8 = undefined;
+    var fw = f.writer(&buf);
+    try fw.interface.print(fmt, args);
+    try fw.interface.flush();
+}
 
-fn findTemplates(gpa: Allocator, arena: Allocator, strip: bool) Templates {
+fn findTemplates(gpa: Allocator, arena: Allocator) Templates {
     const cwd_path = introspect.getResolvedCwd(arena) catch |err| {
         fatal("unable to get cwd: {s}", .{@errorName(err)});
     };
@@ -7375,7 +7414,6 @@ fn findTemplates(gpa: Allocator, arena: Allocator, strip: bool) Templates {
         .zig_lib_directory = zig_lib_directory,
         .dir = template_dir,
         .buffer = std.ArrayList(u8).init(gpa),
-        .strip = strip,
     };
 }