get zig fetch working with the new system

* start renaming "package" to "module" (see #14307)
  - build system gains `main_mod_path` and `main_pkg_path` is still
    there but it is deprecated.
* eliminate the object-oriented memory management style of what was
  previously `*Package`. Now it is `*Package.Module` and all pointers
  point to externally managed memory.
* fixes to get the new Fetch.zig code working. The previous commit was
  work-in-progress. There are still two commented out code paths, the
  one that leads to `Compilation.create` and the one for `zig build`
  that fetches the entire dependency tree and creates the required
  modules for the build runner.

Author: andrewrk

build.zig

@@ -88,7 +88,7 @@ pub fn build(b: *std.Build) !void {
         .name = "check-case",
         .root_source_file = .{ .path = "test/src/Cases.zig" },
         .optimize = optimize,
-        .main_pkg_path = .{ .path = "." },
+        .main_mod_path = .{ .path = "." },
     });
     check_case_exe.stack_size = stack_size;
     check_case_exe.single_threaded = single_threaded;

lib/std/Build.zig

@@ -634,6 +634,9 @@ pub const ExecutableOptions = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// Deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -652,7 +655,7 @@ pub fn addExecutable(b: *Build, options: ExecutableOptions) *Step.Compile {
         .use_llvm = options.use_llvm,
         .use_lld = options.use_lld,
         .zig_lib_dir = options.zig_lib_dir orelse b.zig_lib_dir,
-        .main_pkg_path = options.main_pkg_path,
+        .main_mod_path = options.main_mod_path orelse options.main_pkg_path,
     });
 }
 
@@ -667,6 +670,9 @@ pub const ObjectOptions = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// Deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -683,7 +689,7 @@ pub fn addObject(b: *Build, options: ObjectOptions) *Step.Compile {
         .use_llvm = options.use_llvm,
         .use_lld = options.use_lld,
         .zig_lib_dir = options.zig_lib_dir orelse b.zig_lib_dir,
-        .main_pkg_path = options.main_pkg_path,
+        .main_mod_path = options.main_mod_path orelse options.main_pkg_path,
     });
 }
 
@@ -699,6 +705,9 @@ pub const SharedLibraryOptions = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// Deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -717,7 +726,7 @@ pub fn addSharedLibrary(b: *Build, options: SharedLibraryOptions) *Step.Compile
         .use_llvm = options.use_llvm,
         .use_lld = options.use_lld,
         .zig_lib_dir = options.zig_lib_dir orelse b.zig_lib_dir,
-        .main_pkg_path = options.main_pkg_path,
+        .main_mod_path = options.main_mod_path orelse options.main_pkg_path,
     });
 }
 
@@ -733,6 +742,9 @@ pub const StaticLibraryOptions = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// Deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -751,7 +763,7 @@ pub fn addStaticLibrary(b: *Build, options: StaticLibraryOptions) *Step.Compile
         .use_llvm = options.use_llvm,
         .use_lld = options.use_lld,
         .zig_lib_dir = options.zig_lib_dir orelse b.zig_lib_dir,
-        .main_pkg_path = options.main_pkg_path,
+        .main_mod_path = options.main_mod_path orelse options.main_pkg_path,
     });
 }
 
@@ -769,6 +781,9 @@ pub const TestOptions = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// Deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -787,7 +802,7 @@ pub fn addTest(b: *Build, options: TestOptions) *Step.Compile {
         .use_llvm = options.use_llvm,
         .use_lld = options.use_lld,
         .zig_lib_dir = options.zig_lib_dir orelse b.zig_lib_dir,
-        .main_pkg_path = options.main_pkg_path,
+        .main_mod_path = options.main_mod_path orelse options.main_pkg_path,
     });
 }
 

lib/std/Build/Cache.zig

@@ -9,6 +9,13 @@ pub const Directory = struct {
     path: ?[]const u8,
     handle: fs.Dir,
 
+    pub fn cwd() Directory {
+        return .{
+            .path = null,
+            .handle = fs.cwd(),
+        };
+    }
+
     pub fn join(self: Directory, allocator: Allocator, paths: []const []const u8) ![]u8 {
         if (self.path) |p| {
             // TODO clean way to do this with only 1 allocation
@@ -53,6 +60,10 @@ pub const Directory = struct {
             try writer.writeAll(fs.path.sep_str);
         }
     }
+
+    pub fn eql(self: Directory, other: Directory) bool {
+        return self.handle.fd == other.handle.fd;
+    }
 };
 
 gpa: Allocator,

lib/std/Build/Step/Compile.zig

@@ -68,7 +68,7 @@ c_std: std.Build.CStd,
 /// Set via options; intended to be read-only after that.
 zig_lib_dir: ?LazyPath,
 /// Set via options; intended to be read-only after that.
-main_pkg_path: ?LazyPath,
+main_mod_path: ?LazyPath,
 exec_cmd_args: ?[]const ?[]const u8,
 filter: ?[]const u8,
 test_evented_io: bool = false,
@@ -316,6 +316,9 @@ pub const Options = struct {
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     zig_lib_dir: ?LazyPath = null,
+    main_mod_path: ?LazyPath = null,
+
+    /// deprecated; use `main_mod_path`.
     main_pkg_path: ?LazyPath = null,
 };
 
@@ -480,7 +483,7 @@ pub fn create(owner: *std.Build, options: Options) *Compile {
         .installed_headers = ArrayList(*Step).init(owner.allocator),
         .c_std = std.Build.CStd.C99,
         .zig_lib_dir = null,
-        .main_pkg_path = null,
+        .main_mod_path = null,
         .exec_cmd_args = null,
         .filter = options.filter,
         .test_runner = options.test_runner,
@@ -515,8 +518,8 @@ pub fn create(owner: *std.Build, options: Options) *Compile {
         lp.addStepDependencies(&self.step);
     }
 
-    if (options.main_pkg_path) |lp| {
-        self.main_pkg_path = lp.dupe(self.step.owner);
+    if (options.main_mod_path orelse options.main_pkg_path) |lp| {
+        self.main_mod_path = lp.dupe(self.step.owner);
         lp.addStepDependencies(&self.step);
     }
 
@@ -1998,8 +2001,8 @@ fn make(step: *Step, prog_node: *std.Progress.Node) !void {
         try zig_args.append(dir.getPath(b));
     }
 
-    if (self.main_pkg_path) |dir| {
-        try zig_args.append("--main-pkg-path");
+    if (self.main_mod_path) |dir| {
+        try zig_args.append("--main-mod-path");
         try zig_args.append(dir.getPath(b));
     }