From 57cfe0778c41565223ddc2abf4508a4ad43f1923 Mon Sep 17 00:00:00 2001
From: Christofer Nolander <christofer@nolander.me>
Date: Mon, 18 Mar 2024 19:48:11 +0100
Subject: [PATCH] `zig fetch`: resolve branch/tag names to commit SHA

---
 src/Package/Fetch.zig | 10 +++++++++-
 src/main.zig          | 22 +++++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/Package/Fetch.zig b/src/Package/Fetch.zig
index 93a6868603..7a791cfc2f 100644
--- a/src/Package/Fetch.zig
+++ b/src/Package/Fetch.zig
@@ -44,6 +44,8 @@ omit_missing_hash_error: bool,
 /// which specifies inclusion rules. This is intended to be true for the first
 /// fetch task and false for the recursive dependencies.
 allow_missing_paths_field: bool,
+/// If true and URL points to a Git repository, will use the latest commit.
+use_latest_commit: bool,
 
 // Above this are fields provided as inputs to `run`.
 // Below this are fields populated by `run`.
@@ -59,6 +61,8 @@ actual_hash: Manifest.Digest,
 has_build_zig: bool,
 /// Indicates whether the task aborted due to an out-of-memory condition.
 oom_flag: bool,
+/// If `use_latest_commit` was true, this will be the commit that was used.
+latest_commit: ?git.Oid,
 
 // This field is used by the CLI only, untouched by this file.
 
@@ -687,6 +691,7 @@ fn queueJobsForDeps(f: *Fetch) RunError!void {
                 .job_queue = f.job_queue,
                 .omit_missing_hash_error = false,
                 .allow_missing_paths_field = true,
+                .use_latest_commit = false,
 
                 .package_root = undefined,
                 .error_bundle = undefined,
@@ -695,6 +700,7 @@ fn queueJobsForDeps(f: *Fetch) RunError!void {
                 .actual_hash = undefined,
                 .has_build_zig = false,
                 .oom_flag = false,
+                .latest_commit = undefined,
 
                 .module = null,
             };
@@ -987,7 +993,9 @@ fn initResource(f: *Fetch, uri: std.Uri, server_header_buffer: []u8) RunError!Re
             }
             return f.fail(f.location_tok, try eb.printString("ref not found: {s}", .{want_ref}));
         };
-        if (uri.fragment == null) {
+        if (f.use_latest_commit) {
+            f.latest_commit = want_oid;
+        } else if (uri.fragment == null) {
             const notes_len = 1;
             try eb.addRootErrorMessage(.{
                 .msg = try eb.addString("url field is missing an explicit ref"),
diff --git a/src/main.zig b/src/main.zig
index db76f7605c..771e2527e3 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -5098,6 +5098,7 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
                     .job_queue = &job_queue,
                     .omit_missing_hash_error = true,
                     .allow_missing_paths_field = false,
+                    .use_latest_commit = false,
 
                     .package_root = undefined,
                     .error_bundle = undefined,
@@ -5106,6 +5107,7 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
                     .actual_hash = undefined,
                     .has_build_zig = true,
                     .oom_flag = false,
+                    .latest_commit = undefined,
 
                     .module = build_mod,
                 };
@@ -6757,6 +6759,7 @@ const usage_fetch =
     \\  --debug-hash                  Print verbose hash information to stdout
     \\  --save                        Add the fetched package to build.zig.zon
     \\  --save=[name]                 Add the fetched package to build.zig.zon as name
+    \\  --resolve-commit              Before saving, replace the name of a Git branch/tag with its commit SHA
     \\
 ;
 
@@ -6772,6 +6775,7 @@ fn cmdFetch(
     var override_global_cache_dir: ?[]const u8 = try EnvVar.ZIG_GLOBAL_CACHE_DIR.get(arena);
     var debug_hash: bool = false;
     var save: union(enum) { no, yes, name: []const u8 } = .no;
+    var resolve_commit: bool = false;
 
     {
         var i: usize = 0;
@@ -6792,6 +6796,8 @@ fn cmdFetch(
                     save = .yes;
                 } else if (mem.startsWith(u8, arg, "--save=")) {
                     save = .{ .name = arg["--save=".len..] };
+                } else if (mem.eql(u8, arg, "--resolve-commit")) {
+                    resolve_commit = true;
                 } else {
                     fatal("unrecognized parameter: '{s}'", .{arg});
                 }
@@ -6803,6 +6809,9 @@ fn cmdFetch(
         }
     }
 
+    if (resolve_commit and save == .no)
+        warn("'--resolve-commit' has no effect unless used with '--save'", .{});
+
     const path_or_url = opt_path_or_url orelse fatal("missing url or path parameter", .{});
 
     var thread_pool: ThreadPool = undefined;
@@ -6851,6 +6860,7 @@ fn cmdFetch(
         .job_queue = &job_queue,
         .omit_missing_hash_error = true,
         .allow_missing_paths_field = false,
+        .use_latest_commit = resolve_commit,
 
         .package_root = undefined,
         .error_bundle = undefined,
@@ -6859,6 +6869,7 @@ fn cmdFetch(
         .actual_hash = undefined,
         .has_build_zig = false,
         .oom_flag = false,
+        .latest_commit = undefined,
 
         .module = null,
     };
@@ -6915,13 +6926,22 @@ fn cmdFetch(
     var fixups: Ast.Fixups = .{};
     defer fixups.deinit(gpa);
 
+    const saved_path_or_url = if (resolve_commit) blk: {
+        // replace the refspec with the latest commit SHA
+        var uri = try std.Uri.parse(path_or_url);
+        uri.fragment = try std.fmt.allocPrint(arena, "{}", .{
+            std.fmt.fmtSliceHexLower(&fetch.latest_commit.?),
+        });
+        break :blk try std.fmt.allocPrint(arena, "{}", .{uri});
+    } else path_or_url;
+
     const new_node_init = try std.fmt.allocPrint(arena,
         \\.{{
         \\            .url = "{}",
         \\            .hash = "{}",
         \\        }}
     , .{
-        std.zig.fmtEscapes(path_or_url),
+        std.zig.fmtEscapes(saved_path_or_url),
         std.zig.fmtEscapes(&hex_digest),
     });