From 6cecad145d569bf9794760ca13bd2bf479a357c7 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 14 Oct 2026 17:38:43 -0700
Subject: [PATCH] Maker: fix use case when --fork matches 2 or more pkgs

Previously this always caused a compilation failure because it would
correctly substitute multiple packages with the provided forked package,
however, this ends up constructing a zig build-exe command line for the
configurer that included multiple differnt modules that used the same
files.

Closes #31677
---
 lib/compiler/Maker.zig       | 37 ++++++++++++++++++++++++++----------
 lib/compiler/Maker/Fetch.zig | 16 ++++++++++++----
 2 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/lib/compiler/Maker.zig b/lib/compiler/Maker.zig
index d0f8117ce8eaf9a1f7e34f84ba97b6740abad397..829c28ff55bcd4e71bc336caca0c7623fe4a4c04 100644
--- a/lib/compiler/Maker.zig
+++ b/lib/compiler/Maker.zig
@@ -1444,17 +1444,34 @@ fn configure(graph: *Graph, options: ConfigureOptions) !ScannedConfig {
                             // The first one is a dummy package for the current project.
                             continue;
                         }
-                        if (!f.has_build_zig)
-                            continue;
-                        const hash_slice = try arena.dupe(u8, hash.toSlice());
+                        if (!f.has_build_zig) continue;
 
-                        const m = try arena.create(CliModule);
-                        m.* = .{
-                            .root_path = try f.package_root.toString(arena),
-                            .name = hash_slice,
-                        };
-                        deps_mod.deps.putAssumeCapacityNoClobber(hash_slice, m);
-                        f.cli_module = m;
+                        const project_id: Package.ProjectId = .init(f.manifest.name, f.manifest.id);
+                        if (fork_set.getKeyPtrAdapted(project_id, @as(Fetch.JobQueue.Fork.Adapter, .{}))) |fork| {
+                            const path = try fork.path.toString(arena);
+                            const gop = deps_mod.deps.getOrPutAssumeCapacity(path);
+                            if (gop.found_existing) {
+                                assert(fork.uses > 1);
+                                f.cli_module = gop.value_ptr.*;
+                            } else {
+                                const m = try arena.create(CliModule);
+                                m.* = .{
+                                    .root_path = try f.package_root.toString(arena),
+                                    .name = path,
+                                };
+                                gop.value_ptr.* = m;
+                                f.cli_module = m;
+                            }
+                        } else {
+                            const hash_slice = try arena.dupe(u8, hash.toSlice());
+                            const m = try arena.create(CliModule);
+                            m.* = .{
+                                .root_path = try f.package_root.toString(arena),
+                                .name = hash_slice,
+                            };
+                            deps_mod.deps.putAssumeCapacityNoClobber(hash_slice, m);
+                            f.cli_module = m;
+                        }
                     }
 
                     // Each build.zig module needs access to each of its dependencies' build.zig modules by
diff --git a/lib/compiler/Maker/Fetch.zig b/lib/compiler/Maker/Fetch.zig
index 0da66401f92fb09d61961db830ad4a0a7776630d..9fa9b121399b55d5745172bda914b1dc3a87a206 100644
--- a/lib/compiler/Maker/Fetch.zig
+++ b/lib/compiler/Maker/Fetch.zig
@@ -290,10 +290,18 @@ pub const JobQueue = struct {
             , .{std.fmt.alt(fetch.package_root, .formatEscapeString)});
 
             if (fetch.has_build_zig) {
-                try w.print(
-                    \\        pub const build_zig = @import("{f}");
-                    \\
-                , .{std.zig.fmtString(hash_slice)});
+                const project_id: Package.ProjectId = .init(fetch.manifest.name, fetch.manifest.id);
+                if (jq.fork_set.getKeyPtrAdapted(project_id, @as(JobQueue.Fork.Adapter, .{}))) |fork| {
+                    try w.print(
+                        \\        pub const build_zig = @import({qf});
+                        \\
+                    , .{fork.path});
+                } else {
+                    try w.print(
+                        \\        pub const build_zig = @import({q});
+                        \\
+                    , .{hash_slice});
+                }
             }
 
             if (fetch.have_manifest) {
-- 
2.54.0