From ea044a4b829a03861823bac7bbef8e28e4c54af6 Mon Sep 17 00:00:00 2001
From: Techatrix <techatrix@mailbox.org>
Date: Wed, 27 May 2026 18:54:08 +0200
Subject: [PATCH] std.Build: do not clobber properties of a package like named
 modules

Repeated calls to `addModule` with the same name will override the
module that is visible to dependants which is likely unintentional.
Instead it should assert that no existing module has already been added
with the given name.

The same issue applies to `addNamedWriteFiles` and `addNamedLazyPath`.
---
 lib/std/Build.zig | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/lib/std/Build.zig b/lib/std/Build.zig
index 70ef8d0e2088682fa9e5049422ea13860c30e717..cebc691fad630289599102f08f07252828c9a4f0 100644
--- a/lib/std/Build.zig
+++ b/lib/std/Build.zig
@@ -830,7 +830,17 @@ pub fn addModule(b: *Build, name: []const u8, options: Module.CreateOptions) *Mo
     const graph = b.graph;
     const arena = graph.arena;
     const module = Module.create(b, options);
-    b.modules.put(arena, graph.dupeString(name), module) catch @panic("OOM");
+    const gop = b.modules.getOrPutValue(
+        arena,
+        graph.dupeString(name),
+        module,
+    ) catch @panic("OOM");
+    if (gop.found_existing) {
+        panic(
+            "A module with the name '{s}' has already been added to the package. Consider creating a private module with std.Build.createModule",
+            .{name},
+        );
+    }
     return module;
 }
 
@@ -992,13 +1002,33 @@ pub fn addWriteFile(b: *Build, file_path: []const u8, data: []const u8) *Step.Wr
 pub fn addNamedWriteFiles(b: *Build, name: []const u8) *Step.WriteFile {
     const graph = b.graph;
     const wf = Step.WriteFile.create(b);
-    b.named_writefiles.put(graph.arena, graph.dupeString(name), wf) catch @panic("OOM");
+    const gop = b.named_writefiles.getOrPutValue(
+        graph.arena,
+        graph.dupeString(name),
+        wf,
+    ) catch @panic("OOM");
+    if (gop.found_existing) {
+        panic(
+            "A WriteFile step with the name '{s}' has already been added to the package. Consider creating a private WriteFile step with std.Build.addWriteFiles",
+            .{name},
+        );
+    }
     return wf;
 }
 
 pub fn addNamedLazyPath(b: *Build, name: []const u8, lp: LazyPath) void {
     const graph = b.graph;
-    b.named_lazy_paths.put(graph.arena, graph.dupeString(name), lp.dupe(graph)) catch @panic("OOM");
+    const gop = b.named_lazy_paths.getOrPutValue(
+        graph.arena,
+        graph.dupeString(name),
+        lp.dupe(graph),
+    ) catch @panic("OOM");
+    if (gop.found_existing) {
+        panic(
+            "A LazyPath with the name '{s}' has already been added to the package.",
+            .{name},
+        );
+    }
 }
 
 /// Creates a step for mutating files inside a temporary directory created lazily
-- 
2.54.0