From 2fdc8a5510550ec3187db6c167713751bed17a6c Mon Sep 17 00:00:00 2001
From: Andrzej J Skalski <gitstuff@s5i.ch>
Date: Sun, 28 Dec 2025 10:37:40 -0300
Subject: [PATCH 1/2] fix to fix

---
 build_defs/rust.build_defs | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/build_defs/rust.build_defs b/build_defs/rust.build_defs
index 77c31e2..94d2072 100644
--- a/build_defs/rust.build_defs
+++ b/build_defs/rust.build_defs
@@ -218,15 +218,19 @@ def rust_binary(name:str, main:str, deps:list=None, edition:str='2021', features
     
     # All this really does is ensure that rust_proto_libraries build before the pre_build function.
     # TODO: is there a better way of doing this?
-    collect_deps = genrule(
-        name = f"_{name}#target_deps",
-        cmd = [
-            f"mkdir $OUTS",
-            f"mv $SRCS $OUTS",
-        ],
-        srcs = deps,
-        outs = [target_dir],
-    )
+    if deps:
+        collect_deps = [genrule(
+            name = f"_{name}#target_deps",
+            cmd = [
+                f"mkdir $OUTS",
+                f"mv $SRCS $OUTS",
+            ],
+            srcs = deps,
+            outs = [target_dir],
+        )]
+    else:
+        collect_deps = []
+
     cmd, tools = _rustc_cmds(
         crate_name=name,
         edition=edition,
@@ -240,7 +244,7 @@ def rust_binary(name:str, main:str, deps:list=None, edition:str='2021', features
         binary = True,
         outs = [name],
         cmd = cmd,
-        deps = deps + [collect_deps],
+        deps = deps + collect_deps,
         visibility = visibility,
         requires = ['rust'],
         tools = tools,

From d25944d27055297435b458d5c8057f14966e89d2 Mon Sep 17 00:00:00 2001
From: Andrzej J Skalski <gitstuff@s5i.ch>
Date: Mon, 29 Dec 2025 13:45:30 -0300
Subject: [PATCH 2/2] fixed empty deps and added an example

---
 build_defs/rust.build_defs       | 4 ++--
 examples/hello_world/BUILD       | 8 ++++++++
 examples/hello_world/src/main.rs | 4 ++++
 3 files changed, 14 insertions(+), 2 deletions(-)
 create mode 100644 examples/hello_world/BUILD
 create mode 100644 examples/hello_world/src/main.rs

diff --git a/build_defs/rust.build_defs b/build_defs/rust.build_defs
index 94d2072..b5aaf2a 100644
--- a/build_defs/rust.build_defs
+++ b/build_defs/rust.build_defs
@@ -182,7 +182,7 @@ def rust_library(name:str, root:str, crate_name:str="", modules:list=None, deps:
     )
 
 
-def rust_binary(name:str, main:str, deps:list=None, edition:str='2021', features:list=None, build_root:str=None, build_deps:list|dict=None, build_compile_env:dict=None, build_run_env:dict=None, target_dir:str="target/debug/deps", visibility:list=None, _os:str=None, _arch:str=None):
+def rust_binary(name:str, main:str, deps:list=[], edition:str='2021', features:list=None, build_root:str=None, build_deps:list|dict=None, build_compile_env:dict=None, build_run_env:dict=None, target_dir:str="target/debug/deps", visibility:list=None, _os:str=None, _arch:str=None):
     """Defines a build rule for a Rust standalone binary.
 
     Args:
@@ -218,7 +218,7 @@ def rust_binary(name:str, main:str, deps:list=None, edition:str='2021', features
     
     # All this really does is ensure that rust_proto_libraries build before the pre_build function.
     # TODO: is there a better way of doing this?
-    if deps:
+    if len(deps) > 0:
         collect_deps = [genrule(
             name = f"_{name}#target_deps",
             cmd = [
diff --git a/examples/hello_world/BUILD b/examples/hello_world/BUILD
new file mode 100644
index 0000000..f29d699
--- /dev/null
+++ b/examples/hello_world/BUILD
@@ -0,0 +1,8 @@
+subinclude("//build_defs:rust")
+
+rust_binary(
+    name = "hello_world",
+    main = "src/main.rs",
+    edition = "2021",
+)
+
diff --git a/examples/hello_world/src/main.rs b/examples/hello_world/src/main.rs
new file mode 100644
index 0000000..24e4cf8
--- /dev/null
+++ b/examples/hello_world/src/main.rs
@@ -0,0 +1,4 @@
+fn main() {
+    println!("Hello, world!");
+}
+