Fix Rust build example configuration handling

components/rust/core/SConscript

@@ -11,6 +11,7 @@ from build_support import (
     verify_rust_toolchain,
     ensure_rust_target_installed,
     cargo_build_staticlib,
+    get_staticlib_link_name,
     clean_rust_build,
 )
 def _has(sym: str) -> bool:
@@ -20,10 +21,27 @@ def _has(sym: str) -> bool:
         return bool(GetDepend(sym))
 
 
-# Source files – MSH command glue
-src = ['rust_cmd.c']
+group = []
+if not _has('RT_RUST_CORE'):
+    Return('group')
+
+
+def get_staticlib_link_name_from_artifact(lib_path):
+    """Derive the link name from the actual staticlib artifact file name."""
+    artifact_name = os.path.basename(os.fspath(lib_path))
+    if artifact_name.startswith("lib") and artifact_name.endswith(".a"):
+        return artifact_name[3:-2]
+    return None
+
+
+# Source files – MSH command glue.
+# rust_cmd.c references rust_init(), which is only provided by the Rust core
+# static library. It must only enter the build when that library is actually
+# produced; otherwise the C link stage fails with 'undefined reference to
+# rust_init' instead of failing/skipping cleanly at the Rust build step.
 LIBS = []
 LIBPATH = []
+include_rust_cmd = False
 
 if GetOption('clean'):
     # Register Rust artifacts for cleaning
@@ -33,9 +51,12 @@ if GetOption('clean'):
         Clean('.', rust_build_dir)
     else:
         print('No rust build artifacts to clean')
+    # Keep rust_cmd.c in the group during clean so its object is cleaned too.
+    include_rust_cmd = True
 else:
     if verify_rust_toolchain():
         import rtconfig
+        rust_build_dir = clean_rust_build(Dir('#').abspath)
 
         target = detect_rust_target(_has, rtconfig)
         if not target:
@@ -44,28 +65,39 @@ else:
             print(f'Detected Rust target: {target}')
 
             # Optional hint if target missing
-            ensure_rust_target_installed(target)
-
-            # Build mode and features
-            debug = bool(_has('RUST_DEBUG_BUILD'))
-            features = collect_features(_has)
+            if not ensure_rust_target_installed(target):
+                print('Warning: Rust target is not installed; skipping Rust library build')
+            else:
+                # Build mode and features
+                debug = bool(_has('RUST_DEBUG_BUILD'))
+                features = collect_features(_has)
 
-            rustflags = make_rustflags(rtconfig, target)
-            rust_lib = cargo_build_staticlib(
-                rust_dir=cwd, target=target, features=features, debug=debug, rustflags=rustflags
-            )
+                rustflags = make_rustflags(rtconfig, target)
+                rust_lib = cargo_build_staticlib(
+                    rust_dir=cwd, target=target, features=features, debug=debug, rustflags=rustflags, build_root=rust_build_dir
+                )
 
-            if rust_lib:
-                LIBS = ['rt_rust']
-                LIBPATH = [os.path.dirname(rust_lib)]
-                print('Rust library linked successfully')
-            else:
-                print('Warning: Failed to build Rust library')
+                if rust_lib:
+                    # Derive the link name from the actual artifact so it always
+                    # matches the file that was built. Only fall back to
+                    # re-parsing Cargo.toml when the artifact name does not
+                    # follow the lib<name>.a convention.
+                    link_lib_name = get_staticlib_link_name_from_artifact(rust_lib)
+                    if not link_lib_name:
+                        link_lib_name = get_staticlib_link_name(cwd)
+                    LIBS = [link_lib_name]
+                    LIBPATH = [os.path.dirname(rust_lib)]
+                    include_rust_cmd = True
+                    print('Rust library linked successfully')
+                else:
+                    print('Warning: Failed to build Rust library')
     else:
         print('Warning: Rust toolchain not found')
         print('Please install Rust from https://rustup.rs')
 
-# Define component group for SCons
-group = DefineGroup('rust', src, depend=['RT_USING_RUST'], LIBS=LIBS, LIBPATH=LIBPATH)
+# Only define the component group (with rust_cmd.c) when the Rust core static
+# library was actually produced, so its rust_init() reference always resolves.
+if include_rust_cmd:
+    group = DefineGroup('rust', ['rust_cmd.c'], depend=['RT_USING_RUST', 'RT_RUST_CORE'], LIBS=LIBS, LIBPATH=LIBPATH)
 
 Return('group')

components/rust/examples/application/SConscript

@@ -31,7 +31,7 @@ def load_extended_feature_configs():
 
 group = []
 
-if not _has('RT_RUST_BUILD_APPLICATIONS'):
+if not (_has('RT_RUST_BUILD_APPLICATIONS') or _has('RT_RUST_BUILD_ALL_EXAMPLES')):
     Return('group')
 
 # Load extended feature configurations
@@ -67,4 +67,4 @@ group = DefineGroup(
     LINKFLAGS=LINKFLAGS
 )
 
-Return('group')
+Return('group')

components/rust/examples/component/SConscript

@@ -25,12 +25,11 @@ def _has(sym: str) -> bool:
         return bool(GetDepend(sym))
 
 
-# Early return if Rust or log component is not enabled
 if not _has('RT_USING_RUST'):
     group = []
     Return('group')
 
-if not _has('RUST_LOG_COMPONENT'):
+if not (_has('RT_RUST_BUILD_COMPONENTS') or _has('RT_RUST_BUILD_ALL_EXAMPLES')):
     group = []
     Return('group')
 
@@ -68,4 +67,4 @@ group = DefineGroup(
     LINKFLAGS=LINKFLAGS
 )
 
-Return('group')
+Return('group')

components/rust/examples/modules/SConscript

@@ -1,7 +1,6 @@
 import os
 import sys
 import subprocess
-import toml
 from building import *
 
 cwd = GetCurrentDir()
@@ -25,13 +24,27 @@ sys.path.insert(0, tools_dir)
 
 from build_support import detect_rust_target, ensure_rust_target_installed, clean_rust_build
 
+MODULE_CONFIG_MAP = {
+    'example_lib': 'RT_RUST_MODULE_SIMPLE_MODULE',
+}
+
 def _has(sym: str) -> bool:
     """Helper function to check if a configuration symbol is enabled"""
     try:
         return bool(GetDepend([sym]))
     except Exception:
         return bool(GetDepend(sym))
 
+def should_build_module(module_dir):
+    if _has('RT_RUST_BUILD_ALL_EXAMPLES'):
+        return True
+
+    config = MODULE_CONFIG_MAP.get(os.path.basename(module_dir))
+    if config:
+        return _has(config)
+
+    return True
+
 def detect_target_for_dynamic_modules():
     """
     Detect the appropriate Rust target for dynamic modules.
@@ -58,19 +71,43 @@ def detect_target_for_dynamic_modules():
     print("Error: Unable to detect appropriate Rust target for dynamic modules")
     raise RuntimeError("Target detection failed - no valid target found")
 
+def _decode_cargo_output(output):
+    """Decode cargo stdout/stderr which may be bytes or str."""
+    if output is None:
+        return ""
+    if isinstance(output, bytes):
+        return output.decode(errors="replace")
+    return str(output)
+
 def build_rust_module(module_dir, build_root):
     """Build a Rust dynamic module with automatic target detection"""
     cargo_toml_path = os.path.join(module_dir, 'Cargo.toml')
     if not os.path.exists(cargo_toml_path):
         return [], [], ""
+
+    try:
+        import toml
+    except ImportError:
+        print(f"Warning: Failed to parse {cargo_toml_path}: missing toml module")
+        return [], [], ""
 
-    with open(cargo_toml_path, 'r') as f:
-        cargo_config = toml.load(f)
-
-    module_name = cargo_config['package']['name']
+    try:
+        with open(cargo_toml_path, 'r') as f:
+            cargo_config = toml.load(f)
+        module_name = cargo_config['package']['name']
+        lib_name = cargo_config.get('lib', {}).get('name') or module_name
+        link_lib_name = lib_name.replace('-', '_')
+    except Exception as e:
+        print(f"Warning: Failed to parse module metadata from {cargo_toml_path}: {e}")
+        return [], [], ""
 
     # Detect target automatically based on the current configuration
-    target = detect_target_for_dynamic_modules()
+    try:
+        target = detect_target_for_dynamic_modules()
+    except RuntimeError as e:
+        print(f"Warning: Failed to detect Rust target for module '{module_name}': {e}")
+        return [], [], ""
+
     print(f"Building Rust module '{module_name}' for target: {target}")
 
     # Detect debug mode from rtconfig (same as main rust/SConscript)
@@ -92,7 +129,14 @@ def build_rust_module(module_dir, build_root):
 
     # Set up build environment
     env = os.environ.copy()
-    env['RUSTFLAGS'] = rustflags
+    previous_rustflags = env.get('RUSTFLAGS', '').strip()
+    new_rustflags = rustflags.strip() if rustflags else ''
+    if previous_rustflags and new_rustflags:
+        env['RUSTFLAGS'] = f'{previous_rustflags} {new_rustflags}'
+    elif new_rustflags:
+        env['RUSTFLAGS'] = new_rustflags
+    elif previous_rustflags:
+        env['RUSTFLAGS'] = previous_rustflags
     env['CARGO_TARGET_DIR'] = build_root
 
     # Build the module with configurable parameters using dictionary configuration
@@ -116,12 +160,30 @@ def build_rust_module(module_dir, build_root):
     try:
         subprocess.run(build_cmd, cwd=module_dir, env=env, check=True, capture_output=True)
         lib_dir = os.path.join(build_root, target, build_mode)
-        return [module_name], [lib_dir], ""
-    except subprocess.CalledProcessError:
+        artifact_name = f"lib{link_lib_name}.so"
+        artifact_path = os.path.join(lib_dir, artifact_name)
+        if not os.path.isfile(artifact_path) or os.path.getsize(artifact_path) == 0:
+            print(f"Warning: Rust module artifact not found, is not a file, or is empty: {artifact_path}")
+            return [], [], ""
+        return [link_lib_name], [lib_dir], ""
+    except FileNotFoundError:
+        print("Error: cargo executable not found. Please install Rust/Cargo and ensure it is in PATH.")
+        return [], [], ""
+    except subprocess.CalledProcessError as e:
+        print(f"Error: Failed to build Rust module: {e}")
+        stdout = _decode_cargo_output(getattr(e, "stdout", None) or getattr(e, "output", None)).strip()
+        stderr = _decode_cargo_output(getattr(e, "stderr", None)).strip()
+        if stdout:
+            print(stdout)
+        if stderr:
+            print(stderr)
         return [], [], ""
 
 # Check dependencies
-if not _has('RT_RUST_BUILD_MODULES'):
+if not _has('RT_USING_MODULE'):
+    Return([])
+
+if not (_has('RT_RUST_BUILD_MODULES') or _has('RT_RUST_BUILD_ALL_EXAMPLES')):
     Return([])
 
 build_root = os.path.join(Dir('#').abspath, "build", "rust_modules")
@@ -142,7 +204,7 @@ else:
     modules_built = []
     for item in os.listdir(cwd):
         item_path = os.path.join(cwd, item)
-        if os.path.isdir(item_path) and os.path.exists(os.path.join(item_path, 'Cargo.toml')):
+        if os.path.isdir(item_path) and os.path.exists(os.path.join(item_path, 'Cargo.toml')) and should_build_module(item_path):
             result = build_rust_module(item_path, build_root)
             if result[0]:
                 modules_built.extend(result[0])
@@ -151,9 +213,9 @@ else:
         print(f"Successfully built {len(modules_built)} Rust dynamic module(s): {', '.join(modules_built)}")
 
 group = DefineGroup(
-    'rust_modules', 
-    [], 
-    depend=['RT_RUST_BUILD_MODULES']
+    'rust_modules',
+    [],
+    depend=['RT_USING_MODULE']
 )
 
-Return('group')
+Return('group')

components/rust/examples/modules/example_lib/Cargo.toml

@@ -9,4 +9,4 @@ edition = "2024"
 crate-type = ["cdylib"]
 
 [dependencies]
-rt-rust = { path = "../../.." }
+rt-rust = { path = "../../../core" }