RustPython · youknowone · Jul 7, 2025 · Jul 7, 2025 · Jul 7, 2025 · gemini-code-assist
diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
@@ -21,7 +21,7 @@ RustPython is a Python 3 interpreter written in Rust, implementing Python 3.13.0
   - `parser/` - Parser for converting Python source to AST
   - `core/` - Bytecode representation in Rust structures
   - `codegen/` - AST to bytecode compiler
-- `Lib/` - CPython's standard library in Python (copied from CPython)
+- `Lib/` - CPython's standard library in Python (copied from CPython). **IMPORTANT**: Do not edit this directory directly; The only allowed operation is copying files from CPython.
 - `derive/` - Rust macros for RustPython
 - `common/` - Common utilities
 - `extra_tests/` - Integration tests and snippets

diff --git a/extra_tests/snippets/builtin_eval.py b/extra_tests/snippets/builtin_eval.py
@@ -2,3 +2,76 @@
 
 code = compile("5+3", "x.py", "eval")
 assert eval(code) == 8
+
+# Test that globals must be a dict
+import collections
+
+# UserDict is a mapping but not a dict - should fail in eval
+user_dict = collections.UserDict({"x": 5})
+try:
+    eval("x", user_dict)
+    assert False, "eval with UserDict globals should fail"
+except TypeError as e:
+    # CPython: "globals must be a real dict; try eval(expr, {}, mapping)"
+    assert "globals must be a real dict" in str(e), e
+
+# Non-mapping should have different error message
+try:
+    eval("x", 123)
+    assert False, "eval with int globals should fail"
+except TypeError as e:
+    # CPython: "globals must be a dict"
+    assert "globals must be a dict" in str(e)
+    assert "real dict" not in str(e)
+
+# List is not a mapping
+try:
+    eval("x", [])
+    assert False, "eval with list globals should fail"
+except TypeError as e:
+    assert "globals must be a real dict" in str(e), e
-    assert "globals must be a real dict" in str(e), e
+    assert "globals must be a dict" in str(e)
+    assert "real dict" not in str(e), e
-    assert "globals must be a real dict" in str(e), e
+    assert "globals must be a dict" in str(e)
+    assert "real dict" not in str(e), e
+
+# Regular dict should work
+assert eval("x", {"x": 42}) == 42
+
+# None should use current globals
+x = 100
+assert eval("x", None) == 100
+
+# Test locals parameter
+# Locals can be any mapping (unlike globals which must be dict)
+assert eval("y", {"y": 1}, user_dict) == 1  # UserDict as locals is OK
+
+# But locals must still be a mapping
+try:
+    eval("x", {"x": 1}, 123)
+    assert False, "eval with int locals should fail"
+except TypeError as e:
+    # This error is handled by ArgMapping validation
+    assert "not a mapping" in str(e) or "locals must be a mapping" in str(e)
+
+# Test that __builtins__ is added if missing
+globals_without_builtins = {"x": 5}
+result = eval("x", globals_without_builtins)
+assert result == 5
+assert "__builtins__" in globals_without_builtins
+
+# Test with both globals and locals
+assert eval("x + y", {"x": 10}, {"y": 20}) == 30
+
+# Test that when globals is None and locals is provided, it still works
+assert eval("x + y", None, {"x": 1, "y": 2}) == 3
+
+
+# Test code object with free variables
+def make_closure():
+    z = 10
+    return compile("x + z", "<string>", "eval")
+
+
+closure_code = make_closure()
+try:
+    eval(closure_code, {"x": 5})
+    assert False, "eval with code containing free variables should fail"
+except NameError as e:
+    pass
diff --git a/vm/src/stdlib/builtins.rs b/vm/src/stdlib/builtins.rs
@@ -249,24 +249,56 @@ mod builtins {
     #[derive(FromArgs)]
     struct ScopeArgs {
         #[pyarg(any, default)]
-        globals: Option<PyDictRef>,
+        globals: Option<PyObjectRef>,
         #[pyarg(any, default)]
         locals: Option<ArgMapping>,
     }
 
     impl ScopeArgs {
-        fn make_scope(self, vm: &VirtualMachine) -> PyResult<crate::scope::Scope> {
+        fn make_scope(
+            self,
+            vm: &VirtualMachine,
+            func_name: &'static str,
+        ) -> PyResult<crate::scope::Scope> {
+            fn validate_globals_dict(
+                globals: &PyObjectRef,
+                vm: &VirtualMachine,
+                func_name: &'static str,
+            ) -> PyResult<()> {
+                if !globals.fast_isinstance(vm.ctx.types.dict_type) {
+                    return Err(match func_name {
+                        "eval" => {
+                            let is_mapping = crate::protocol::PyMapping::check(globals);
+                            vm.new_type_error(if is_mapping {
+                                "globals must be a real dict; try eval(expr, {}, mapping)"
+                                    .to_owned()
+                            } else {
+                                "globals must be a dict".to_owned()
+                            })
+                        }
+                        "exec" => vm.new_type_error(format!(
+                            "exec() globals must be a dict, not {}",
+                            globals.class().name()
+                        )),
+                        _ => vm.new_type_error("globals must be a dict".to_owned()),
+                    });
+                }
+                Ok(())
+            }
+
             let (globals, locals) = match self.globals {
                 Some(globals) => {
+                    validate_globals_dict(&globals, vm, func_name)?;
+
+                    let globals = PyDictRef::try_from_object(vm, globals)?;
                     if !globals.contains_key(identifier!(vm, __builtins__), vm) {
                         let builtins_dict = vm.builtins.dict().into();
                         globals.set_item(identifier!(vm, __builtins__), builtins_dict, vm)?;
                     }
                     (
                         globals.clone(),
-                        self.locals.unwrap_or_else(|| {
-                            ArgMapping::try_from_object(vm, globals.into()).unwrap()
-                        }),
+                        self.locals
+                            .unwrap_or_else(|| ArgMapping::from_dict_exact(globals.clone())),
                     )
                 }
                 None => (
@@ -290,6 +322,8 @@ mod builtins {
         scope: ScopeArgs,
         vm: &VirtualMachine,
     ) -> PyResult {
+        let scope = scope.make_scope(vm, "eval")?;
+
         // source as string
         let code = match source {
             Either::A(either) => {
@@ -323,18 +357,17 @@ mod builtins {
         scope: ScopeArgs,
         vm: &VirtualMachine,
     ) -> PyResult {
+        let scope = scope.make_scope(vm, "exec")?;
         run_code(vm, source, scope, crate::compiler::Mode::Exec, "exec")
     }
 
     fn run_code(
         vm: &VirtualMachine,
         source: Either<PyStrRef, PyRef<crate::builtins::PyCode>>,
-        scope: ScopeArgs,
+        scope: crate::scope::Scope,
         #[allow(unused_variables)] mode: crate::compiler::Mode,
         func: &str,
     ) -> PyResult {
-        let scope = scope.make_scope(vm)?;
-
         // Determine code object:
         let code_obj = match source {
             #[cfg(feature = "rustpython-compiler")]