Prevent var def in child scope when name already taken by parent scope

Fixes #275
ethereum · Mar 19, 2021 · e55cbbf · e55cbbf
1 parent 7d2e6f5
commit e55cbbf
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diff --git a/analyzer/src/namespace/scopes.rs b/analyzer/src/namespace/scopes.rs
@@ -306,6 +306,9 @@ impl BlockScope {
 
     /// Add a variable to the block scope.
     pub fn add_var(&mut self, name: &str, typ: FixedSize) -> Result<(), SemanticError> {
+        if self.get_variable_def(name).is_some() {
+            return Err(SemanticError::already_defined());
+        }
         match self.variable_defs.entry(name.to_owned()) {
             Entry::Occupied(_) => Err(SemanticError::already_defined()),
             Entry::Vacant(e) => {

diff --git a/compiler/tests/compile_errors.rs b/compiler/tests/compile_errors.rs
@@ -20,6 +20,7 @@ use std::fs;
     case("duplicate_method_in_contract.fe", "AlreadyDefined"),
     case("duplicate_struct_in_module.fe", "AlreadyDefined"),
     case("duplicate_typedef_in_module.fe", "AlreadyDefined"),
+    case("duplicate_var_in_child_scope.fe", "AlreadyDefined"),
     case("duplicate_var_in_contract_method.fe", "AlreadyDefined"),
     case("external_call_type_error.fe", "TypeError"),
     case("external_call_wrong_number_of_params.fe", "WrongNumberOfParams"),

diff --git a/compiler/tests/fixtures/compile_errors/duplicate_var_in_child_scope.fe b/compiler/tests/fixtures/compile_errors/duplicate_var_in_child_scope.fe
@@ -0,0 +1,6 @@
+contract Foo:
+    pub def bar():
+        my_array: u256[3]
+        sum: u256 = 0
+        for i in my_array:
+            sum: u256 = 0
diff --git a/newsfragments/317.bugfix.md b/newsfragments/317.bugfix.md
@@ -37,3 +37,16 @@ struct SomeStruct:
     some_field: u8
     some_field: u8
 ```
+
+
+Prevent variable definition in child scope when name already taken in parent scope.
+
+Example that now produces a compile time error:
+
+```
+pub def bar():
+    my_array: u256[3]
+    sum: u256 = 0
+    for i in my_array:
+        sum: u256 = 0
+```