Fix for loop panic when variable declared inside and used (#207)

* initial enum impl and match

* fix for loop panic when var declared inside  and used

Author: edg-l

examples/for_loop_var.con

@@ -0,0 +1,10 @@
+mod foo {
+    pub fn main() -> i64 {
+        for (let mut i: i32 = 0; i < 10; i = i + 1) {
+            let mut b: i8 = 0;
+            b = b + 1;
+        }
+
+        return 0;
+    }
+}

src/ir/lowering/expressions.rs

@@ -30,7 +30,7 @@ pub(crate) fn lower_expression(
 ) -> Result<(Rvalue, TypeIndex, Span), LoweringError> {
     Ok(match info {
         Expression::Value(info, span) => {
-            debug!("lowering value");
+            debug!("lowering value expr");
             let value = lower_value_expr(builder, info, type_hint)?;
             (value.0, value.1, *span)
         }
@@ -410,7 +410,6 @@ pub(crate) fn find_expression_type(
     fn_builder: &mut FnIrBuilder,
     info: &Expression,
 ) -> Result<Option<TypeIndex>, LoweringError> {
-    debug!("finding expression type");
     Ok(match info {
         Expression::Value(value, _) => match value {
             ValueExpr::ConstBool(_, _) => Some(fn_builder.builder.ir.get_bool_ty()),

src/ir/lowering/statements.rs

@@ -56,9 +56,8 @@ pub(crate) fn lower_statement(
     Ok(())
 }
 
-#[instrument(level = "debug", skip_all, fields(name, variant))]
+#[instrument(level = "debug", skip_all, fields(name, variant, ty))]
 fn lower_let(builder: &mut FnIrBuilder, info: &LetStmt) -> Result<(), LoweringError> {
-    debug!("begin lowering let");
     match &info.target {
         LetStmtTarget::Simple { id: name, r#type } => {
             tracing::Span::current().record("name", &name.name);
@@ -814,6 +813,10 @@ fn lower_for(builder: &mut FnIrBuilder, info: &ForStmt) -> Result<(), LoweringEr
     // keep idx for switch targets
     let first_then_block_idx = builder.body.basic_blocks.len();
 
+    for stmt in &info.block_stmts {
+        get_locals(builder, stmt)?;
+    }
+
     for stmt in &info.block_stmts {
         lower_statement(builder, stmt, builder.body.locals[builder.ret_local].ty)?;
     }

tests/examples.rs

@@ -34,6 +34,7 @@ mod common;
 #[test_case(include_str!("../examples/malloc.con"), "malloc", false, 5 ; "malloc.con")]
 #[test_case(include_str!("../examples/while_if_false.con"), "while_if_false", false, 7 ; "while_if_false.con")]
 #[test_case(include_str!("../examples/if_if_false.con"), "if_if_false", false, 7 ; "if_if_false.con")]
+#[test_case(include_str!("../examples/for_loop_var.con"), "for", false, 0 ; "for_loop_var.con")]
 #[test_case(include_str!("../examples/for.con"), "for", false, 10 ; "for.con")]
 #[test_case(include_str!("../examples/for_while.con"), "for_while", false, 10 ; "for_while.con")]
 #[test_case(include_str!("../examples/arrays.con"), "arrays", false, 5 ; "arrays.con")]