fix: cast signed to u1

compiler/noirc_evaluator/src/ssa/ssa_gen/context.rs

@@ -724,7 +724,10 @@ impl<'a> FunctionContext<'a> {
                 Type::Numeric(NumericType::Signed { bit_size: incoming_type_size }),
                 NumericType::Unsigned { bit_size: target_type_size },
             ) => {
-                if *incoming_type_size != target_type_size {
+                // If the target type size is 1 it means it's a cast to u1. In that case
+                // there's no need to cast to i1 first (which actually isn't a valid type),
+                // because the result will be the least significant bit anyway.
+                if *incoming_type_size != target_type_size && target_type_size != 1 {
                     value = self.insert_safe_cast(
                         value,
                         NumericType::signed(target_type_size),

test_programs/compile_success_empty/cast_signed_to_u1/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "cast_signed_to_u1"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.30.0"
+
+[dependencies]

test_programs/compile_success_empty/cast_signed_to_u1/src/main.nr

@@ -0,0 +1,4 @@
+fn main() {
+    let x: i32 = 1;
+    let _ = x as u1;
+}