fix: initialise strings as u8 array

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

@@ -40,7 +40,7 @@
 /// This function will generate the SSA but does not perform any optimizations on it.
 pub(crate) fn generate_ssa(program: Program) -> Result<Ssa, RuntimeError> {
     // see which parameter has call_data/return_data attribute
     let is_databus = DataBusBuilder::is_databus(&program.main_function_signature);
 
     let is_return_data = matches!(program.return_visibility, Visibility::DataBus);
 
@@ -61,7 +61,7 @@
     );
 
     // Generate the call_data bus from the relevant parameters. We create it *before* processing the function body
     let call_data = function_context.builder.call_data_bus(is_databus);
 
     function_context.codegen_function_body(&main.body)?;
 
@@ -88,7 +88,7 @@
                 call_stack.clear();
                 call_stack.push_back(return_location);
                 // replace the returned values with the return data array
                 if let Some(return_data_bus) = return_data.databus {
                     return_values.clear();
                     return_values.push(return_data_bus);
                 }
@@ -224,8 +224,9 @@
     }
 
     fn codegen_string(&mut self, string: &str) -> Values {
-        let elements =
-            vecmap(string.as_bytes(), |byte| self.builder.field_constant(*byte as u128).into());
+        let elements = vecmap(string.as_bytes(), |byte| {
+            self.builder.numeric_constant(*byte as u128, Type::unsigned(8)).into()
+        });
         let typ = Self::convert_non_tuple_type(&ast::Type::String(elements.len() as u64));
         self.codegen_array(elements, typ)
     }
@@ -447,7 +448,7 @@
     ///   br loop_entry(v0)
     /// loop_entry(i: Field):
     ///   v2 = lt i v1
     ///   brif v2, then: loop_body, else: loop_end
     /// loop_body():
     ///   v3 = ... codegen body ...
     ///   v4 = add 1, i
@@ -501,7 +502,7 @@
     /// For example, the expression `if cond { a } else { b }` is codegen'd as:
     ///
     ///   v0 = ... codegen cond ...
     ///   brif v0, then: then_block, else: else_block
     /// then_block():
     ///   v1 = ... codegen a ...
     ///   br end_if(v1)
@@ -514,7 +515,7 @@
     /// As another example, the expression `if cond { a }` is codegen'd as:
     ///
     ///   v0 = ... codegen cond ...
     ///   brif v0, then: then_block, else: end_block
     /// then_block:
     ///   v1 = ... codegen a ...
     ///   br end_if()

test_programs/execution_success/regression_3635/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "regression_3635"
+version = "0.1.0"
+type = "bin"
+authors = [""]
+
+[dependencies]

test_programs/execution_success/regression_3635/src/main.nr

@@ -0,0 +1,10 @@
+// Test unsafe integer multiplication with overflow: 12^8 = 429 981 696
+// The circuit should handle properly the growth of the bit size
+use dep::std;
+
+fn main() {
+    let x: u8 = 0x61;
+    let y: u8 = "a".as_bytes()[0];
+    assert_eq(x, y);
+    assert_eq(x >> 1, y >> 1);
+}