From 0967550f5b2bc46442f65b0d1e3682144736aa5b Mon Sep 17 00:00:00 2001
From: Tom French <tom@tomfren.ch>
Date: Mon, 2 Sep 2024 21:05:53 +0100
Subject: [PATCH] feat: implement `str_as_bytes` in the `comptime` interpreter

---
 .../src/hir/comptime/interpreter/builtin.rs   | 27 +++++++++++++++++++
 .../comptime_str_as_bytes/Nargo.toml          |  7 +++++
 .../comptime_str_as_bytes/src/main.nr         |  9 +++++++
 3 files changed, 43 insertions(+)
 create mode 100644 test_programs/compile_success_empty/comptime_str_as_bytes/Nargo.toml
 create mode 100644 test_programs/compile_success_empty/comptime_str_as_bytes/src/main.nr

diff --git a/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs b/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
index 7a196d98f52..e5b098b41ed 100644
--- a/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
+++ b/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
@@ -126,6 +126,7 @@ impl<'local, 'context> Interpreter<'local, 'context> {
             "slice_push_back" => slice_push_back(interner, arguments, location),
             "slice_push_front" => slice_push_front(interner, arguments, location),
             "slice_remove" => slice_remove(interner, arguments, location, call_stack),
+            "str_as_bytes" => str_as_bytes(interner, arguments, location),
             "struct_def_as_type" => struct_def_as_type(interner, arguments, location),
             "struct_def_fields" => struct_def_fields(interner, arguments, location),
             "struct_def_generics" => struct_def_generics(interner, arguments, location),
@@ -242,6 +243,32 @@ fn slice_push_back(
     Ok(Value::Slice(values, typ))
 }
 
+fn str_as_bytes(
+    interner: &NodeInterner,
+    arguments: Vec<(Value, Location)>,
+    location: Location,
+) -> IResult<Value> {
+    let (string, string_location) = check_one_argument(arguments, location)?;
+
+    match string {
+        Value::String(string) => {
+            let string_as_bytes = string.as_bytes();
+            let bytes_vector: Vec<Value> = string_as_bytes.iter().cloned().map(Value::U8).collect();
+            let byte_array_type = Type::Array(
+                Box::new(Type::Constant(string_as_bytes.len() as u32)),
+                Box::new(Type::Integer(Signedness::Unsigned, IntegerBitSize::Eight)),
+            );
+            Ok(Value::Array(bytes_vector.into(), byte_array_type))
+        }
+        value => {
+            let type_var = Box::new(interner.next_type_variable());
+            let expected = Type::Array(type_var.clone(), type_var);
+            let actual = value.get_type().into_owned();
+            Err(InterpreterError::TypeMismatch { expected, actual, location: string_location })
+        }
+    }
+}
+
 /// fn as_type(self) -> Type
 fn struct_def_as_type(
     interner: &NodeInterner,
diff --git a/test_programs/compile_success_empty/comptime_str_as_bytes/Nargo.toml b/test_programs/compile_success_empty/comptime_str_as_bytes/Nargo.toml
new file mode 100644
index 00000000000..f387e0e393a
--- /dev/null
+++ b/test_programs/compile_success_empty/comptime_str_as_bytes/Nargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "comptime_str_as_bytes"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.24.0"
+
+[dependencies]
diff --git a/test_programs/compile_success_empty/comptime_str_as_bytes/src/main.nr b/test_programs/compile_success_empty/comptime_str_as_bytes/src/main.nr
new file mode 100644
index 00000000000..eefea67100f
--- /dev/null
+++ b/test_programs/compile_success_empty/comptime_str_as_bytes/src/main.nr
@@ -0,0 +1,9 @@
+fn main() {
+    comptime
+    {
+        let hello_world_string = "hello world";
+        let hello_world_bytes: [u8; 11] = [0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64];
+
+        assert_eq(hello_world_string.as_bytes(), hello_world_bytes);
+    }
+}