Lower bool literals to Rust

Author: olwang

README.md

@@ -418,7 +418,7 @@ If a lowered package contains `fn main() -> Unit` or `fn main() -> Result<Unit,
 
 `rss verify-rust <file.rss> --out-dir <directory>` keeps the generated package used for backend checking, including `rsscript-source-map.json`, so unmappable rustc diagnostics can be inspected against the generated Rust.
 
-The first observable runtime boundaries are `Log.write(message: read String)` and `Assert.equal(left: read String, right: read String)`, which lower to explicit runtime hooks. Simple core operations such as `String.concat(left: read String, right: read String)` keep RSScript `.rssi` signatures for checking and review, but lower directly to Rust standard-library expressions. Built-in numeric and comparison operators lower to the corresponding Rust operators; user-defined operator overloading remains forbidden.
+The first observable runtime boundaries are `Log.write(message: read String)` and `Assert.equal(left: read String, right: read String)`, which lower to explicit runtime hooks. Simple core operations such as `String.concat(left: read String, right: read String)` keep RSScript `.rssi` signatures for checking and review, but lower directly to Rust standard-library expressions. Built-in boolean literals, numeric operators, and comparison operators lower to the corresponding Rust literals and operators; user-defined operator overloading remains forbidden.
 
 Smallest runnable example:
 

examples/bool_literals.rss

@@ -0,0 +1,7 @@
+fn main() -> Unit {
+    let _ = true != false
+    if true {
+        Log.write(message: read "bool literals ran")
+    }
+    return Unit
+}

src/rust_lower.rs

@@ -1080,6 +1080,8 @@ fn is_resource_pool_borrow_expr(expr: &Expr) -> bool {
 fn lower_builtin_value_ident(name: &str) -> Option<&'static str> {
     match name {
         "Unit" => Some("()"),
+        "true" => Some("true"),
+        "false" => Some("false"),
         "None" => Some("None"),
         _ => None,
     }

tests/checker.rs

@@ -354,6 +354,23 @@ fn main() -> Unit {
     assert!(rust.contains("let greater_equal = product >= quotient;"));
 }
 
+#[test]
+fn rust_lowering_maps_bool_literals_to_rust_literals() {
+    let source = r#"
+fn main() -> Unit {
+    let enabled = true
+    let disabled = false
+    let changed = enabled != disabled
+    return Unit
+}
+"#;
+    let rust = lower_source_to_rust("bool.rss", source).expect("source should lower");
+
+    assert!(rust.contains("let enabled = true;"));
+    assert!(rust.contains("let disabled = false;"));
+    assert!(rust.contains("let changed = enabled != disabled;"));
+}
+
 #[test]
 fn rust_lowering_maps_try_operator_to_rust_result_propagation() {
     let source = r#"