Fix module constant usage warnings.

crates/aiken-lang/src/tests/check.rs

@@ -3237,3 +3237,30 @@ fn extraneous_fallback_on_exhaustive_handlers() {
         Err((_, Error::UnexpectedValidatorFallback { .. }))
     ))
 }
+
+#[test]
+fn constant_usage() {
+    let source_code = r#"
+        pub const some_bool_constant: Bool = True
+
+        const some_int_constant: Int = 42
+
+        const some_string_constant: String = @"Aiken"
+
+        test foo() {
+          some_int_constant == 42
+        }
+    "#;
+
+    let result = check(parse(source_code));
+    assert!(result.is_ok());
+
+    let (warnings, _) = result.unwrap();
+    assert!(matches!(
+        &warnings[..],
+        [Warning::UnusedPrivateModuleConstant {
+            name,
+            ..
+        }] if name == "some_string_constant"
+    ));
+}

crates/aiken-lang/src/tipo/infer.rs

@@ -632,6 +632,14 @@ fn infer_definition(
                 location,
             )?;
 
+            // NOTE: The assignment above is only a convenient way to create the TypedExpression
+            // that will be reduced at compile-time. We must increment its usage to not
+            // automatically trigger a warning since we are virtually creating a block with a
+            // single assignment that is then left unused.
+            //
+            // The usage of the constant is tracked through different means.
+            environment.increment_usage(&name);
+
             let typed_expr = match typed_assignment {
                 TypedExpr::Assignment { value, .. } => value,
                 _ => unreachable!("infer_assignment inferred something else than an assignment?"),