From 75c059bf655b333e95b555e371fafbbacef0bc7e Mon Sep 17 00:00:00 2001
From: KtorZ <matthias.benkort@gmail.com>
Date: Fri, 30 Aug 2024 18:24:35 +0200
Subject: [PATCH] Fix module constant usage warnings.

---
 crates/aiken-lang/src/tests/check.rs | 27 +++++++++++++++++++++++++++
 crates/aiken-lang/src/tipo/infer.rs  |  8 ++++++++
 2 files changed, 35 insertions(+)

diff --git a/crates/aiken-lang/src/tests/check.rs b/crates/aiken-lang/src/tests/check.rs
index 62d34708..c41f807e 100644
--- a/crates/aiken-lang/src/tests/check.rs
+++ b/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"
+    ));
+}
diff --git a/crates/aiken-lang/src/tipo/infer.rs b/crates/aiken-lang/src/tipo/infer.rs
index 7b469c6f..5aa2d40f 100644
--- a/crates/aiken-lang/src/tipo/infer.rs
+++ b/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?"),