Mark pure function effects where necessary

src/analyzer/expr/call_analyzer.rs

@@ -2,7 +2,7 @@ use std::sync::Arc;
 
 use hakana_reflection_info::code_location::HPos;
 use hakana_reflection_info::issue::{Issue, IssueKind};
-use hakana_reflection_info::{GenericParent, EFFECT_IMPURE, EFFECT_WRITE_PROPS};
+use hakana_reflection_info::{GenericParent, EFFECT_IMPURE, EFFECT_PURE, EFFECT_WRITE_PROPS};
 use hakana_str::StrId;
 use hakana_type::template::standin_type_replacer::get_relevant_bounds;
 use hakana_type::type_comparator::type_comparison_result::TypeComparisonResult;
@@ -504,7 +504,10 @@ pub(crate) fn apply_effects(
             }
         }
         FnEffect::Pure => {
-            // do nothing, it's a pure function
+            analysis_data.expr_effects.insert(
+                (pos.start_offset() as u32, pos.end_offset() as u32),
+                EFFECT_PURE,
+            );
         }
         FnEffect::Unknown => {
             // yet to be computed

src/analyzer/stmt_analyzer.rs

@@ -345,6 +345,7 @@ fn detect_unused_statement_expressions(
             }
         }
     }
+
     if let Some(functionlike_id) = functionlike_id {
         if let FunctionLikeIdentifier::Function(function_id) = functionlike_id {
             let codebase = statements_analyzer.get_codebase();

tests/unused/UnusedCode/usedFunctionReferencedInClosure/output.txt

@@ -0,0 +1 @@
+ERROR: UnusedStatement - input.hack:6:5 - This statement has no effect and can be removed

tests/unused/UnusedExpression/unusedPureMethodCall/input.hack

@@ -0,0 +1,15 @@
+class UnusedMethodClass {
+    public function getId()[]: int {
+		return 5;
+	}
+
+	public function doWork(): string {
+		return '';
+	}
+}
+
+function foo(): void {
+    $c = new UnusedMethodClass();
+    $c->getId();
+    $c->doWork();
+}

tests/unused/UnusedExpression/unusedPureMethodCall/output.txt

@@ -0,0 +1 @@
+ERROR: UnusedStatement - input.hack:13:5 - This statement has no effect and can be removed