fix: Display function name and body when inlining recursion limit hit

compiler/noirc_evaluator/src/ssa/opt/inlining.rs

@@ -291,13 +291,14 @@ impl InlineContext {
     ) -> Vec<ValueId> {
         self.recursion_level += 1;
 
+        let source_function = &ssa.functions[&id];
+
         if self.recursion_level > RECURSION_LIMIT {
             panic!(
-                "Attempted to recur more than {RECURSION_LIMIT} times during function inlining."
+                "Attempted to recur more than {RECURSION_LIMIT} times during inlining function '{}': {}", source_function.name(), source_function
             );
         }
 
-        let source_function = &ssa.functions[&id];
         let mut context = PerFunctionContext::new(self, source_function);
 
         let parameters = source_function.parameters();
@@ -967,4 +968,28 @@ mod test {
         let main = ssa.main();
         assert_eq!(main.reachable_blocks().len(), 4);
     }
+
+    #[test]
+    #[should_panic(
+        expected = "Attempted to recur more than 1000 times during inlining function 'main': acir(inline) fn main f0 {"
+    )]
+    fn unconditional_recursion() {
+        // fn main f1 {
+        //   b0():
+        //     call f1()
+        //     return
+        // }
+        let main_id = Id::test_new(0);
+        let mut builder = FunctionBuilder::new("main".into(), main_id);
+
+        let main = builder.import_function(main_id);
+        let results = builder.insert_call(main, Vec::new(), vec![]).to_vec();
+        builder.terminate_with_return(results);
+
+        let ssa = builder.finish();
+        assert_eq!(ssa.functions.len(), 1);
+
+        let inlined = ssa.inline_functions();
+        assert_eq!(inlined.functions.len(), 0);
+    }
 }

compiler/noirc_frontend/src/tests.rs

@@ -1974,7 +1974,7 @@
 }
 
 // TODO(https://github.com/noir-lang/noir/issues/6238):
 // The EvaluatedGlobalIsntU32 warning is a stopgap
 // (originally from https://github.com/noir-lang/noir/issues/6125)
 #[test]
 fn numeric_generic_field_larger_than_u32() {
@@ -1991,7 +1991,7 @@
     assert_eq!(errors.len(), 2);
     assert!(matches!(
         errors[0].0,
         CompilationError::TypeError(TypeCheckError::EvaluatedGlobalIsntU32 { .. }),
     ));
     assert!(matches!(
         errors[1].0,
@@ -2000,7 +2000,7 @@
 }
 
 // TODO(https://github.com/noir-lang/noir/issues/6238):
 // The EvaluatedGlobalIsntU32 warning is a stopgap
 // (originally from https://github.com/noir-lang/noir/issues/6126)
 #[test]
 fn numeric_generic_field_arithmetic_larger_than_u32() {
@@ -2029,7 +2029,7 @@
 
     assert!(matches!(
         errors[0].0,
         CompilationError::TypeError(TypeCheckError::EvaluatedGlobalIsntU32 { .. }),
     ));
 
     assert!(matches!(
@@ -2165,7 +2165,7 @@
     assert_eq!(errors.len(), 3);
 
     // TODO(https://github.com/noir-lang/noir/issues/6238):
     // The EvaluatedGlobalIsntU32 warning is a stopgap
     assert!(matches!(
         errors[0].0,
         CompilationError::TypeError(TypeCheckError::EvaluatedGlobalIsntU32 { .. }),
@@ -3185,7 +3185,7 @@
 }
 
 #[test]
 fn arithmetic_generics_canonicalization_deduplication_regression() {
     let source = r#"
         struct ArrData<let N: u32> {
             a: [Field; N],
@@ -3389,3 +3389,14 @@
     let errors = get_program_errors(src);
     assert_eq!(errors.len(), 1);
 }
+
+#[test]
+fn unconditional_recursion() {
+    let src = r#"
+    fn main() {
+        main()
+    }
+    "#;
+    // It would be nice if it issued a warning.
+    assert_no_errors(src);
+}