# S5267: Functions with noreturn attribute should not return
id: noreturn-returns
name: noreturn Functions Should Not Return
severity: error
category: reliability
defect_class: correctness
inline_tier: blocking
language: c

message: "function declared with noreturn attribute contains a return statement"

description: |
  A function marked with __attribute__((noreturn)) or _Noreturn promises
  to never return to its caller. A return statement inside it violates
  that contract and is undefined behavior.

  ✅ FIX: Use exit(), abort(), or longjmp() to terminate

  ```c
  __attribute__((noreturn)) void fatal(const char* msg) {
      fprintf(stderr, "%s\n", msg);
      abort();  // GOOD - never returns
  }
  ```

query: |
  (function_definition
    (attribute_specifier
      (argument_list
        (identifier) @ATTR))
    (compound_statement
      (return_statement) @RET)) @FUNC

metavars:
  - ATTR
  - RET
  - FUNC

post_filter: c_noreturn_attr

tags:
  - reliability
  - c
  - undefined-behavior
  - confusing

examples:
  bad: |
    __attribute__((noreturn)) void die() {
        printf("error\n");
        return;  // BAD - contradicts noreturn
    }

  good: |
    __attribute__((noreturn)) void die() {
        printf("error\n");
        abort();  // GOOD - never returns
    }

has_fix: false