[PATCH] system: Add WARN_UNUSED_RESULT

Marek Polacek polacek@redhat.com
Thu Nov 12 03:03:48 GMT 2020


I'd like to have the option of marking functions with
__attribute__ ((__warn_unused_result__)), so this patch adds a macro.
And use it for maybe_wrap_with_location, it's always a bug if the
return value is not used, which happened to me and got me confused.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

gcc/ChangeLog:

	* system.h (WARN_UNUSED_RESULT): Define for GCC >= 3.4.
	* tree.h (maybe_wrap_with_location): Add WARN_UNUSED_RESULT.
---
 gcc/system.h | 6 ++++++
 gcc/tree.h   | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/gcc/system.h b/gcc/system.h
index b0f3f1dd019..6f6ab616a61 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -789,6 +789,12 @@ extern void fancy_abort (const char *, int, const char *)
 #define ALWAYS_INLINE inline
 #endif
 
+#if GCC_VERSION >= 3004
+#define WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
+#else
+#define WARN_UNUSED_RESULT
+#endif
+
 /* Use gcc_unreachable() to mark unreachable locations (like an
    unreachable default case of a switch.  Do not use gcc_assert(0).  */
 #if (GCC_VERSION >= 4005) && !ENABLE_ASSERT_CHECKING
diff --git a/gcc/tree.h b/gcc/tree.h
index 684be10b440..9a713cdb0c7 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1214,7 +1214,7 @@ get_expr_source_range (tree expr)
 extern void protected_set_expr_location (tree, location_t);
 extern void protected_set_expr_location_if_unset (tree, location_t);
 
-extern tree maybe_wrap_with_location (tree, location_t);
+WARN_UNUSED_RESULT extern tree maybe_wrap_with_location (tree, location_t);
 
 extern int suppress_location_wrappers;
 

base-commit: 0f5f9ed5e5a041b636cc002451b1e8b2295f8e4f
-- 
2.28.0



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