While looking at PR c/16351, I noticed that all tests proposed for
-Wnull-attribute
(https://gcc.gnu.org/ml/gcc-patches/2014-01/msg01715.html) could be
warned from the FEs by simply extending the existing Wnonnull.
Bootstrapped and regression tested on x86_64-linux-gnu.
OK?
gcc/ChangeLog:
2015-07-22 Manuel López-Ibáñez <m...@gcc.gnu.org>
PR c/16351
* doc/invoke.texi (Wnonnull): Document behavior for
returns_nonnull.
gcc/testsuite/ChangeLog:
2015-07-22 Manuel López-Ibáñez <m...@gcc.gnu.org>
PR c/16351
* c-c++-common/wnonnull-1.c: New test.
gcc/cp/ChangeLog:
2015-07-22 Manuel López-Ibáñez <m...@gcc.gnu.org>
PR c/16351
* typeck.c (check_return_expr): Call maybe_warn_returns_nonnull.
gcc/c-family/ChangeLog:
2015-07-22 Manuel López-Ibáñez <m...@gcc.gnu.org>
PR c/16351
* c-common.c (maybe_warn_returns_nonnull): New.
* c-common.h (maybe_warn_returns_nonnull): Declare.
gcc/c/ChangeLog:
2015-07-22 Manuel López-Ibáñez <m...@gcc.gnu.org>
PR c/16351
* c-typeck.c (c_finish_return): Call maybe_warn_returns_nonnull.
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 225868)
+++ gcc/doc/invoke.texi (working copy)
@@ -3709,11 +3709,13 @@ formats that may yield only a two-digit
@item -Wnonnull
@opindex Wnonnull
@opindex Wno-nonnull
Warn about passing a null pointer for arguments marked as
-requiring a non-null value by the @code{nonnull} function attribute.
+requiring a non-null value by the @code{nonnull} function attribute
+or returning a null pointer from a function declared with the attribute
+@code{returns_nonnull}.
@option{-Wnonnull} is included in @option{-Wall} and @option{-Wformat}. It
can be disabled with the @option{-Wno-nonnull} option.
@item -Winit-self @r{(C, C++, Objective-C and Objective-C++ only)}
Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c (revision 225868)
+++ gcc/c-family/c-common.c (working copy)
@@ -9508,10 +9508,22 @@ check_nonnull_arg (void * ARG_UNUSED (ct
if (integer_zerop (param))
warning (OPT_Wnonnull, "null argument where non-null required "
"(argument %lu)", (unsigned long) param_num);
}
+/* Possibly warn if RETVAL is a null pointer and FNDECL is declared
+ with attribute returns_nonnull. LOC is the location of RETVAL. */
+
+void
+maybe_warn_returns_nonnull (location_t loc, tree fndecl, tree retval)
+{
+ if (integer_zerop (retval)
+ && lookup_attribute ("returns_nonnull",
+ TYPE_ATTRIBUTES (TREE_TYPE (fndecl))))
+ warning_at (loc, OPT_Wnonnull, "null return value where non-null
required");
+}
+
/* Helper for nonnull attribute handling; fetch the operand number
from the attribute argument list. */
static bool
get_nonnull_operand (tree arg_num_expr, unsigned HOST_WIDE_INT *valp)
Index: gcc/c-family/c-common.h
===================================================================
--- gcc/c-family/c-common.h (revision 225868)
+++ gcc/c-family/c-common.h (working copy)
@@ -1049,10 +1049,11 @@ extern void do_warn_double_promotion (tr
extern void set_underlying_type (tree);
extern void record_types_used_by_current_var_decl (tree);
extern void record_locally_defined_typedef (tree);
extern void maybe_record_typedef_use (tree);
extern void maybe_warn_unused_local_typedefs (void);
+extern void maybe_warn_returns_nonnull (location_t, tree, tree);
extern void maybe_warn_bool_compare (location_t, enum tree_code, tree, tree);
extern vec<tree, va_gc> *make_tree_vector (void);
extern void release_tree_vector (vec<tree, va_gc> *);
extern vec<tree, va_gc> *make_tree_vector_single (tree);
extern vec<tree, va_gc> *make_tree_vector_from_list (tree);
Index: gcc/c/c-typeck.c
===================================================================
--- gcc/c/c-typeck.c (revision 225868)
+++ gcc/c/c-typeck.c (working copy)
@@ -9372,10 +9372,11 @@ c_finish_return (location_t loc, tree re
{
semantic_type = TREE_TYPE (retval);
retval = TREE_OPERAND (retval, 0);
}
retval = c_fully_fold (retval, false, NULL);
+ maybe_warn_returns_nonnull (loc, current_function_decl, retval);
if (semantic_type)
retval = build1 (EXCESS_PRECISION_EXPR, semantic_type, retval);
}
if (!retval)
Index: gcc/testsuite/c-c++-common/wnonnull-1.c
===================================================================
--- gcc/testsuite/c-c++-common/wnonnull-1.c (revision 0)
+++ gcc/testsuite/c-c++-common/wnonnull-1.c (revision 0)
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-options "-Wnonnull" } */
+
+
+extern void foo(void *) __attribute__ ((__nonnull__ (1)));
+
+int z;
+int y;
+
+void
+com (int a)
+{
+ foo (a == 42 ? &z : (void *) 0); /* { dg-warning "null" } */
+}
+
+void
+bar (void)
+{
+ foo ((void *)0); /* { dg-warning "null" } */
+}
+
+int * foo_r(int a) __attribute__((returns_nonnull));
+int * bar_r(void) __attribute__((returns_nonnull));
+
+int *
+foo_r(int a)
+{
+ switch (a)
+ {
+ case 0:
+ return &z;
+ default:
+ return (int *)0; /* { dg-warning "null" } */
+ }
+}
+
+int *
+bar_r (void)
+{
+ return 0; /* { dg-warning "null" } */
+}
+
Index: gcc/cp/typeck.c
===================================================================
--- gcc/cp/typeck.c (revision 225868)
+++ gcc/cp/typeck.c (working copy)
@@ -8702,10 +8702,12 @@ check_return_expr (tree retval, bool *no
/* We don't need to do any conversions when there's nothing being
returned. */
if (!retval)
return NULL_TREE;
+ maybe_warn_returns_nonnull (input_location, current_function_decl, retval);
+
/* Do any required conversions. */
if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
/* No conversions are required. */
;
else
