On 10/17/16 20:05, Joseph Myers wrote:
> On Sun, 16 Oct 2016, Bernd Edlinger wrote:
>
>> Second, the declaration in the glibc header files simply look wrong,
>> because the type of argv, and envp is "char *const *" while the
>> builtin function wants "const char**", thus only the array of char*
>> itself is const, not the actual char stings they point to.
>
> char *const * is the POSIX type. (It can't be const char ** or const char
> *const * because you can't convert char ** implicitly to those types in
> ISO C.) You'd need to check the list archives for rationale for the
> built-in functions doing something different.
>
Yes, that was discussed here:
https://gcc.gnu.org/ml/gcc-patches/2004-03/msg01148.html
No mention why the BT_PTR_CONST_TYPE does not match the posix type.
But the right types were used on __gcov_execv/e/p stubs, so the author
did know the right types at least.
So I think that was broken from the beginning, but that was hidden by
the loose checking in the C FE and not warning in the C++ FE when
prototypes don't match.
>> Third, in C the builtins are not diagnosed, because C does only look
>> at the mode of the parameters see match_builtin_function_types in
>> c/c-decl.c, which may itself be wrong, because that makes an ABI
>> decision dependent on the mode of the parameter.
>
> The matching needs to be loose because of functions using types such as
> FILE * where the compiler doesn't know the exact contents of the type when
> processing built-in function definitions. (Historically there were also
> issues with pre-ISO headers, but that may be less relevant now.)
>
The C++ FE has exactly the same problem with FILE* and struct tm*
but it solves it differently and "learns" the type but only for FILE*
and with this patch also for const struct tm*. It is a lot more
restrictive than C, but that is because of the ++ ;)
Well in that case the posix functions have to use the prototypes
from POSIX.1.2008 although their rationale is a bit silly...
This updated patch fixes the prototype of execv/p/e,
and adds a new test case that checks that no type conflict
exists in the execve built-in any more.
Now we have no -Wsystem-headers warnings with glibc-headers any more.
And the gcov builtin also is working with C++.
Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?
Thanks
Bernd.
gcc:
2016-10-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR c++/71973
* doc/invoke.texi: Document -Wbuiltin-function-redefined.
* builtin-types.def (BT_CONST_TM_PTR): New primitive type.
(BT_PTR_CONST_STRING): Updated.
(BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_PTR): Removed.
(BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_TM_PTR): New function type.
* builtins.def (strftime): Update builtin function.
* tree-core.h (TI_CONST_TM_PTR_TYPE): New enum value.
* tree.h (const_tm_ptr_type_node): New type node.
* tree.c (free_lang_data, build_common_tree_nodes): Initialize
const_tm_ptr_type_node.
c-family:
2016-10-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR c++/71973
* c.opt (Wbuiltin-function-redefined): New warning.
* c-common.c (c_common_nodes_and_builtins): Initialize
const_tm_ptr_type_node.
cp:
2016-10-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR c++/71973
* decl.c (duplicate_decls): Warn when a built-in function is redefined.
Don't overload builtin functions with C++ functions.
Handle const_tm_ptr_type_node like file_ptr_node.
Copy the TREE_NOTHROW flag unmodified to the old decl.
lto:
2016-10-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR c++/71973
* lto-lang.c (lto_init): Assert const_tm_ptr_type_node is sane.
testsuite:
2016-10-17 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR c++/71973
* g++.dg/pr71973-1.C: New test.
* g++.dg/pr71973-2.C: New test.
* g++.dg/pr71973-3.C: New test.
* g++.dg/lookup/extern-c-redecl4.C: Adjust test expectations.
Index: gcc/builtin-types.def
===================================================================
--- gcc/builtin-types.def (revision 241271)
+++ gcc/builtin-types.def (working copy)
@@ -103,6 +103,7 @@ DEF_PRIMITIVE_TYPE (BT_COMPLEX_LONGDOUBLE, complex
DEF_PRIMITIVE_TYPE (BT_PTR, ptr_type_node)
DEF_PRIMITIVE_TYPE (BT_FILEPTR, fileptr_type_node)
+DEF_PRIMITIVE_TYPE (BT_CONST_TM_PTR, const_tm_ptr_type_node)
DEF_PRIMITIVE_TYPE (BT_CONST_PTR, const_ptr_type_node)
DEF_PRIMITIVE_TYPE (BT_VOLATILE_PTR,
build_pointer_type
@@ -146,7 +147,12 @@ DEF_PRIMITIVE_TYPE (BT_I16, builtin_type_for_size
DEF_PRIMITIVE_TYPE (BT_BND, pointer_bounds_type_node)
-DEF_POINTER_TYPE (BT_PTR_CONST_STRING, BT_CONST_STRING)
+/* The C type `char * const *'. */
+DEF_PRIMITIVE_TYPE (BT_PTR_CONST_STRING,
+ build_pointer_type
+ (build_qualified_type (string_type_node,
+ TYPE_QUAL_CONST)))
+
DEF_POINTER_TYPE (BT_PTR_UINT, BT_UINT)
DEF_POINTER_TYPE (BT_PTR_LONG, BT_LONG)
DEF_POINTER_TYPE (BT_PTR_ULONG, BT_ULONG)
@@ -511,8 +517,8 @@ DEF_FUNCTION_TYPE_4 (BT_FN_SIZE_CONST_PTR_SIZE_SIZ
BT_SIZE, BT_CONST_PTR, BT_SIZE, BT_SIZE, BT_FILEPTR)
DEF_FUNCTION_TYPE_4 (BT_FN_INT_STRING_SIZE_CONST_STRING_VALIST_ARG,
BT_INT, BT_STRING, BT_SIZE, BT_CONST_STRING, BT_VALIST_ARG)
-DEF_FUNCTION_TYPE_4 (BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_PTR,
- BT_SIZE, BT_STRING, BT_SIZE, BT_CONST_STRING, BT_CONST_PTR)
+DEF_FUNCTION_TYPE_4 (BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_TM_PTR,
+ BT_SIZE, BT_STRING, BT_SIZE, BT_CONST_STRING, BT_CONST_TM_PTR)
DEF_FUNCTION_TYPE_4 (BT_FN_PTR_PTR_CONST_PTR_SIZE_SIZE,
BT_PTR, BT_PTR, BT_CONST_PTR, BT_SIZE, BT_SIZE)
DEF_FUNCTION_TYPE_4 (BT_FN_PTR_PTR_INT_SIZE_SIZE,
Index: gcc/builtins.def
===================================================================
--- gcc/builtins.def (revision 241271)
+++ gcc/builtins.def (working copy)
@@ -866,7 +866,7 @@ DEF_GCC_BUILTIN (BUILT_IN_RETURN_ADDRESS, "
DEF_GCC_BUILTIN (BUILT_IN_SAVEREGS, "saveregs", BT_FN_PTR_VAR, ATTR_NULL)
DEF_GCC_BUILTIN (BUILT_IN_SETJMP, "setjmp", BT_FN_INT_PTR, ATTR_RT_NOTHROW_LEAF_LIST)
DEF_EXT_LIB_BUILTIN (BUILT_IN_STRFMON, "strfmon", BT_FN_SSIZE_STRING_SIZE_CONST_STRING_VAR, ATTR_FORMAT_STRFMON_NOTHROW_3_4)
-DEF_LIB_BUILTIN (BUILT_IN_STRFTIME, "strftime", BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_PTR, ATTR_FORMAT_STRFTIME_NOTHROW_3_0)
+DEF_LIB_BUILTIN (BUILT_IN_STRFTIME, "strftime", BT_FN_SIZE_STRING_SIZE_CONST_STRING_CONST_TM_PTR, ATTR_FORMAT_STRFTIME_NOTHROW_3_0)
DEF_GCC_BUILTIN (BUILT_IN_TRAP, "trap", BT_FN_VOID, ATTR_NORETURN_NOTHROW_LEAF_LIST)
DEF_GCC_BUILTIN (BUILT_IN_UNREACHABLE, "unreachable", BT_FN_VOID, ATTR_CONST_NORETURN_NOTHROW_LEAF_LIST)
DEF_GCC_BUILTIN (BUILT_IN_UNWIND_INIT, "unwind_init", BT_FN_VOID, ATTR_NULL)
Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c (revision 241271)
+++ gcc/c-family/c-common.c (working copy)
@@ -4278,9 +4278,13 @@ c_common_nodes_and_builtins (void)
}
if (c_dialect_cxx ())
- /* For C++, make fileptr_type_node a distinct void * type until
- FILE type is defined. */
- fileptr_type_node = build_variant_type_copy (ptr_type_node);
+ {
+ /* For C++, make fileptr_type_node a distinct void * type until
+ FILE type is defined. */
+ fileptr_type_node = build_variant_type_copy (ptr_type_node);
+ /* Likewise for const struct tm*. */
+ const_tm_ptr_type_node = build_variant_type_copy (const_ptr_type_node);
+ }
record_builtin_type (RID_VOID, NULL, void_type_node);
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt (revision 241271)
+++ gcc/c-family/c.opt (working copy)
@@ -323,6 +323,10 @@ Wframe-address
C ObjC C++ ObjC++ Var(warn_frame_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
Warn when __builtin_frame_address or __builtin_return_address is used unsafely.
+Wbuiltin-function-redefined
+C++ ObjC++ Var(warn_builtin_function_redefined) Warning LangEnabledBy(C++ ObjC++,Wall)
+Warn when a built-in function is redefined.
+
Wbuiltin-macro-redefined
C ObjC C++ ObjC++ CPP(warn_builtin_macro_redefined) CppReason(CPP_W_BUILTIN_MACRO_REDEFINED) Var(cpp_warn_builtin_macro_redefined) Init(1) Warning
Warn when a built-in preprocessor macro is undefined or redefined.
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c (revision 241271)
+++ gcc/cp/decl.c (working copy)
@@ -1489,10 +1489,15 @@ duplicate_decls (tree newdecl, tree olddecl, bool
explicitly declared. */
if (DECL_ANTICIPATED (olddecl))
{
- /* Deal with fileptr_type_node. FILE type is not known
- at the time we create the builtins. */
tree t1, t2;
+ /* A new declaration doesn't match a built-in one unless it
+ is also extern "C". */
+ gcc_assert (DECL_IS_BUILTIN (olddecl));
+ gcc_assert (DECL_EXTERN_C_P (olddecl));
+ if (!DECL_EXTERN_C_P (newdecl))
+ return NULL_TREE;
+
for (t1 = TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
t2 = TYPE_ARG_TYPES (TREE_TYPE (olddecl));
t1 || t2;
@@ -1499,6 +1504,8 @@ duplicate_decls (tree newdecl, tree olddecl, bool
t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
if (!t1 || !t2)
break;
+ /* Deal with fileptr_type_node. FILE type is not known
+ at the time we create the builtins. */
else if (TREE_VALUE (t2) == fileptr_type_node)
{
tree t = TREE_VALUE (t1);
@@ -1519,8 +1526,34 @@ duplicate_decls (tree newdecl, tree olddecl, bool
TYPE_ARG_TYPES (TREE_TYPE (olddecl)) = oldargs;
}
}
+ /* Likewise for const struct tm*. */
+ else if (TREE_VALUE (t2) == const_tm_ptr_type_node)
+ {
+ tree t = TREE_VALUE (t1);
+
+ if (TYPE_PTR_P (t)
+ && TYPE_IDENTIFIER (TREE_TYPE (t))
+ == get_identifier ("tm")
+ && compparms (TREE_CHAIN (t1), TREE_CHAIN (t2)))
+ {
+ tree oldargs = TYPE_ARG_TYPES (TREE_TYPE (olddecl));
+
+ TYPE_ARG_TYPES (TREE_TYPE (olddecl))
+ = TYPE_ARG_TYPES (TREE_TYPE (newdecl));
+ types_match = decls_match (newdecl, olddecl);
+ if (types_match)
+ return duplicate_decls (newdecl, olddecl,
+ newdecl_is_friend);
+ TYPE_ARG_TYPES (TREE_TYPE (olddecl)) = oldargs;
+ }
+ }
else if (! same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
break;
+
+ warning_at (DECL_SOURCE_LOCATION (newdecl),
+ OPT_Wbuiltin_function_redefined,
+ "declaration of %q+#D conflicts with built-in "
+ "declaration %q#D", newdecl, olddecl);
}
else if ((DECL_EXTERN_C_P (newdecl)
&& DECL_EXTERN_C_P (olddecl))
@@ -1574,7 +1607,7 @@ duplicate_decls (tree newdecl, tree olddecl, bool
/* Whether or not the builtin can throw exceptions has no
bearing on this declarator. */
- TREE_NOTHROW (olddecl) = 0;
+ TREE_NOTHROW (olddecl) = TREE_NOTHROW (newdecl);
if (DECL_THIS_STATIC (newdecl) && !DECL_THIS_STATIC (olddecl))
{
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 241271)
+++ gcc/doc/invoke.texi (working copy)
@@ -256,7 +256,7 @@ Objective-C and Objective-C++ Dialects}.
-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return @gol
-Wno-aggressive-loop-optimizations -Warray-bounds -Warray-bounds=@var{n} @gol
--Wno-attributes -Wbool-compare -Wbool-operation @gol
+-Wno-attributes -Wbool-compare -Wbool-operation -Wbuiltin-function-redefined @gol
-Wno-builtin-macro-redefined -Wc90-c99-compat -Wc99-c11-compat @gol
-Wc++-compat -Wc++11-compat -Wc++14-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment -Wconditionally-supported @gol
@@ -3673,6 +3673,7 @@ Options} and @ref{Objective-C and Objective-C++ Di
-Warray-bounds=1 @r{(only with} @option{-O2}@r{)} @gol
-Wbool-compare @gol
-Wbool-operation @gol
+-Wbuiltin-function-redefined @r{(C++ and Objective-C++ only)} @gol
-Wc++11-compat -Wc++14-compat@gol
-Wchar-subscripts @gol
-Wcomment @gol
@@ -5793,6 +5794,13 @@ unrecognized attributes, function attributes appli
etc. This does not stop errors for incorrect use of supported
attributes.
+@item -Wbuiltin-function-redefined @r{(C++ and Objective-C++ only)}
+@opindex Wbuiltin-function-redefined
+@opindex Wno-builtin-function-redefined
+Do warn if built-in functions are redefined. This option is only
+supported for C++ and Objective-C++. It is implied by @option{-Wall},
+which can be disabled with @option{-Wno-builtin-function-redefined}.
+
@item -Wno-builtin-macro-redefined
@opindex Wno-builtin-macro-redefined
@opindex Wbuiltin-macro-redefined
Index: gcc/lto/lto-lang.c
===================================================================
--- gcc/lto/lto-lang.c (revision 241271)
+++ gcc/lto/lto-lang.c (working copy)
@@ -1266,6 +1266,10 @@ lto_init (void)
always use the C definition here in lto1. */
gcc_assert (fileptr_type_node == ptr_type_node);
gcc_assert (TYPE_MAIN_VARIANT (fileptr_type_node) == ptr_type_node);
+ /* Likewise for const struct tm*. */
+ gcc_assert (const_tm_ptr_type_node == const_ptr_type_node);
+ gcc_assert (TYPE_MAIN_VARIANT (const_tm_ptr_type_node)
+ == const_ptr_type_node);
ptrdiff_type_node = integer_type_node;
Index: gcc/testsuite/g++.dg/lookup/extern-c-redecl4.C
===================================================================
--- gcc/testsuite/g++.dg/lookup/extern-c-redecl4.C (revision 241271)
+++ gcc/testsuite/g++.dg/lookup/extern-c-redecl4.C (working copy)
@@ -3,7 +3,6 @@
// { dg-options "" }
// { dg-do compile }
-// { dg-final { scan-assembler "call\[\t \]+\[^\$\]*?_Z4forkv" { target i?86-*-* x86_64-*-* } } }
class frok
{
@@ -14,5 +13,5 @@ class frok
void
foo ()
{
- fork ();
+ fork (); // { dg-error "was not declared in this scope" }
}
Index: gcc/testsuite/g++.dg/pr71973-1.C
===================================================================
--- gcc/testsuite/g++.dg/pr71973-1.C (revision 0)
+++ gcc/testsuite/g++.dg/pr71973-1.C (working copy)
@@ -0,0 +1,14 @@
+// { dg-do compile }
+// { dg-options "-Wall -fdump-tree-eh" }
+
+extern "C"
+void fork () // { dg-warning "conflicts with built-in declaration" }
+__attribute__ ((__nothrow__));
+
+void foo () throw ()
+{
+ fork ();
+}
+
+// { dg-final { scan-tree-dump-not "eh_dispatch" "eh" } }
+// { dg-final { scan-tree-dump-not "resx" "eh" } }
Index: gcc/testsuite/g++.dg/pr71973-2.C
===================================================================
--- gcc/testsuite/g++.dg/pr71973-2.C (revision 0)
+++ gcc/testsuite/g++.dg/pr71973-2.C (working copy)
@@ -0,0 +1,18 @@
+// { dg-do compile }
+// { dg-options "-Wall -fdump-tree-eh" }
+
+typedef __SIZE_TYPE__ size_t;
+struct tm;
+
+extern "C"
+size_t strftime (char*, size_t, const char*, const struct tm*)
+__attribute__ ((__nothrow__));
+
+void foo () throw ()
+{
+ strftime (0,0,0,0); // { dg-warning "null argument where non-null required" }
+ // { dg-warning "too many arguments for format" "" { target *-*-* } .-1 }
+}
+
+// { dg-final { scan-tree-dump-not "eh_dispatch" "eh" } }
+// { dg-final { scan-tree-dump-not "resx" "eh" } }
Index: gcc/testsuite/g++.dg/pr71973-3.C
===================================================================
--- gcc/testsuite/g++.dg/pr71973-3.C (revision 0)
+++ gcc/testsuite/g++.dg/pr71973-3.C (working copy)
@@ -0,0 +1,14 @@
+// { dg-do compile }
+// { dg-options "-Wall -fdump-tree-eh" }
+
+extern "C"
+int execve (const char *__path, char *const __argv[], char *const __envp[])
+__attribute__ ((__nothrow__));
+
+void foo () throw ()
+{
+ execve (0,0,0);
+}
+
+// { dg-final { scan-tree-dump-not "eh_dispatch" "eh" } }
+// { dg-final { scan-tree-dump-not "resx" "eh" } }
Index: gcc/tree-core.h
===================================================================
--- gcc/tree-core.h (revision 241271)
+++ gcc/tree-core.h (working copy)
@@ -615,6 +615,7 @@ enum tree_index {
TI_VA_LIST_FPR_COUNTER_FIELD,
TI_BOOLEAN_TYPE,
TI_FILEPTR_TYPE,
+ TI_CONST_TM_PTR_TYPE,
TI_POINTER_SIZED_TYPE,
TI_POINTER_BOUNDS_TYPE,
Index: gcc/tree.c
===================================================================
--- gcc/tree.c (revision 241271)
+++ gcc/tree.c (working copy)
@@ -6006,6 +6006,7 @@ free_lang_data (void)
/* Create gimple variants for common types. */
ptrdiff_type_node = integer_type_node;
fileptr_type_node = ptr_type_node;
+ const_tm_ptr_type_node = const_ptr_type_node;
/* Reset some langhooks. Do not reset types_compatible_p, it may
still be used indirectly via the get_alias_set langhook. */
@@ -10310,6 +10311,7 @@ build_common_tree_nodes (bool signed_char)
const_ptr_type_node
= build_pointer_type (build_type_variant (void_type_node, 1, 0));
fileptr_type_node = ptr_type_node;
+ const_tm_ptr_type_node = const_ptr_type_node;
pointer_sized_int_node = build_nonstandard_integer_type (POINTER_SIZE, 1);
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 241271)
+++ gcc/tree.h (working copy)
@@ -3667,6 +3667,8 @@ tree_operand_check_code (const_tree __t, enum tree
#define va_list_fpr_counter_field global_trees[TI_VA_LIST_FPR_COUNTER_FIELD]
/* The C type `FILE *'. */
#define fileptr_type_node global_trees[TI_FILEPTR_TYPE]
+/* The C type `const struct tm *'. */
+#define const_tm_ptr_type_node global_trees[TI_CONST_TM_PTR_TYPE]
#define pointer_sized_int_node global_trees[TI_POINTER_SIZED_TYPE]
#define boolean_type_node global_trees[TI_BOOLEAN_TYPE]
