When initializing a nonstring char array when compiled with
-Wunterminated-string-initialization the warning trips even when
truncating the trailing NUL character from the string constant. Only
warn about this when running under -Wc++-compat since under C++ we should
not initialize nonstrings from C strings.
PR c/117178
gcc/c/ChangeLog:
* c-typeck.cc (digest_init): Check for nonstring attribute and
avoid warning when only the trailing NUL is truncated.
(build_c_cast): Update function call prototype.
(store_init_value): Ditto.
(output_init_element): Ditto.
gcc/testsuite/ChangeLog:
* gcc.dg/Wunterminated-string-initialization.c: Update for
new warning text and check for nonstring cases.
* gcc.dg/Wunterminated-string-initialization-c++.c: Duplicate
C test for -Wc++-compat.
---
gcc/c/c-typeck.cc | 73 ++++++++++++-------
.../Wunterminated-string-initialization-c++.c | 28 +++++++
.../Wunterminated-string-initialization.c | 26 ++++++-
3 files changed, 98 insertions(+), 29 deletions(-)
create mode 100644
gcc/testsuite/gcc.dg/Wunterminated-string-initialization-c++.c
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 10b02da8752d..5cd0c07b87b1 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -116,8 +116,8 @@ static void push_member_name (tree);
static int spelling_length (void);
static char *print_spelling (char *);
static void warning_init (location_t, int, const char *);
-static tree digest_init (location_t, tree, tree, tree, bool, bool, bool, bool,
- bool, bool);
+static tree digest_init (location_t, tree, tree, tree, tree, bool, bool, bool,
+ bool, bool, bool);
static void output_init_element (location_t, tree, tree, bool, tree, tree,
bool,
bool, struct obstack *);
static void output_pending_init_elements (int, struct obstack *);
@@ -6731,7 +6731,7 @@ build_c_cast (location_t loc, tree type, tree expr)
t = build_constructor_single (type, field, t);
if (!maybe_const)
t = c_wrap_maybe_const (t, true);
- t = digest_init (loc, type, t,
+ t = digest_init (loc, field, type, t,
NULL_TREE, false, false, false, true, false, false);
TREE_CONSTANT (t) = TREE_CONSTANT (value);
return t;
@@ -8646,8 +8646,8 @@ store_init_value (location_t init_loc, tree decl, tree
init, tree origtype)
}
bool constexpr_p = (VAR_P (decl)
&& C_DECL_DECLARED_CONSTEXPR (decl));
- value = digest_init (init_loc, type, init, origtype, npc, int_const_expr,
- arith_const_expr, true,
+ value = digest_init (init_loc, decl, type, init, origtype, npc,
+ int_const_expr, arith_const_expr, true,
TREE_STATIC (decl) || constexpr_p, constexpr_p);
/* Store the expression if valid; else report error. */
@@ -8996,8 +8996,8 @@ check_constexpr_init (location_t loc, tree type, tree
init,
on initializers for 'constexpr' objects apply. */
static tree
-digest_init (location_t init_loc, tree type, tree init, tree origtype,
- bool null_pointer_constant, bool int_const_expr,
+digest_init (location_t init_loc, tree field, tree type, tree init,
+ tree origtype, bool null_pointer_constant, bool int_const_expr,
bool arith_const_expr, bool strict_string,
bool require_constant, bool require_constexpr)
{
@@ -9132,27 +9132,46 @@ digest_init (location_t init_loc, tree type, tree init,
tree origtype,
&& TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
{
unsigned HOST_WIDE_INT len = TREE_STRING_LENGTH (inside_init);
- unsigned unit = TYPE_PRECISION (typ1) / BITS_PER_UNIT;
-
- /* Subtract the size of a single (possibly wide) character
- because it's ok to ignore the terminating null char
- that is counted in the length of the constant. */
- if (compare_tree_int (TYPE_SIZE_UNIT (type), len - unit) < 0)
- pedwarn_init (init_loc, 0,
- ("initializer-string for array of %qT "
- "is too long"), typ1);
- else if (warn_unterminated_string_initialization
- && compare_tree_int (TYPE_SIZE_UNIT (type), len) < 0)
- warning_at (init_loc, OPT_Wunterminated_string_initialization,
- ("initializer-string for array of %qT "
- "is too long"), typ1);
+
if (compare_tree_int (TYPE_SIZE_UNIT (type), len) < 0)
{
- unsigned HOST_WIDE_INT size
- = tree_to_uhwi (TYPE_SIZE_UNIT (type));
- const char *p = TREE_STRING_POINTER (inside_init);
-
- inside_init = build_string (size, p);
+ unsigned HOST_WIDE_INT avail
+ = tree_to_uhwi (TYPE_SIZE_UNIT (type));
+ unsigned unit = TYPE_PRECISION (typ1) / BITS_PER_UNIT;
+ const char *p = TREE_STRING_POINTER (inside_init);
+
+ /* Construct truncated string. */
+ inside_init = build_string (avail, p);
+
+ /* Subtract the size of a single (possibly wide) character
+ because it may be ok to ignore the terminating NUL char
+ that is counted in the length of the constant. */
+ if (warn_cxx_compat || len - unit > avail)
+ {
+ pedwarn_init (init_loc, 0,
+ ("initializer-string for array of %qT "
+ "is too long (%lu chars into %lu "
+ "available)"), typ1, len, avail);
+ }
+ else if (warn_unterminated_string_initialization)
+ {
+ if (len - unit > avail)
+ warning_at (init_loc,
+ OPT_Wunterminated_string_initialization,
+ ("initializer-string for array of %qT "
+ "is too long (%lu chars into %lu "
+ "available)"), typ1, len, avail);
+ else if (get_attr_nonstring_decl (field) == NULL_TREE)
+ {
+ warning_at (init_loc,
+ OPT_Wunterminated_string_initialization,
+ ("initializer-string for array of %qT "
+ "truncates NUL terminator but "
+ "destination lacks 'nonstring' attribute "
+ "(%lu chars into %lu available)"),
+ typ1, len, avail);
+ }
+ }
}
}
@@ -11173,7 +11192,7 @@ output_init_element (location_t loc, tree value, tree
origtype,
if (!require_constexpr_value
|| !npc
|| TREE_CODE (constructor_type) != POINTER_TYPE)
- new_value = digest_init (loc, type, new_value, origtype, npc,
+ new_value = digest_init (loc, field, type, new_value, origtype, npc,
int_const_expr, arith_const_expr, strict_string,
require_constant_value, require_constexpr_value);
if (new_value == error_mark_node)
diff --git a/gcc/testsuite/gcc.dg/Wunterminated-string-initialization-c++.c
b/gcc/testsuite/gcc.dg/Wunterminated-string-initialization-c++.c
new file mode 100644
index 000000000000..18e8054eb5d3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wunterminated-string-initialization-c++.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-Wc++-compat -Wunterminated-string-initialization" } */
+
+char a1[] = "a";
+char a2[1] = "a"; /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+char a2nonstring[1] __attribute__((nonstring)) = "a"; /* { dg-warning
"initializer-string for array of 'char' is too long" } */
+char a3[1] = "aa"; /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+char a4[2] = "a";
+
+struct has_str {
+ int a;
+ char str1[4];
+ char str2[4];
+ char str3[4];
+ char tag1[4] __attribute__((nonstring));
+ char tag2[4] __attribute__((nonstring));
+ char tag3[4] __attribute__((nonstring));
+ int b;
+};
+
+struct has_str foo = {
+ .str1 = "111",
+ .str2 = "2222", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+ .str3 = "33333", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+ .tag1 = "AAA",
+ .tag2 = "BBBB", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+ .tag3 = "CCCCC", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+};
diff --git a/gcc/testsuite/gcc.dg/Wunterminated-string-initialization.c
b/gcc/testsuite/gcc.dg/Wunterminated-string-initialization.c
index 13d5dbc66400..315e7d53e253 100644
--- a/gcc/testsuite/gcc.dg/Wunterminated-string-initialization.c
+++ b/gcc/testsuite/gcc.dg/Wunterminated-string-initialization.c
@@ -2,5 +2,27 @@
/* { dg-options "-Wunterminated-string-initialization" } */
char a1[] = "a";
-char a2[1] = "a"; /* { dg-warning "initializer-string for array of 'char'
is too long" } */
-char a3[2] = "a";
+char a2[1] = "a"; /* { dg-warning "initializer-string for array of 'char'
truncates" } */
+char a2nonstring[1] __attribute__((nonstring)) = "a";
+char a3[1] = "aa"; /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+char a4[2] = "a";
+
+struct has_str {
+ int a;
+ char str1[4];
+ char str2[4];
+ char str3[4];
+ char tag1[4] __attribute__((nonstring));
+ char tag2[4] __attribute__((nonstring));
+ char tag3[4] __attribute__((nonstring));
+ int b;
+};
+
+struct has_str foo = {
+ .str1 = "111",
+ .str2 = "2222", /* { dg-warning "initializer-string for array of 'char'
truncates" } */
+ .str3 = "33333", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+ .tag1 = "AAA",
+ .tag2 = "BBBB",
+ .tag3 = "CCCCC", /* { dg-warning "initializer-string for array of 'char'
is too long" } */
+};
--
2.34.1
