[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 Marek Polacek changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #18 from Marek Polacek --- Fixed.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
--- Comment #17 from CVS Commits ---
The releases/gcc-11 branch has been updated by Marek Polacek
:
https://gcc.gnu.org/g:0fa9022aa30b9c4dde965a0406943c8c0af5eb54
commit r11-9715-g0fa9022aa30b9c4dde965a0406943c8c0af5eb54
Author: Marek Polacek
Date: Tue Mar 22 14:37:02 2022 -0400
c: -Wmissing-field-initializers and designated inits [PR82283, PR84685]
This patch fixes two kinds of wrong -Wmissing-field-initializers
warnings. Our docs say that this warning "does not warn about designated
initializers", but we give a warning for
1) the array case:
struct S {
struct N {
int a;
int b;
} c[1];
} d = {
.c[0].a = 1,
.c[0].b = 1, // missing initializer for field 'b' of 'struct N'
};
we warn because push_init_level, when constructing an array, clears
constructor_designated (which the warning relies on), and we forget
that we were in a designated initializer context. Fixed by the
push_init_level hunk; and
2) the compound literal case:
struct T {
int a;
int *b;
int c;
};
struct T t = { .b = (int[]){1} }; // missing initializer for field 'c' of
'struct T'
where set_designator properly sets constructor_designated to 1, but the
compound literal causes us to create a whole new initializer_stack in
start_init, which clears constructor_designated. Then, after we've parsed
the compound literal, finish_init flushes the initializer_stack entry,
but doesn't restore constructor_designated, so we forget we were in
a designated initializer context, which causes the bogus warning. (The
designated flag is also tracked in constructor_stack, but in this case,
we didn't perform push_init_level between set_designator and start_init
so it wasn't saved anywhere.)
PR c/82283
PR c/84685
gcc/c/ChangeLog:
* c-typeck.c (struct initializer_stack): Add 'designated' member.
(start_init): Set it.
(finish_init): Restore constructor_designated.
(push_init_level): Set constructor_designated to the value of
constructor_designated in the upper constructor_stack.
gcc/testsuite/ChangeLog:
* gcc.dg/Wmissing-field-initializers-1.c: New test.
* gcc.dg/Wmissing-field-initializers-2.c: New test.
* gcc.dg/Wmissing-field-initializers-3.c: New test.
* gcc.dg/Wmissing-field-initializers-4.c: New test.
* gcc.dg/Wmissing-field-initializers-5.c: New test.
(cherry picked from commit 4b7d9f8f51bd96d290aac230c71e501fcb6b21a6)
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 --- Comment #16 from Yann Droneaud --- (In reply to Marek Polacek from comment #13) > I have a patch which fixes all the testcases here. I've checked my test cases using godbolt gcc trunk, and, yeah, thanks a lot !
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 --- Comment #15 from Marek Polacek --- Patch seems safe to backport to 11.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
--- Comment #14 from CVS Commits ---
The trunk branch has been updated by Marek Polacek :
https://gcc.gnu.org/g:4b7d9f8f51bd96d290aac230c71e501fcb6b21a6
commit r12-7772-g4b7d9f8f51bd96d290aac230c71e501fcb6b21a6
Author: Marek Polacek
Date: Tue Mar 22 14:37:02 2022 -0400
c: -Wmissing-field-initializers and designated inits [PR82283, PR84685]
This patch fixes two kinds of wrong -Wmissing-field-initializers
warnings. Our docs say that this warning "does not warn about designated
initializers", but we give a warning for
1) the array case:
struct S {
struct N {
int a;
int b;
} c[1];
} d = {
.c[0].a = 1,
.c[0].b = 1, // missing initializer for field 'b' of 'struct N'
};
we warn because push_init_level, when constructing an array, clears
constructor_designated (which the warning relies on), and we forget
that we were in a designated initializer context. Fixed by the
push_init_level hunk; and
2) the compound literal case:
struct T {
int a;
int *b;
int c;
};
struct T t = { .b = (int[]){1} }; // missing initializer for field 'c' of
'struct T'
where set_designator properly sets constructor_designated to 1, but the
compound literal causes us to create a whole new initializer_stack in
start_init, which clears constructor_designated. Then, after we've parsed
the compound literal, finish_init flushes the initializer_stack entry,
but doesn't restore constructor_designated, so we forget we were in
a designated initializer context, which causes the bogus warning. (The
designated flag is also tracked in constructor_stack, but in this case,
we didn't perform push_init_level between set_designator and start_init
so it wasn't saved anywhere.)
PR c/82283
PR c/84685
gcc/c/ChangeLog:
* c-typeck.cc (struct initializer_stack): Add 'designated' member.
(start_init): Set it.
(finish_init): Restore constructor_designated.
(push_init_level): Set constructor_designated to the value of
constructor_designated in the upper constructor_stack.
gcc/testsuite/ChangeLog:
* gcc.dg/Wmissing-field-initializers-1.c: New test.
* gcc.dg/Wmissing-field-initializers-2.c: New test.
* gcc.dg/Wmissing-field-initializers-3.c: New test.
* gcc.dg/Wmissing-field-initializers-4.c: New test.
* gcc.dg/Wmissing-field-initializers-5.c: New test.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 Marek Polacek changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org Status|NEW |ASSIGNED --- Comment #13 from Marek Polacek --- I have a patch which fixes all the testcases here.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
rsandifo at gcc dot gnu.org changed:
What|Removed |Added
CC||rsandifo at gcc dot gnu.org
--- Comment #12 from rsandifo at gcc dot gnu.org
---
Here's another example, from Alexey Neyman
[https://gcc.gnu.org/pipermail/gcc-help/2022-February/141197.html]:
struct foo {
const char *a1;
const char * const *a2;
void *a3;
void *a4;
};
const char *aux[] = { "y", 0 };
struct foo a = {
.a1 = "x",
#if defined(CASE1)
.a2 = (const char * const []){ "y", 0 },
#elif defined(CASE2)
.a2 = aux,
#elif defined(CASE3)
.a2 = 0,
#elif defined(CASE4)
/* .a2 not initialized */
#elif defined(CASE5)
.a2 = (const char * const []){ "y", 0 },
.a3 = 0,
#endif
};
struct foo b = {
.a2 = (const char * const []){ "y", 0 },
.a1 = "x",
};
Only CASE1 of a warns; the others are (correctly) accepted
without warnings.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 --- Comment #11 from Jonathan Wakely --- (In reply to Robert Dumitru from comment #10) > I think https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99081 is also relating > to this. A similar issue, but I think the code for parsing these initializes in C and C++ is completely separate. I've added it to the "See Also" field anyway.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
Robert Dumitru changed:
What|Removed |Added
CC||robert.dumitru@cyberthorstu
||dios.com
--- Comment #10 from Robert Dumitru ---
We are experiencing the same issue:
The warning: missing initializer for field ... [-Wmissing-field-initializers]
is being thrown incorrectly.
The following code is correct, however [-Wmissing-field-initializers] are
shown.
struct test_t{
int value1;
int value2;
};
struct test_t test[] = {
[0].value1 = 1,
[0].value2 = 2,
[1].value1 = 10,
[1].value2 = 20
};
int main(){
return 0;
}
warning: missing initializer for field 'value2' of 'struct test_t'
[-Wmissing-field-initializers]
[0].value2 = 2,
warning: missing initializer for field 'value2' of 'struct test_t'
[-Wmissing-field-initializers]
[1].value2 = 20
The initialization is correct:
_test:
.long 1
.long 2
.long 10
.long 20
This bug was discovered first on version 8.3 but it can be reproduced on
version 10.2 as well. Please note you need the -Wextra flag in order to
reproduce this.
I think https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99081 is also relating to
this.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 Martin Liška changed: What|Removed |Added CC||marxin at gcc dot gnu.org, ||mpolacek at gcc dot gnu.org --- Comment #9 from Martin Liška --- @Marek: Would it be possible to fix these issues in C FE?
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 --- Comment #8 from Yann Droneaud --- See also this stack overflow question https://stackoverflow.com/questions/49081541/compound-literal-and-designated-initializer-warning-from-gcc-but-not-clang
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 --- Comment #7 from Yann Droneaud --- See also bug #84685 which is a very likely duplicate of this one.
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
--- Comment #6 from Yann Droneaud ---
Found this one on stack overflow[1], and I find it a bit embarrassing:
struct {
struct {
int a;
int b;
} c[1];
} d = {
.c[0].a = 1,
.c[0].b = 1,
};
Results in the following warning:
:7:8: error: missing initializer for field 'b' of 'struct
' [-Werror=missing-field-initializers]
7 |.c[0].b = 1,
|^
:4:9: note: 'b' declared here
4 | int b;
| ^
cc1: all warnings being treated as errors
Compiler returned: 1
See https://godbolt.org/z/zGqM7C
GCC emits a warning about a field missing an initializer despite being
obviously explicitly initialized.
If the present but missing initialization is removed:
struct {
struct {
int a;
int b;
} c[1];
} d = {
.c[0].a = 1,
};
GCC complains, incorrectly, about a missing initializer, as described in
previous comments:
:8:1: error: missing initializer for field 'b' of 'struct
' [-Werror=missing-field-initializers]
8 | };
| ^
:4:9: note: 'b' declared here
4 | int b;
| ^
cc1: all warnings being treated as errors
Compiler returned: 1
See https://godbolt.org/z/8NRwo5
[1]
https://stackoverflow.com/questions/22194935/wmissing-field-initializer-when-using-designated-initializers
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
--- Comment #5 from Yann Droneaud ---
For a full combo, here's the almost original code that trigger the two errors
above with GLibc < 2.28, only one with newer Glibc.
#define _GNU_SOURCE 1
#include
#include
#include
int test(int fd)
{
static const char message[] = "Hello world";
struct sockaddr_in addr = {
.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
.sin_port = htons(12345),
};
struct iovec vec = {
.iov_base = (void *)message,
.iov_len = sizeof(message),
};
struct mmsghdr mmsghdr = {
.msg_hdr = (struct msghdr) {
.msg_name = ,
.msg_namelen = sizeof(addr),
.msg_iov = ,
.msg_iovlen = 1,
},
};
return sendmmsg(fd, , 1, 0);
}
see https://godbolt.org/z/pwXyzE
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
--- Comment #4 from Yann Droneaud ---
Also with the ({}) GCC extension:
struct a {
int b;
int c;
};
void d(struct a *);
void e(void) {
struct a f = {
.b = ({
int g = 0;
g;
})
};
d();
}
It produces the warning:
: In function 'e':
:10:17: error: missing initializer for field 'c' of 'struct a'
[-Werror=missing-field-initializers]
10 | })};
| ^
:3:7: note: 'c' declared here
3 | int c;
| ^
cc1: all warnings being treated as errors
Compiler returned: 1
See https://godbolt.org/z/VJAuv4
(Note: this example and the one above were reduced by c-reduce
https://embed.cs.utah.edu/creduce/ )
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283
Yann Droneaud changed:
What|Removed |Added
CC||yann at droneaud dot fr
--- Comment #3 from Yann Droneaud ---
I'm experiencing the same issue in multiple cases, even with latest GCC trunk
(10.x).
I believe the following code is C99 conformant, but still trigger an unexpected
warning:
struct a {
int b;
};
struct c {
struct a d;
int e;
};
void f(struct c *);
void g(void) {
struct c h = {.d = (struct a){0}};
f();
}
It produces the following warning:
: In function 'g':
:10:30: error: missing initializer for field 'e' of 'struct c'
[-Weror=missing-field-initializers]
10 | struct c h = {.d = (struct a){0}};
| ^
:6:7: note: 'e' declared here
6 | int e;
| ^
cc1: all warnings being treated as errors
Compiler returned: 1
See https://godbolt.org/z/vQLYRX
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 Eric Gallager changed: What|Removed |Added CC||dmalcolm at gcc dot gnu.org, ||dodji at gcc dot gnu.org --- Comment #2 from Eric Gallager --- cc-ing diagnostics maintainers
[Bug c/82283] Wrong warning with -Wmissing-field-initializers
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 Eric Gallager changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2017-09-29 CC||egallager at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Eric Gallager --- Confirmed that I get the same warning for data1 but not for data2.
