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Fix minor unused/uninitialized warnings from GCC 12.3.0 #1786

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Fix minor unused/uninitialized warnings from GCC 12.3.0 #1786

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10ef4c8
Fix minor unused/uninitialized warnings from GCC 12
earlephilhower Aug 9, 2024
aaa4fa4
Take care of PICO_PIO_USE_GPIO_BASE case, too
earlephilhower Aug 9, 2024
414b9ea
Update timer.h
earlephilhower Aug 20, 2024
ddcaa6b
Update timer.h
earlephilhower Aug 20, 2024
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7 changes: 4 additions & 3 deletions src/rp2_common/hardware_pio/include/hardware/pio.h
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Original file line number Diff line number Diff line change
Expand Up @@ -647,9 +647,10 @@ static inline void sm_config_set_mov_status(pio_sm_config *c, enum pio_mov_statu
* \return the default state machine configuration which can then be modified.
*/
static inline pio_sm_config pio_get_default_sm_config(void) {
pio_sm_config c = {0};
#if PICO_PIO_USE_GPIO_BASE
c.pinhi = -1;
#if PICO_PIO_USE_GPIO_BASE
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what is the warning what version of the compiler?

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arm-none-eabi-gcc (GCC) 12.3.0 using -Wall -Wextra

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Can you give the full output off gcc --version and/or say where you got it.

I'm tempted not to fix this as this is a compiler bug (and the fix is ugly/brittle), but if i can actually get an exact compiler which has this problem, i can see if it supports suppressing the warning

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@earlephilhower earlephilhower Aug 20, 2024 •
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I don't think this is a compiler issue so much as a C vs. C++ issue.

In C++ {0} will only set the 1st member of the structure to 0 because it's taking that as a positional initializer. In C, IIRC, {0} will effectively bzero the struct, which might be where the confusion is stemming from. You can include the SDK headers in C++ code, and when that happens the warning pops up.

This is with plain Ubuntu 20.04 GCC 9, not even the ARM x-compiler using a simple example to avoid a bunch of -Is. Just a struct with >1 member being set to {0}.

earle@amd:~/Arduino/hardware/pico/rp2040$ gcc --version
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

earle@amd:~/Arduino/hardware/pico/rp2040$ cat a.c
#include <stdio.h>
struct t {
    int a;
    int b;
};
void dummy() {
    struct t a = {0};
    printf("%d\n", a.b);
}
earle@amd:~/Arduino/hardware/pico/rp2040$ cp a.c a.cpp
earle@amd:~/Arduino/hardware/pico/rp2040$ gcc -Wall -Wextra -c  a.c
<note no warnings>
earle@amd:~/Arduino/hardware/pico/rp2040$ g++ -Wall -Wextra -c  a.c
a.c: In function ‘void dummy()’:
a.c:7:20: warning: missing initializer for member ‘t::b’ [-Wmissing-field-initializers]
    7 |     struct t a = {0};
      |

(for completeness I see I used .c and not .cpp in the g++ line, so here that is, too:

earle@amd:~/Arduino/hardware/pico/rp2040$ g++ -Wall -Wextra -c  a.cpp
a.cpp: In function ‘void dummy()’:
a.cpp:7:20: warning: missing initializer for member ‘t::b’ [-Wmissing-field-initializers]
    7 |     struct t a = {0};
      |                    ^

and for completeness, because the SDK includes are extern "C"'d, that doesn't affect the compilation, only the name mangling:

earle@amd:~/Arduino/hardware/pico/rp2040$ cat a.cpp
#include <stdio.h>
extern "C" {
struct t {
    int a;
    int b;
};
void dummy() {
    struct t a = {0};
    printf("%d\n", a.b);
}
}
earle@amd:~/Arduino/hardware/pico/rp2040$ g++ -Wall -Wextra -c  a.cpp
a.cpp: In function ‘void dummy()’:
a.cpp:8:20: warning: missing initializer for member ‘t::b’ [-Wmissing-field-initializers]
    8 |     struct t a = {0};
      |                    ^

pio_sm_config c = {0, 0, 0, 0, -1};
#else
pio_sm_config c = {0, 0, 0, 0};
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#endif
sm_config_set_clkdiv_int_frac(&c, 1, 0);
sm_config_set_wrap(&c, 0, 31);
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