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Does not build for strict C99 #339

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opened 2021-04-14 04:51:04 -05:00 by miniwinwm · 10 comments

miniwinwm commented

2021-04-14 04:51:04 -05:00

(Migrated from github.com)

If compiler option -std=c99 is added the build fails because of some inline assembly instructions. While this is not a major problem, some projects require it.

kilograham commented

2021-04-15 15:41:12 -05:00

(Migrated from github.com)

Helpful if you give build output; also how you chose to add -std=c99

miniwinwm commented

2021-04-16 04:02:57 -05:00

(Migrated from github.com)

In my project I added the -std=c99 compiler flag in CMakeCache.txt, after running cmake, like this...

//Flags used by the C compiler during all build types.
CMAKE_C_FLAGS:STRING=-mcpu=cortex-m0plus -mthumb -std=c99

This line...

#include "pico/stdlib.h"

eventually includes platform.h, and it's this code that causes the error...

inline static int32_t __mul_instruction(int32_t a, int32_t b) {
asm ("mul %0, %1" : "+l" (a) : "l" (b) : );
return a;

The errors are first it thinks asm is a function and complains about an implicit declaration, then it barfs on the : in the middle as it's not C.

I have tried reproducing it using the standard examples, for example blink.c. I made the same change to pico-examples/build/CMakeCache.txt, but the blink project built without error so somehow the -std=c99 compiler flags I made is not getting transmitted through the examples build process.

My cmake file is unremarkable...

cmake_minimum_required(VERSION 3.12)
include(pico_sdk_import.cmake)
project(MiniWinSimple)
pico_sdk_init()

add_compile_definitions(RASPBERRY_PI_PICO)

include_directories(
...
)

add_executable(MiniWinSimple
...
)

target_link_libraries(MiniWinSimple pico_stdlib hardware_spi hardware_flash)

pico_add_extra_outputs(MiniWinSimple)

If it helps, the project I tried it on is here...

https://github.com/miniwinwm/miniwinwm/tree/master/RaspberryPi/Pico/MiniWinSimple

In my project I added the -std=c99 compiler flag in CMakeCache.txt, after running cmake, like this... //Flags used by the C compiler during all build types. CMAKE_C_FLAGS:STRING=-mcpu=cortex-m0plus -mthumb -std=c99 This line... #include "pico/stdlib.h" eventually includes platform.h, and it's this code that causes the error... inline static int32_t __mul_instruction(int32_t a, int32_t b) { asm ("mul %0, %1" : "+l" (a) : "l" (b) : ); return a; The errors are first it thinks asm is a function and complains about an implicit declaration, then it barfs on the : in the middle as it's not C. I have tried reproducing it using the standard examples, for example blink.c. I made the same change to pico-examples/build/CMakeCache.txt, but the blink project built without error so somehow the -std=c99 compiler flags I made is not getting transmitted through the examples build process. My cmake file is unremarkable... ``` cmake_minimum_required(VERSION 3.12) include(pico_sdk_import.cmake) project(MiniWinSimple) pico_sdk_init() add_compile_definitions(RASPBERRY_PI_PICO) include_directories( ... ) add_executable(MiniWinSimple ... ) target_link_libraries(MiniWinSimple pico_stdlib hardware_spi hardware_flash) pico_add_extra_outputs(MiniWinSimple) ``` If it helps, the project I tried it on is here... https://github.com/miniwinwm/miniwinwm/tree/master/RaspberryPi/Pico/MiniWinSimple

kilograham commented

2021-04-16 08:30:43 -05:00

(Migrated from github.com)

Does it work with __asm instead of asm?

Does it work with `__asm` instead of `asm`?

miniwinwm commented

2021-04-16 09:44:31 -05:00

(Migrated from github.com)

It gets through the asm problem, but then fails on static_assert in address_mapped.h. I think typeof in sem.c is going to be a problem as well. It looks like that one needs to be __typeof.

kilograham commented

2021-04-16 12:29:21 -05:00

(Migrated from github.com)

Note the best way to specify C99 is to do

project(MiniWinSimple C ASM)
set(CMAKE_C_STANDARD 99)

which will do --std=gnu99 which gets use the asm/typeof stuff. You can add the follow

#ifndef static_assert
#define static_assert _Static_Assert
#endif

for now. you can edit a header, or inject it via the PICO_CONFIG_HEADER_FILES variable:

list(APPEND PICO_CONFIG_HEADER_FILES path/to/foo.h)

and it will be included in all files.

Note the best way to specify C99 is to do ``` project(MiniWinSimple C ASM) set(CMAKE_C_STANDARD 99) ``` which will do `--std=gnu99` which gets use the asm/typeof stuff. You can add the follow ``` #ifndef static_assert #define static_assert _Static_Assert #endif ``` for now. you can edit a header, or inject it via the `PICO_CONFIG_HEADER_FILES` variable: ``` list(APPEND PICO_CONFIG_HEADER_FILES path/to/foo.h) ``` and it will be included in all files.

kilograham commented

2021-04-16 12:31:50 -05:00

(Migrated from github.com)

note that we don't claim to work with C99, however if the changes needed for support arer non invasive we will fix them individually

miniwinwm commented

2021-04-16 14:44:44 -05:00

(Migrated from github.com)

Thanks for your input. I shall work through the problems to see if I can make progress and if it's only trivial changes needed to get it to work I'll add them here.

Wirtos commented

2021-05-07 03:37:36 -05:00

(Migrated from github.com)

C99 has no static assert, but one might use typedef trick to create one if there's no compiler-specific way

#define concat_(a, b) a##b
#define concat(a, b) concat_(a, b)
#define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1]

static_assert(0, "message"); <- compilation error here

C99 has no static assert, but one might use typedef trick to create one if there's no compiler-specific way ``` #define concat_(a, b) a##b #define concat(a, b) concat_(a, b) #define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1] static_assert(0, "message"); <- compilation error here ```

DwayneGit commented

2023-02-23 12:58:50 -06:00

(Migrated from github.com)

I am running into this problem now with trying to compile.

error: expected declaration specifiers or '...' before string constant
  106 |     static_assert( NUM_TIMERS == 4, "");

if i comment it out all good.

any thoughts to adding a check to all the static_asserts:

#if __STDC_VERSION__ >= 201112L
    static_assert( NUM_TIMERS == 4, "");
#endif

or piggy backing off of @Wirtos adding something like this to pico/assert.h:

#if __STDC_VERSION__ < 201112L
  #define concat_(a, b) a##b
  #define concat(a, b) concat_(a, b)
  #define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1]
#endif

I am running into this problem now with trying to compile. ``` error: expected declaration specifiers or '...' before string constant 106 | static_assert( NUM_TIMERS == 4, ""); ``` if i comment it out all good. any thoughts to adding a check to all the static_asserts: ``` #if __STDC_VERSION__ >= 201112L static_assert( NUM_TIMERS == 4, ""); #endif ``` or piggy backing off of @Wirtos adding something like this to pico/assert.h: ``` #if __STDC_VERSION__ < 201112L #define concat_(a, b) a##b #define concat(a, b) concat_(a, b) #define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1] #endif ```

Wirtos commented

2023-02-23 13:08:55 -06:00

(Migrated from github.com)

I am running into this problem now with trying to compile.
error: expected declaration specifiers or '...' before string constant
  106 |     static_assert( NUM_TIMERS == 4, "");
if i comment it out all good.

any thoughts to adding a check to all the static_asserts:
#if __STDC_VERSION__ >= 201112L
    static_assert( NUM_TIMERS == 4, "");
#endif
or piggy backing off of @Wirtos adding something like this to pico/assert.h:
#if __STDC_VERSION__ >= 201112L
  #define concat_(a, b) a##b
  #define concat(a, b) concat_(a, b)
  #define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1]
#endif

Whoops, that one had a little mistake with concat being unused. Indeed this solution should work in most of the use-cases except static asserts declared inside structs or unions, also could add compiler-specific flags to silence unused warnings about declared typedefs

#define concat_(a, b) a##b
#define concat(a, b) concat_(a, b)
#define static_assert(cond, message) typedef char concat(assertion_on_line_, __LINE__)[(cond) ? 1 : -1]

> I am running into this problem now with trying to compile. > > ``` > error: expected declaration specifiers or '...' before string constant > 106 | static_assert( NUM_TIMERS == 4, ""); > ``` > > if i comment it out all good. > > any thoughts to adding a check to all the static_asserts: > > ``` > #if __STDC_VERSION__ >= 201112L > static_assert( NUM_TIMERS == 4, ""); > #endif > ``` > > or piggy backing off of @Wirtos adding something like this to pico/assert.h: > > ``` > #if __STDC_VERSION__ >= 201112L > #define concat_(a, b) a##b > #define concat(a, b) concat_(a, b) > #define static_assert(cond, message) typedef char assertion_on_line_##__LINE__[(cond) ? 1 : -1] > #endif > ``` Whoops, that one had a little mistake with concat being unused. Indeed this solution should work in most of the use-cases except static asserts declared inside structs or unions, also could add compiler-specific flags to silence unused warnings about declared typedefs ```c #define concat_(a, b) a##b #define concat(a, b) concat_(a, b) #define static_assert(cond, message) typedef char concat(assertion_on_line_, __LINE__)[(cond) ? 1 : -1] ```