IAR编译失败，CCS编译成功。 类型不兼容

Question

After developing a new firmware (main and libraries) with CCS for my CC2538, all errors are debugged, and now, device is working fine.

As from CCS I can not flash the firmware permanently, I'm working with IAR to develop this action.

On IAR, I have created the workspace, the project and included all libraries and files needed to compile the firmware. But, compilation fails due to incompatible types errors.

• Error[Pe144]: a value of type "int" cannot be used to initialize an entity of type "signed short *"

   int16_t *accData[3] = malloc(sizeof(int16_t)); 

• Error[Pe513]: a value of type "int" cannot be assigned to an entity of type "signed short *"

   int16_t *accData[3] = malloc(sizeof(int16_t)); 

• Error[Pe120]: return value type ("signed short **") does not match the function type ("signed short*")

   int16_t * lsm303d_readAccData(void) { int16_t *accData[3] = malloc(sizeof(int16_t)); ... return accData; } 

Which is the root cause of these errors? Maybe, any option of the compiler? Do I need to add any file? Or prototype on the code?

KR!

Answer 1

The first error is somewhat misleading. It seems to indicate that you forgot to include <stdlib.h> , so malloc is undefined and the compiler assumes it returns int .

In any case, you are assigning a pointer to an array: this is incorrect.

Returning the address of a local automatic array is incorrect too.

You should define accData as a pointer instead of an array, and make it point to an allocated array of int16_t . You seem to want this array to hold 3 elements, otherwise modify the code accordingly:

#include <stdlib.h>

int16_t *lsm303d_readAccData(void) {
    int16_t *accData = malloc(sizeof(int16_t) * 3);
    ...
    return accData;
}

You should configure the compiler to issue more warnings and refuse obsolete constructions such as implicit int. For gcc , add -std=c99 or -std=c11 and -Wall -Wextra -Werror .

Answer 2

Which is the root cause of these errors?

"a value of type "int"" is the root cause. There should be no int here! Just the signed short* (which is your int16_t*) and a void* from malloc.

This is because you are using a C90 compiler and forgot to #include <stdlib.h> . Upon finding a function with no prototype, C90 would implicitly assume you want a function returning int, which explains the compiler errors "a value of type "int"". But malloc actually returns a void* , so this is a severe bug. Solve this by including the header stdlib.h where malloc is found.

This undesired and irrational behavior of the language was fixed 17 years ago. Consider using a modern compiler instead, or configure your compiler to use the current C language standard (ISO 9899:2011).

That being said, this code doesn't make any sense either:

int16_t *accData[3] = malloc(sizeof(int16_t));

You probably meant

int16_t *accData = malloc( sizeof(int16_t[3]) );