const说明符，用于C中用户定义的数据类型

Question

I have user defined data type

typedef Unsigned int8  COMMAND_TYPE[6];

now I have function like

ConnectCommand(COMMAND_TYPE const command)
{
}

When try to run static analyzer check I get an Misra warning that "The object addressed by the pointer parameter 'command' is not modified and so the pointer could be of type 'pointer to const'"
This is violation of Misra rule 16.7

Though const specifier is used and it appears its not seen here by the misra rule checkin tool and why ?

Answer 1

Certain this is a static analyzer check problem.

The below do the same and both should pass your checker.

ConnectCommand(COMMAND_TYPE const command)
ConnectCommand(const COMMAND_TYPE command)

Although legal code, using a typedef of an array, confused your checker. IMO, this is a design style best avoided.

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Making this community wiki for reference. Suggest deleting once aa good answer comes along.

On review I suspect the problem is Misra - it is giving a false warning. #2, and #3 commented below do the same thing. #4 is redundant with #2, #3.

I will be either deleting this answer or re-work it correctly.

Suggest attempting

 
 
 
  
  typedef Unsigned int8 COMMAND_TYPE[6]; typedef const Unsigned int8 CONST_COMMAND_TYPE[6]; void ConnectCommand(CONST_COMMAND_TYPE command) { ... } COMMAND_TYPE c; ConnectCommand(c);
 
  

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const in ConnectCommand(COMMAND_TYPE const command) { ...} refers to a const command . command is a pointer to objects of type COMMAND_TYPE . const command implies that the pointer should not change in the ConnectCommand() function body.

The "const" in the warning "... type pointer to const" recommends using a const to the type of object pointed to by command . This is because the data pointed to by command is not changed.

 
 
 
  
  // add could drop this const // | | ConnectCommand(const COMMAND_TYPE const command)