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If an attempt is made to refer to an object defined with a volatile-qualified type through use of an lvalue with non-volatile-qualified type, the behavior is undefined.

(See also undefined behavior 65 of Appendix J.)

Noncompliant Code Example

In this example, a volatile object is accessed through a non-volatile-qualified reference, resulting in undefined behavior.

static volatile int **ipp;
static int *ip;
static volatile int i = 0;

printf("i = %d.\n", i);

ipp = &ip; /* produces warnings in modern compilers */
ipp = (int**) &ip; /* constraint violation, also produces warnings */
*ipp = &i; /* valid */
if (*ip != 0) { /* valid */
  /* ... */
}

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ISO/IEC 9899:2011 Section 6.7.3, "Type qualifiers," and Section 6.5.16.1, "Simple assignment"

ISO/IEC TR 24772 "HFC Pointer casting and pointer type changes" and "IHN Type system"

MISRA Rule 11.5

Bibliography

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