LANG.CAST.ARRAY.TEMP : Array to Pointer Conversion on Temporary Object

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CodeSonar^® 9.2p0

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CodeSecure Inc

C and C++

LANG.CAST.ARRAY.TEMP : Array to Pointer Conversion on Temporary Object

Summary

An array member of a temporary struct or union is cast or coerced to a pointer.

A "temporary struct or union" is an expression of struct or union type that is not an lvalue (that is, does not have an identifiable address).

Modifying an array element in this situation will result in undefined behavior.

Properties

Class Name

Array to Pointer Conversion on Temporary Object

Significance

reliability

Mnemonic

LANG.CAST.ARRAY.TEMP

Categories

MisraC2025	MisraC2025:18.9	An object with temporary lifetime shall not undergo array-to-pointer conversion
MisraC2023	MisraC2023:18.9	An object with temporary lifetime shall not undergo array-to-pointer conversion
Misra2012	Misra2012:18.9	An object with temporary lifetime shall not undergo array-to-pointer conversion
AUTOSARC++14	AUTOSARC++14:A18-1-1	C-style arrays shall not be used.
CERT-C	CERT-C:ARR00-C	Understand how arrays work
	CERT-C:EXP35-C	Do not modify objects with temporary lifetime

Availability

Available for C and C++.

Enabling

Checks for this warning class are disabled by default. To enable them, add the following WARNING_FILTER rule to the project configuration file.

WARNING_FILTER += allow class="Array to Pointer Conversion on Temporary Object"

Example

struct S1 {
    int arr[10];
};

struct S1 svar;
struct S1 getS1(void);

void lang_cast_array_temp( struct S1 sparam ){
    int *p;

    p = svar.arr;                     /* ok: svar is not temporary */
    p[0]++;                           /* this operation has defined behavior */

    p = sparam.arr;                     /* ok: sparam is not temporary */

    p = getS1().arr;         /* 'Array to Pointer Conversion on Temporary Object' warning issued here
                              * - getS1() returns a temporary struct, whose arr field is then coerced to int*
                              */
    p[0]++;                  /* this operation has undefined behavior */

    p = (int*)getS1().arr;   /* 'Array to Pointer Conversion on Temporary Object' warning issued here
                              * - as for previous warning, but casting to int* instead of coercing
                              */
}

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

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