MISRA C:2004
Perforce QAC for C 2026.1
(MISRA C:2004 plus Technical Corrigendum 1)
Rule Enforcement Summary
| Total | ||
|---|---|---|
| a | Total Number of Rules | 142 |
| b | Total Number of 'Not Statically Enforceable' Rules (Assisted/Unassisted) | 9 |
| c | Total Number of Enforceable Rules (a-b) | 133 |
| d | Total Number of Enforced Rules | 132 |
| e | Total Number of Unenforced Rules (c-d) | 1 |
| f | Enforced Rules Percentage (d/c) | 99% |
| g | Unenforced Rules Percentage (e/c) | 1% |
| Id | Description | Category | Enforced |
|---|---|---|---|
| Rule-1.1 | All code shall conform to ISO/IEC 9899:1990 C programming language, ISO 9899, amended and corrected by ISO/IEC 9899/COR1:1995,ISO/IEC 9899/AMD1:1995, and ISO/IEC 9899/COR2: 1996192 | Required | Yes |
| Rule-1.2 | No reliance shall be placed on undefined or unspecified behaviour. | Required | Yes |
| Rule-2.1 | Assembly language shall be encapsulated and isolated. | Required | Yes |
| Rule-2.2 | Source code shall only use C-style comments. | Required | Yes |
| Rule-2.3 | The character sequence /* shall not be used within a comment. | Required | Yes |
| Rule-3.1 | All usage of implementation-defined behaviour shall be documented. | Required | Yes |
| Rule-3.4 | All uses of the #pragma directive shall be documented and explained. | Required | Yes |
| Rule-4.1 | Only those escape sequences that are defined in the ISO C standard shall be used. | Required | Yes |
| Rule-4.2 | Trigraphs shall not be used. | Required | Yes |
| Rule-5.1 | Identifiers (internal and external) shall not rely on the significance of more than 31 characters. | Required | Yes |
| Rule-5.2 | Identifiers in an inner scope shall not use the same name as an identifier in an outer scope, and therefore hide that identifier. | Required | Yes |
| Rule-5.3 | A typedef name shall be a unique identifier. | Required | Yes |
| Rule-5.4 | A tag name shall be a unique identifier. | Required | Yes |
| Rule-5.5 | No object or function identifier with static storage duration should be reused. | Advisory | Yes |
| Rule-5.6 | No identifier in one name space should have the same spelling as an identifier in another name space, with the exception of structure member and union member names. | Advisory | Yes |
| Rule-5.7 | No identifier name should be reused. | Advisory | No |
| Rule-6.1 | The plain char type shall be used only for the storage and use of character values. | Required | Yes |
| Rule-6.2 | Signed and unsigned char type shall be used only for the storage and use of numeric values. | Required | Yes |
| Rule-6.3 | Typedefs that indicate size and signedness should be used in place of the basic numerical types. | Advisory | Yes |
| Rule-6.4 | Bit fields shall only be defined to be of type unsigned int or signed int. | Required | Yes |
| Rule-6.5 | Bit fields of signed type shall be at least 2 bits long. | Required | Yes |
| Rule-7.1 | Octal constants (other than zero) and octal escape sequences shall not be used. | Required | Yes |
| Rule-8.1 | Functions shall have prototype declarations and the prototype shall be visible at both the function definition and call. | Required | Yes |
| Rule-8.2 | Whenever an object or function is declared or defined, its type shall be explicitly stated. | Required | Yes |
| Rule-8.3 | For each function parameter the type given in the declaration and definition shall be identical, and the return types shall also be identical. | Required | Yes |
| Rule-8.4 | If objects or functions are declared more than once their types shall be compatible. | Required | Yes |
| Rule-8.5 | There shall be no definitions of objects or functions in a header file. | Required | Yes |
| Rule-8.6 | Functions shall be declared at file scope. | Required | Yes |
| Rule-8.7 | Objects shall be defined at block scope if they are only accessed from within a single function. | Required | Yes |
| Rule-8.8 | An external object or function shall be declared in one and only one file. | Required | Yes |
| Rule-8.9 | An identifier with external linkage shall have exactly one external definition. | Required | Yes |
| Rule-8.10 | All declarations and definitions of objects or functions at file scope shall have internal linkage unless external linkage is required. | Required | Yes |
| Rule-8.11 | The static storage class specifier shall be used in definitions and declarations of objects and functions that have internal linkage. | Required | Yes |
| Rule-8.12 | When an array is declared with external linkage, its size shall be stated explicitly or defined implicitly by initialisation. | Required | Yes |
| Rule-9.1 | All automatic variables shall have been assigned a value before being used. | Required | Yes |
| Rule-9.2 | Braces shall be used to indicate and match the structure in the non-zero initialisation of arrays and structures. | Required | Yes |
| Rule-9.3 | In an enumerator list, the '=' construct shall not be used to explicitly initialise members other than the first, unless all items are explicitly initialised. | Required | Yes |
| Rule-10.1 | The value of an expression of integer type shall not be implicitly converted to a different underlying type if: a) it is not a conversion to a wider integer type of the same signedness, or b) expression is complex, or c) the expression is not constant and is a function argument, or d) the expression is not constant and is a return expression | Required | Yes |
| Rule-10.2 | The value of an expression of floating type shall not be implicitly converted to a different type if: a) it is not a conversion to a wider floating type, or b) the expression is complex, or c) the expression is a function argument, or d) the expression is a return expression | Required | Yes |
| Rule-10.3 | The value of a complex expression of integer type shall only be cast to a type of the same signedness that is no wider than the underlying type of the expression. | Required | Yes |
| Rule-10.4 | The value of a complex expression of floating type shall only be cast to a floating type that is narrower or of the same size. | Required | Yes |
| Rule-10.5 | If the bitwise operators ~ and << are applied to an operand of underlying type unsigned char or unsigned short, the result shall be immediately cast to the underlying type of the operand. | Required | Yes |
| Rule-10.6 | A "U" suffix shall be applied to all constants of unsigned type. | Required | Yes |
| Rule-11.1 | Conversions shall not be performed between a pointer to a function and any type other than an integral type. | Required | Yes |
| Rule-11.2 | Conversions shall not be performed between a pointer to object and any type other than an integral type, another pointer to object type or a pointer to void. | Required | Yes |
| Rule-11.3 | A cast should not be performed between a pointer type and an integral type. | Advisory | Yes |
| Rule-11.4 | A cast should not be performed between a pointer to object type and a different pointer to object type. | Advisory | Yes |
| Rule-11.5 | A cast shall not be performed that removes any const or volatile qualification from the type addressed by a pointer. | Required | Yes |
| Rule-12.1 | Limited dependence should be placed on C's operator precedence rules in expressions. | Advisory | Yes |
| Rule-12.2 | The value of an expression shall be the same under any order of evaluation that the standard permits. | Required | Yes |
| Rule-12.3 | The sizeof operator shall not be used on expressions that contain side effects. | Required | Yes |
| Rule-12.4 | The right hand operand of a logical && or || operator shall not contain side effects. | Required | Yes |
| Rule-12.5 | The operands of a logical && or || shall be primary-expressions. | Required | Yes |
| Rule-12.6 | The operands of logical operators (&&, || and !) should be effectively Boolean. Expressions that are effectively Boolean should not be used as operands to operators other than (&&, ||, !, =, ==, != and ?:). | Advisory | Yes |
| Rule-12.7 | Bitwise operators shall not be applied to operands whose underlying type is signed. | Required | Yes |
| Rule-12.8 | The right hand operand of a shift operator shall lie between zero and one less than the width in bits of the underlying type of the left hand operand. | Required | Yes |
| Rule-12.9 | The unary minus operator shall not be applied to an expression whose underlying type is unsigned. | Required | Yes |
| Rule-12.10 | The comma operator shall not be used. | Required | Yes |
| Rule-12.11 | Evaluation of constant unsigned integer expressions should not lead to wrap-around. | Advisory | Yes |
| Rule-12.12 | The underlying bit representations of floating-point values shall not be used. | Required | Yes |
| Rule-12.13 | The increment (++) and decrement (--) operators should not be mixed with other operators in an expression. | Advisory | Yes |
| Rule-13.1 | Assignment operators shall not be used in expressions that yield a Boolean value. | Required | Yes |
| Rule-13.2 | Tests of a value against zero should be made explicit, unless the operand is effectively Boolean. | Advisory | Yes |
| Rule-13.3 | Floating-point expressions shall not be tested for equality or inequality. | Required | Yes |
| Rule-13.4 | The controlling expression of a for statement shall not contain any objects of floating type. | Required | Yes |
| Rule-13.5 | The three expressions of a for statement shall be concerned only with loop control. | Required | Yes |
| Rule-13.6 | Numeric variables being used within a for loop for iteration counting shall not be modified in the body of the loop. | Required | Yes |
| Rule-13.7 | Boolean operations whose results are invariant shall not be permitted. | Required | Yes |
| Rule-14.1 | There shall be no unreachable code. | Required | Yes |
| Rule-14.2 | All non-null statements shall either (i) have at least one side effect however executed, or (ii) cause control flow to change. | Required | Yes |
| Rule-14.3 | Before preprocessing, a null statement shall only occur on a line by itself; it may be followed by a comment provided that the first character following the null statement is a white-space character. | Required | Yes |
| Rule-14.4 | The goto statement shall not be used. | Required | Yes |
| Rule-14.5 | The continue statement shall not be used. | Required | Yes |
| Rule-14.6 | For any iteration statement there shall be at most one break statement used for loop termination. | Required | Yes |
| Rule-14.7 | A function shall have a single point of exit at the end of the function. | Required | Yes |
| Rule-14.8 | The statement forming the body of a switch, while, do ... while or for statement shall be a compound statement. | Required | Yes |
| Rule-14.9 | An if (expression) construct shall be followed by a compound statement. The else keyword shall be followed by either a compound statement, or another if statement. | Required | Yes |
| Rule-14.10 | All if ... else if constructs shall be terminated with an else clause. | Required | Yes |
| Rule-15.0 | The MISRA C switch syntax shall be used. | Required | Yes |
| Rule-15.1 | A switch label shall only be used when the most closely-enclosing compound statement is the body of a switch statement. | Required | Yes |
| Rule-15.2 | An unconditional break statement shall terminate every non-empty switch clause. | Required | Yes |
| Rule-15.3 | The final clause of a switch statement shall be the default clause. | Required | Yes |
| Rule-15.4 | A switch expression shall not represent a value that is effectively Boolean. | Required | Yes |
| Rule-15.5 | Every switch statement shall have at least one case clause. | Required | Yes |
| Rule-16.1 | Functions shall not be defined with a variable number of arguments. | Required | Yes |
| Rule-16.2 | Functions shall not call themselves, either directly or indirectly. | Required | Yes |
| Rule-16.3 | Identifiers shall be given for all of the parameters in a function prototype declaration. | Required | Yes |
| Rule-16.4 | The identifiers used in the declaration and definition of a function shall be identical. | Required | Yes |
| Rule-16.5 | Functions with no parameters shall be declared and defined with the parameter list void. | Required | Yes |
| Rule-16.6 | The number of arguments passed to a function shall match the number of parameters. | Required | Yes |
| Rule-16.7 | A pointer parameter in a function prototype should be declared as pointer to const if the pointer is not used to modify the addressed object. | Advisory | Yes |
| Rule-16.8 | All exit paths from a function with non-void return type shall have an explicit return statement with an expression. | Required | Yes |
| Rule-16.9 | A function identifier shall only be used with either a preceding &, or with a parenthesised parameter list, which may be empty. | Required | Yes |
| Rule-16.10 | If a function returns error information, then that error information shall be tested. | Required | Yes |
| Rule-17.1 | Pointer arithmetic shall only be applied to pointers that address an array or array element. | Required | Yes |
| Rule-17.2 | Pointer subtraction shall only be applied to pointers that address elements of the same array. | Required | Yes |
| Rule-17.3 | >, >=, <, <= shall not be applied to pointer types except where they point to the same array. | Required | Yes |
| Rule-17.4 | Array indexing shall be the only allowed form of pointer arithmetic. | Required | Yes |
| Rule-17.5 | The declaration of objects should contain no more than 2 levels of pointer indirection. | Advisory | Yes |
| Rule-17.6 | The address of an object with automatic storage shall not be assigned to another object that may persist after the first object has ceased to exist. | Required | Yes |
| Rule-18.1 | All structure and union types shall be complete at the end of a translation unit. | Required | Yes |
| Rule-18.2 | An object shall not be assigned to an overlapping object. | Required | Yes |
| Rule-18.4 | Unions shall not be used. | Required | Yes |
| Rule-19.1 | #include statements in a file should only be preceded by other preprocessor directives or comments. | Advisory | Yes |
| Rule-19.2 | Non-standard characters should not occur in header file names in #include directives. | Advisory | Yes |
| Rule-19.3 | The #include directive shall be followed by either a <filename> or "filename" sequence. | Required | Yes |
| Rule-19.4 | C macros shall only expand to a braced initialiser, a constant, a string literal, a parenthesised expression, a type qualifier, a storage class specifier, or a do-while-zero construct. | Required | Yes |
| Rule-19.5 | Macros shall not be #define'd or #undef'd within a block. | Required | Yes |
| Rule-19.6 | #undef shall not be used. | Required | Yes |
| Rule-19.7 | A function should be used in preference to a function-like macro. | Advisory | Yes |
| Rule-19.8 | A function-like macro shall not be invoked without all of its arguments. | Required | Yes |
| Rule-19.9 | Arguments to a function-like macro shall not contain tokens that look like preprocessing directives. | Required | Yes |
| Rule-19.10 | In the definition of a function-like macro each instance of a parameter shall be enclosed in parentheses unless it is used as the operand of # or ##. | Required | Yes |
| Rule-19.11 | All macro identifiers in preprocessor directives shall be defined before use, except in #ifdef and #ifndef preprocessor directives and the defined() operator. | Required | Yes |
| Rule-19.12 | There shall be at most one occurrence of the # or ## preprocessor operators in a single macro definition. | Required | Yes |
| Rule-19.13 | The # and ## preprocessor operators should not be used. | Advisory | Yes |
| Rule-19.14 | The defined preprocessor operator shall only be used in one of the two standard forms. | Required | Yes |
| Rule-19.15 | Precautions shall be taken in order to prevent the contents of a header file being included twice. | Required | Yes |
| Rule-19.16 | Preprocessing directives shall be syntactically meaningful even when excluded by the preprocessor. | Required | Yes |
| Rule-19.17 | All #else, #elif and #endif preprocessor directives shall reside in the same file as the #if or #ifdef directive to which they are related. | Required | Yes |
| Rule-20.1 | Reserved identifiers, macros and functions in the standard library, shall not be defined, redefined or undefined. | Required | Yes |
| Rule-20.2 | The names of standard library macros, objects and functions shall not be reused. | Required | Yes |
| Rule-20.3 | The validity of values passed to library functions shall be checked. | Required | Yes |
| Rule-20.4 | Dynamic heap memory allocation shall not be used. | Required | Yes |
| Rule-20.5 | The error indicator errno shall not be used. | Required | Yes |
| Rule-20.6 | The macro offsetof, in library <stddef.h>, shall not be used. | Required | Yes |
| Rule-20.7 | The setjmp macro and the longjmp function shall not be used. | Required | Yes |
| Rule-20.8 | The signal handling facilities of <signal.h> shall not be used. | Required | Yes |
| Rule-20.9 | The input/output library <stdio.h> shall not be used in production code. | Required | Yes |
| Rule-20.10 | The library functions atof, atoi and atol from library <stdlib.h> shall not be used. | Required | Yes |
| Rule-20.11 | The library functions abort, exit, getenv and system from library <stdlib.h> shall not be used. | Required | Yes |
| Rule-20.12 | The time handling functions of library <time.h> shall not be used. | Required | Yes |
| Rule-21.1 | Minimisation of run-time failures shall be ensured by the use of at least one of (a) static analysis tools/techniques; (b) dynamic analysis tools/techniques; (c) explicit coding of checks to handle run-time faults | Required | Yes |
Not Statically Enforceable Rules
| Id | Description | Assisted |
|---|---|---|
| Rule-1.3 | Multiple compilers and/or languages shall only be used if there is a common defined interface standard for object code to which the languages/compilers/assemblers conform. | Unassisted |
| Rule-1.4 | The compiler/linker shall be checked to ensure that 31 character significance and case sensitivity are supported for external identifiers. | Unassisted |
| Rule-1.5 | Floating-point implementations should comply with a defined floating-point standard. | Unassisted |
| Rule-2.4 | Sections of code should not be 'commented out'. | Assisted |
| Rule-3.2 | The character set and the corresponding encoding shall be documented. | Unassisted |
| Rule-3.3 | The implementation of integer division in the chosen compiler should be determined, documented and taken into account. | Unassisted |
| Rule-3.5 | If it is being relied upon, the implementation-defined behaviour and packing of bitfields shall be documented. | Unassisted |
| Rule-3.6 | All libraries used in production code shall be written to comply with the provisions of this document, and shall have been subject to appropriate validation. | Unassisted |
| Rule-18.3 | An area of memory shall not be reused for unrelated purposes. | Unassisted |
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