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The C Standard identifies five two distinct situations in which undefined behavior (UB) may arise as a result of invoking a function using a declaration that is incompatible with its definition or by supplying incorrect types or numbers of arguments:
| UB | Description |
A pointer is used to call a function whose type is not compatible with the referenced type (6.3.2.3). | |
For a call to a function without a function prototype in scope, the number of arguments does not equal the number of parameters (6.5.2.2). | |
For a call to a function without a function prototype in scope where the function is defined with a function prototype, either the prototype ends with an ellipsis or the types of the arguments after promotion are not compatible with the types of the parameters (6.5.2.2). | |
| For a call to a function without a function prototype in scope where the function is not defined with a function prototype, the types of the arguments after promotion are not compatible with those of the parameters after promotion (with certain exceptions) (6.5.2.2). | |
A pointer is used to call a function whose type is not compatible with the referenced type (6.3.2.3). | |
A function is defined with a type that is not compatible with the type (of the expression) pointed to by the expression that denotes the called function (6.5.2.2). |
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A pointer to a function of one type may be converted to a pointer to a function of another type and back again; the result shall compare equal to the original pointer. If a converted pointer is used to call a function whose type is not compatible with the referenced type, the behavior is undefined.
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <stdio.h>
#include <string.h>
char *(*fp)();
int main(void) {
const char *c;
fp = strchr;
c = fp('e', "Hello");
printf("%s\n", c);
return 0;
} |
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| Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| incompatible-argument-type parameter-match parameter-match-computed parameter-match-type | Fully checked | ||||||
| Axivion Bauhaus Suite |
| CertC-EXP37 | |||||||
| CodeSonar |
| LANG.FUNCS.APM | Array parameter mismatch | ||||||
| Compass/ROSE | Can detect some violations of this rule. In particular, it ensures that all calls to | ||||||||
| Coverity |
| MISRA C 2012 Rule 8.2 MISRA C 2012 Rule 17.3 | Implemented Relies on functions declared with prototypes, allow compiler to check | ||||||
| Cppcheck Premium |
| premium-cert-exp37-cFully implemented | |||||||
| CC2.EXP37 | Partially implemented | |||||||
| EDG | |||||||||
| GCC |
| Can detect violation of this rule when the | |||||||
| Helix QAC |
| C1331, C1332, C1333, C3002, C3320, C3335 C++0403 | |||||||
| Klocwork |
| MISRA.FUNC.UNMATCHED.PARAMS | |||||||
| LDRA tool suite |
| 41 D, 21 S, 98 S, 170 S, 496 S, 576 S | Partially implemented | ||||||
| Parasoft C/C++test |
| CERT_C-EXP37-a | Conversions shall not be performed between non compatible pointer to a function types | ||||||
| Polyspace Bug Finder |
| Checks for:
Rule partially covered. | |||||||
| PVS-Studio |
| V540, V541, V549, V575, V632, V639, V666, V671, V742, V743, V764, V1004 | |||||||
| SonarQube C/C++ Plugin |
| S930 | Detects incorrect argument count | ||||||
| RuleChecker |
| parameter-match parameter-match-type | Partially checked | ||||||
| TrustInSoft Analyzer |
| unclassified ("function type matches") | Partially verified (see one compliant and one non-compliant example). |
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