C and C++

LANG.ID.AMBIG : Typographically Ambiguous Identifiers

Summary

Two or more non-identical identifiers are both in scope and may be confused for one another because their only differences involve characters that are typographically similar:

Typographically Ambiguous Characters Description
0 / O numeric zero / capital o
1 / I / l numeric one / capital i / lower case L
2 / Z numeric two / capital z
5 / S numeric five / capital s
8 / B numeric eight / capital b
h / n lower case H / lower case N
rn / m lower case RN / lower case M
a..z / A..Z lower case character / upper case equivalent
strA_strB / strAstrB a string containing an underscore / the equivalent string without the underscore

Properties

Class Name Typographically Ambiguous Identifiers
Significance style
Mnemonic LANG.ID.AMBIG
Categories
MisraC2023 MisraC2023:D.4.5 Identifiers in the same name space with overlapping visibility should be typographically unambiguous
Misra2012 Misra2012:D.4.5 Identifiers in the same name space with overlapping visibility should be typographically unambiguous
AUTOSARC++14 AUTOSARC++14:M2-10-1 Different identifiers shall be typographically unambiguous.
MisraC++2008 MisraC++2008:2-10-1 Different identifiers shall be typographically unambiguous.
CWE CWE:1007 Insufficient Visual Distinction of Homoglyphs Presented to User
CERT-C CERT-C:DCL02-C Use visually distinct identifiers
JSF++ JSF++:48 Identifiers will not be typographically ambiguous.
Availability Available for C and C++.
Enabling Checks for this warning class are disabled by default, and require the unnormalized C ASTs for the project. To enable them, add the following WARNING_FILTER rule and RETAIN_UNNORMALIZED_C_AST specification to the project configuration file. 
RETAIN_UNNORMALIZED_C_AST = Yes
INCREMENTAL_BUILD = No
WARNING_FILTER += allow class="Typographically Ambiguous Identifiers"
Note that retaining the unnormalized ASTs will increase the disk space used to store the project representation, and may make the analysis take longer.

Incrementality Note: This warning class is not available for incremental analyses, even if the class is explicitly enabled.

Example 

int a0;
int b1;
int c2;
int d5;
int e8;
int fh;               /* 'Typographically Ambiguous Identifiers' warning issued here */
int myint;
double mydouble;
int ma;
        
void ID_AMBIG(void){
    int aO;           /* 'Typographically Ambiguous Identifiers' warning issued here */
    int bI;           /* 'Typographically Ambiguous Identifiers' warning issued here */
    int cZ;           /* 'Typographically Ambiguous Identifiers' warning issued here */
    float dS;         /* 'Typographically Ambiguous Identifiers' warning issued here */
    int * eB;         /* 'Typographically Ambiguous Identifiers' warning issued here */
    int MyInt;        /* 'Typographically Ambiguous Identifiers' warning issued here */
    double my_double; /* 'Typographically Ambiguous Identifiers' warning issued here */
    int rna;          /* 'Typographically Ambiguous Identifiers' warning issued here */

    int g1;                                   /* locals for fn() are not in scope */
    /* ... */
}

void fn(void){ 
    int bl;           /* 'Typographically Ambiguous Identifiers' warning issued here */
    int gl;                                  /* locals for ID_AMBIG() are not in scope */

    /* ... */
}

Relevant Configuration File Parameters

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