LANG.ID.ND.EXT : Non-distinct Identifiers: External Names

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Two or more external identifiers are not distinct. The identifiers do not need to be declared in the same file.

Specifically, two or more identifiers have the same first N (case-sensitive) characters, where:

N depends on the setting of SIGNIFICANCE_LEN_EXTERN, and

all the identifiers have external linkage.

See Identifier Classes for related warning classes.

Class Name

Non-distinct Identifiers: External Names

Significance

style

Mnemonic

LANG.ID.ND.EXT

Categories

MisraC2023	MisraC2023:5.1	External identifiers shall be distinct
Misra2012	Misra2012:5.1	External identifiers shall be distinct
Misra2004	Misra2004:5.1	Identifiers (internal and external) shall not rely on the significance of more than 31 characters
CWE	CWE:710	Improper Adherence to Coding Standards
CERT-C	CERT-C:DCL23-C	Guarantee that mutually visible identifiers are unique
JSF++	JSF++:46	User-specified identifiers (internal and external) will not rely on significance of more than 64 characters.

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="Non-distinct Identifiers: External Names"

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.

/* pair 1: distinct in first 6 characters */
extern int okA;                      
extern int okB;     

/* pair 2:  distinct in first 31 characters; not distinct in first 6 characters
 *  - 'Non-distinct Identifiers: External Names' warning issued for C90 only */
extern int ok99onlyA; 
extern int ok99onlyB;    

/* pair 3:  not distinct in first 31 characters
 * - 'Non-distinct Identifiers: External Names' warning issued for both  C90 and C99 */
extern int abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz1;     
extern int abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz2;

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

LANG.ID.ND.EXT : Non-distinct Identifiers: External Names

Summary

Properties

Example

Relevant Configuration File Parameters