LANG.STRUCT.DECL.MULTIEXT : Multiple External

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LANG.STRUCT.DECL.MULTIEXT : Multiple External Declarations

An identifier with external linkage has multiple associated non-defining extern declarations.

Class Name

Multiple External Declarations

Significance

style

Mnemonic

LANG.STRUCT.DECL.MULTIEXT

Categories

MisraC2023	MisraC2023:8.5	An external object or function shall be declared once in one and only one file
Misra2012	Misra2012:8.5	An external object or function shall be declared once in one and only one file
Misra2004	Misra2004:8.8	An external object or function shall be declared in one and only one file
AUTOSARC++14	AUTOSARC++14:M3-2-3	A type, object or function that is used in multiple translation units shall be declared in one and only one file.
MisraC++2008	MisraC++2008:3-2-3	A type, object or function that is used in multiple translation units shall be declared in one and only one file.
JSF++	JSF++:40	Every implementation file shall include the header files that uniquely define the inline functions, types, and templates used.
	JSF++:139	External objects will not be declared in more than one file.

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="Multiple External Declarations"

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.

Suppose the project consists of LANG.STRUCT.DECL.MULTIEXT.a.c and LANG.STRUCT.DECL.MULTIEXT.b.c.

/* LANG.STRUCT.DECL.MULTIEXT.a.c */
        
int i_oneext=5;  

extern int i_twoext;

int f_oneext( int i){return i;}

extern int f_twoext( int i);

/* LANG.STRUCT.DECL.MULTIEXT.b.c */

extern int i_oneext;                           /* defined in LANG.STRUCT.DECL.MULTIEXT.a.c */

extern int i_twoext;         /* 'Multiple External Declarations' warning issued here:
                              * also declared extern in LANG.STRUCT.DECL.MULTIEXT.a.c,
                              * but not defined there.
                              */

extern int f_oneext( int i);                   /* defined in LANG.STRUCT.DECL.MULTIEXT.a.c */

extern int f_twoext( int i); /* 'Multiple External Declarations' warning issued here:
                              * also declared extern in LANG.STRUCT.DECL.MULTIEXT.a.c,
                              * but not defined there.
                              */

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

LANG.STRUCT.DECL.MULTIEXT : Multiple External Declarations

Summary

Properties

Example

Relevant Configuration File Parameters