Our website uses cookies to enhance your browsing experience.
Accept
to the top
close form

Fill out the form in 2 simple steps below:

Your contact information:

Step 1
Congratulations! This is your promo code!

Desired license type:

Step 2
Team license
Enterprise license
** By clicking this button you agree to our Privacy Policy statement
close form
Request our prices
New License
License Renewal
--Select currency--
USD
EUR
* By clicking this button you agree to our Privacy Policy statement

close form
Free PVS‑Studio license for Microsoft MVP specialists
* By clicking this button you agree to our Privacy Policy statement

close form
To get the licence for your open-source project, please fill out this form
* By clicking this button you agree to our Privacy Policy statement

close form
I am interested to try it on the platforms:
* By clicking this button you agree to our Privacy Policy statement

close form
check circle
Message submitted.

Your message has been sent. We will email you at


If you haven't received our response, please do the following:
check your Spam/Junk folder and click the "Not Spam" button for our message.
This way, you won't miss messages from our team in the future.

>
>
>
V2625. MISRA. Identifiers that define o…
menu mobile close menu
Analyzer diagnostics
General Analysis (C++)
General Analysis (C#)
General Analysis (Java)
Micro-Optimizations (C++)
Diagnosis of 64-bit errors (Viva64, C++)
Customer specific requests (C++)
MISRA errors
AUTOSAR errors
OWASP errors (C#)
Problems related to code analyzer
Additional information
toggle menu Contents

V2625. MISRA. Identifiers that define objects or functions with external linkage shall be unique.

Jan 31 2024

The diagnostic rule is based on the MISRA (Motor Industry Software Reliability Association) software development guidelines.

The rule is relevant only for C. An identifier with external linkage should be unique in a program. The name should not be used by other identifiers that have a different linkage type (no linkage, internal linkage) within functions or other translation units. The rule applies to both objects and functions.

Note. To search for non-unique identifiers in different translation units, enable the intermodular analysis mode.

Here is an example:

int var;  // external linkage

void foo()
{
  short var;  // no linkage
}

In the code fragment above, the 'var' identifier with external linkage is hidden by a local variable in the 'foo' function. The fixed code looks like this:

int var;  // external linkage

void foo()
{
  short temp;  // no linkage
}

Let's look at another example, but this one is based on the contents of two files from the same project:

// file1.c
int x;             // external linkage
static int y;      // internal linkage

static void bar(); // internal linkage

// file2.c
void bar()  // external linkage       
{
  int y;    // no linkage
}    

void foo()  // external linkage 
{                  
  int x;    // no linkage 
}

The 'x' identifiers from 'file1.c' and 'bar' from 'file2.c' have external linkage and are not unique, so they violate the rule. The 'y' identifier is not unique, either. However, since it has internal linkage in 'file1.c' and no linkage in 'file2.c', the rule is not violated for this name.

Here is the fixed code:

// file1.c
static int x;        // internal linkage
static int y;        // internal linkage

static void func();  // internal linkage

// file2.c
void bar()  // external linkage         
{
  int y;    // no linkage
}    

void foo()  // external linkage 
{                  
  int x;    // no linkage 
}