Re: int a = a (Was: Bart's Language)

On 2025-03-18, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

On 18.03.2025 19:04, Kenny McCormack wrote:

In article <vrc75b$2r4lt$1@dont-email.me>,
David Brown  <david.brown@hesbynett.no> wrote:
...

gcc won't warn until you say '-Wextra', and then only for:
>
   int a = a + 1;

>
People would not normally write "int a = a;".  It is used as a common
idiom meaning "I know it is not clear to the compiler that the variable
is always initialised before use, but /I/ know it is - so disable the
use-without-initialisation warnings for this variable".

>
Wow! - It would never have occurred to me that "int a = a;" being
considered an idiom, let alone a "common idiom".

Suppose the program is well-defined with "int a;"; just the compiler
is not smart enough to analyze it, and so it warns about a potential
use of an uninitialized variable.

When you add this "idiom", you may be introducing undefined behavior
into the declaration.

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