warning about missing format string annotations

Hi,

On 2022-09-15 21:18:03 +0000, Tom Lane wrote:
> We're so used to having the compiler check this stuff for us that
> a printf-like function without pg_attribute_printf is a land mine.
> I wonder if there is a way to detect such omissions.

gcc has -Wsuggest-attribute=format - but unfortunately its heuristics appear
to be too simplistic to catch many omission. It doesn't catch this one, for
example. But it may still be worth trying out in a few more cases.

-Wsuggest-attribute=format
-Wmissing-format-attribute
Warn about function pointers that might be candidates for "format" attributes. Note these are only possible candidates, not absolute ones.
GCC guesses that function pointers with "format" attributes that are used in assignment, initialization, parameter passing or return
statements should have a corresponding "format" attribute in the resulting type. I.e. the left-hand side of the assignment or
initialization, the type of the parameter variable, or the return type of the containing function respectively should also have a "format"
attribute to avoid the warning.

GCC also warns about function definitions that might be candidates for "format" attributes. Again, these are only possible candidates. GCC
guesses that "format" attributes might be appropriate for any function that calls a function like "vprintf" or "vscanf", but this might not
always be the case, and some functions for which "format" attributes are appropriate may not be detected.

Greetings,

Andres Freund