> On Dec 14, 2021, at 4:06 PM, Martin Sebor <mse...@gmail.com> wrote:
>
>>>>>
>>>>
>>>> Dynamically creating the string seems quite cumbersome here, and
>>>> it leaks the allocated block. I wonder if it might be better to
>>>> remove the gmsgid argument from the function and assign it to
>>>> one of the literals based on the other arguments.
>>>>
>>>> Since only one of var and var_name is used, I also wonder if
>>>> the %qs form could be used for both to simplify the overall
>>>> logic. (I.e., get the IDENTIFIER_POINTER string from var and
>>>> use it instead of %qD).
>> Looks like that using “%qs” + get the IDENTIFIER_POINTER string from var did
>> not work very well for the following testing case:
>> 1 /* PR tree-optimization/45083 */
>> 2 /* { dg-do compile } */
>> 3 /* { dg-options "-O2 -Wuninitialized" } */
>> 4
>> 5 struct S { char *a; unsigned b; unsigned c; };
>> 6 extern int foo (const char *);
>> 7 extern void bar (int, int);
>> 8
>> 9 static void
>> 10 baz (void)
>> 11 {
>> 12 struct S cs[1]; /* { dg-message "was declared here" } */
>> 13 switch (cs->b) /* { dg-warning "cs\[^\n\r\]*\\.b\[^\n\r\]*is
>> used uninitialized" } */
>> 14 {
>> 15 case 101:
>> 16 if (foo (cs->a)) /* { dg-warning "cs\[^\n\r\]*\\.a\[^\n\r\]*may
>> be used uninitialized" } */
>> 17 bar (cs->c, cs->b); /* { dg-warning
>> "cs\[^\n\r\]*\\.c\[^\n\r\]*may be used uninitialized" } */
>> 18 }
>> 19 }
>> 20
>> 21 void
>> 22 test (void)
>> 23 {
>> 24 baz ();
>> 25 }
>> For the uninitialized usages at line 13, 16, 17: the IDENTIFIER_POINTER
>> string of var are:
>> cs$0$b, cs$0$a ,cs$0$c
>> However, with %qD, they are printed as cs[0].b, cs[0].a, cs[0].c
>> But with %qs, they are printed as cs$0$b, cs$0$a ,cs$0$c.
>> Looks like that %qD does not simplify print out the IDENTIFIER_POINTER
>> string directly, it specially handle it for some cases.
>> I tried to see how %qD specially handle the strings, but didn’t get it so
>> far.
>> Do you know where the %qD handle this case specially?
>
> In the front end's pretty printer where it handles %D (e.g.,
> for C in c_tree_printer in c/c-objc-common.c). For VARs with
> DECL_HAS_DEBUG_EXPR_P (temp) the code uses DECL_DEBUG_EXPR().
>
> There's also print_generic_expr_to_str(tree) that formats a decl
> or an expression to a dynamically allocated string (the string
> needs to be freed).
Thanks a lot.
This resolved the issue.
Qing
>
> Martin
>
>> Thanks.
>> Qing
>>> Both are good suggestions, I will try to update the code based on this.
>>>
>>> Thanks again.
>>>
>>> Qing
