On Tue, 20 Jan 2026, Richard Biener wrote:
> The following avoids a diagnostic difference between -g0 and -g2 related
> to artificial variables created by SRA.
>
> This causes
>
> +FAIL: gfortran.dg/goacc/modules.f95 -O at line 22 (test for warnings,
> line
> 20)
> +XPASS: gfortran.dg/goacc/modules.f95 -O TODO at line 21 (test for
> bogus mess
> ages, line 20)
>
> That's
>
> !$ACC DATA PRESENT(arr) COPY(sum)
> !$ACC PARALLEL LOOP REDUCTION(+ : sum)
> ! { dg-bogus {'sum\.[0-9]+' is used uninitialized} TODO { xfail *-*-* }
> .-1 }
> ! { dg-note {'sum\.[0-9]+' was declared here} {} { target *-*-* } .-2
> }
> DO k=y_min,y_max
>
> and a whole load of similar fallout in libgomp.oacc-fortran. It
> probably does not fix whatever issue is present there (but it avoids
> the diagnostic). I've refrained from updating the testcases but
> will happily do if the patch is approved.
>
> Otherwise bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> OK with the goacc testcases adjusted? OK to simply remove the
> dg-note line or should I XFAIL it?
Ping. Any opinion?
> Thanks,
> Richard.
>
> PR tree-optimization/123651
> * tree-ssa-uninit.cc (warn_uninit): Treat DECL_ARTIFICIAL
> var as if it were not present.
>
> * g++.dg/warn/Wuninitialized-pr123651.C: New testcase.
> ---
> .../g++.dg/warn/Wuninitialized-pr123651.C | 29 +++++++++++++++++++
> gcc/tree-ssa-uninit.cc | 17 +++++++++--
> 2 files changed, 43 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/warn/Wuninitialized-pr123651.C
>
> diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-pr123651.C
> b/gcc/testsuite/g++.dg/warn/Wuninitialized-pr123651.C
> new file mode 100644
> index 00000000000..603009a475b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-pr123651.C
> @@ -0,0 +1,29 @@
> +// { dg-do compile }
> +// { dg-options "-O2 -g -Wuninitialized" }
> +
> +void use(int *);
> +
> +struct Count {
> + int *p;
> + // We emitted the diagnostic only with -g and for an artificial
> + // SR.5 variable which would be not so useful in case of a call
> + // with multiple arguments.
> + // So an XFAILed expected diagnostic for the member 'p' would be
> + // what's truly wanted.
> + ~Count() { use(p); } // { dg-bogus "uninitialized" }
> + Count(Count &) {}
> +};
> +
> +struct Ptr {
> + int x;
> + Count c;
> +};
> +
> +void sink(int, Ptr) {}
> +
> +struct Holder {
> + template <typename T> void put(T v) { sink(v, ref_); }
> + Ptr ref_;
> +};
> +
> +void test(Holder h) { h.put(0); }
> diff --git a/gcc/tree-ssa-uninit.cc b/gcc/tree-ssa-uninit.cc
> index 284445b20f8..54517ffc116 100644
> --- a/gcc/tree-ssa-uninit.cc
> +++ b/gcc/tree-ssa-uninit.cc
> @@ -273,6 +273,17 @@ warn_uninit (opt_code opt, tree t, tree var, gimple
> *context,
> }
> }
>
> + /* Avoid diagnosing artificial decls - whether those are present or
> + not can depend on debug info level. But make sure to diagnose
> + decls that are replacements for user variables as created by SRA. */
> + tree orig_var = var;
> + if (var && DECL_ARTIFICIAL (var) && !DECL_HAS_DEBUG_EXPR_P (var)
> + /* ??? Fortran expects the artificial __result_<fn> to be
> + diagnosed about which isn't a RESULT_DECL, so key on
> + DECL_IGNORED_P. */
> + && DECL_IGNORED_P (var))
> + var = NULL_TREE;
> +
> if (var == NULL_TREE && var_name_str == NULL)
> return;
>
> @@ -281,7 +292,7 @@ warn_uninit (opt_code opt, tree t, tree var, gimple
> *context,
> if (((warning_suppressed_p (context, OPT_Wuninitialized)
> || (gimple_assign_single_p (context)
> && get_no_uninit_warning (gimple_assign_rhs1 (context)))))
> - || (var && get_no_uninit_warning (var))
> + || (orig_var && get_no_uninit_warning (orig_var))
> || (var_name_str
> && warning_suppressed_p (var_def_stmt, OPT_Wuninitialized)))
> return;
> @@ -322,8 +333,8 @@ warn_uninit (opt_code opt, tree t, tree var, gimple
> *context,
> }
>
> /* Avoid subsequent warnings for reads of the same variable again. */
> - if (var)
> - suppress_warning (var, opt);
> + if (orig_var)
> + suppress_warning (orig_var, opt);
> else if (var_name_str)
> suppress_warning (var_def_stmt, opt);
>
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
