https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90740
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |ice-on-valid-code,
| |wrong-code
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-06-04
Known to work| |8.3.0
Target Milestone|--- |9.2
Summary|VLA with lamba causes an |[9/10 Regression] VLA with
|incorrect unitialized in |lamba causes an incorrect
|this function warning |unitialized in this
| |function warning
Ever confirmed|0 |1
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, plain 9.1.0 ICEs for me at -O0
t.C: In lambda function:
t.C:14:59: warning: fold-expressions only available with ‘-std=c++17’ or
‘-std=gnu++17’
14 | bar([&buf, &out...](auto&... column) { (doit(column), ...); },
out...);
| ^~~
during RTL pass: expand
t.C: In lambda function:
t.C:14:9: internal compiler error: in expand_expr_real_1, at expr.c:10012
14 | bar([&buf, &out...](auto&... column) { (doit(column), ...); },
out...);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
v0x5c58c8 expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier, rtx_def**, bool)
Confirmed with -O2 -Wall. Note with checking enabled on the branch we ICE
also with -O2 -Wall:
t.C: In instantiation of ‘read(Vs& ...) [with Vs = {int}]::<lambda(auto:1&
...)> [with auto:1 = {int}]’:
t.C:3:6: required from ‘void bar(T, U ...) [with T = read(Vs& ...) [with Vs =
{int}]::<lambda(auto:1& ...)>; U = {int}]’
t.C:14:8: required from ‘void read(Vs& ...) [with Vs = {int}]’
t.C:19:12: required from here
t.C:13:10: internal compiler error: in tsubst_copy, at cp/pt.c:16185
13 | char buf[SIZE];
| ^~~
0xafa361 tsubst_copy
/space/rguenther/src/svn/gcc-9-branch/gcc/cp/pt.c:16185
0xb0df7b tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
/space/rguenther/src/svn/gcc-9-branch/gcc/cp/pt.c:19612
default:
/* We shouldn't get here, but keep going if !flag_checking. */
if (flag_checking)
gcc_unreachable ();
and that likely is the reason for the breakage. The gimple dump already
shows:
read(Vs& ...) [with Vs = {int}]::<lambda(auto:1& ...)>::operator()<int> (const
struct __lambda1 * const this, int & column#0)
{
sizetype D.2163;
bitsizetype D.2164;
sizetype D.2165;
int & out#0 [value-expr: ((const struct __lambda1 *) this)->__out#0];
char[0:D.2163] & buf [value-expr: ((const struct __lambda1 *) this)->__buf];
_1 = D.2153 + -1;
D.2163 = (sizetype) _1;
_3 = (sizetype) D.2153;
_4 = (bitsizetype) _3;
D.2164 = _4 * 8;
D.2165 = (sizetype) D.2153;
{
_7 = *column#0;
doit<int> (_7);
}
}
see how D.2153 is never initialized, so this is also wrong-code with
-fno-checking (and we shouldn't have this kind of continue-if-not-checking...).
ICEs are better than silent wrong-code.
We don't handle
SAVE_EXPR <(ssizetype) SIZE + -1>
not sure why.
