https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85159
Bug ID: 85159
Summary: if constexpr error about goto
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: drepper.fsp+rhbz at gmail dot com
Target Milestone: ---
This is actually something I deliberate used if constexpr for to avoid warnings
but gcc creates a new kind of error. Take this silly code:
template<bool B>
int foo(int a, int b)
{
if constexpr (B) {
a += 1;
goto L;
} else
b += 1;
if constexpr (B) {
L:
return a - b;
} else
return b - a;
}
int main()
{
return foo<false>(3, 4);
}
The definition and use of the label are in if constexpr blocks controlled by
the same condition. gcc issues this warning (this is mainline gcc as of last
week or so):
u.cc: In function ‘int foo(int, int)’:
u.cc:10:3: error: jump to label ‘L’
L:
^
u.cc:6:10: note: from here
goto L;
^
u.cc:9:16: note: enters constexpr if statement
if constexpr (B) {
^
I think gcc should look at the block conditions and avoid the error.
