https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107751
Bug ID: 107751
Summary: [11/12 regression] False positive
-Wmaybe-uninitialized
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: alvinhochun at gmail dot com
Target Milestone: ---
This test case produces false-positive -Wmaybe-uninitialized warnings:
===
template <class T1, class T2>
bool std_equal(T1* a1, T1* a2, T2* b1);
template <class T1, class T2>
bool std_equal(T1* a1, T1* a2, T2* b1, T2* b2);
template <class T1, class T2>
void f() {
int a[3] = {1, 2, 3};
T1* x = a;
T2* y = a;
std_equal(x, x + 3, y);
std_equal(y, y + 3, x);
std_equal(x, x + 3, y, y + 3);
std_equal(y, y + 3, x, x + 3);
}
int main(int, char**) {
f<int, int>();
f<int, const int>();
f<int, volatile int>();
f<int, const volatile int>();
f<const int, const int>();
f<const int, volatile int>();
f<const int, const volatile int>();
f<volatile int, volatile int>();
f<volatile int, const volatile int>();
f<const volatile int, const volatile int>();
return 0;
}
===
Output:
===
<source>: In function 'void f() [with T1 = const int; T2 = const int]':
<source>:12:14: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
12 | std_equal(x, x + 3, y);
| ~~~~~~~~~^~~~~~~~~~~~~
<source>:2:6: note: by argument 2 of type 'const int*' to 'bool std_equal(T1*,
T1*, T2*) [with T1 = const int; T2 = const int]' declared here
2 | bool std_equal(T1* a1, T1* a2, T2* b1);
| ^~~~~~~~~
<source>:9:9: note: 'a' declared here
9 | int a[3] = {1, 2, 3};
| ^
<source>: In function 'void f() [with T1 = const int; T2 = volatile int]':
<source>:12:14: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
12 | std_equal(x, x + 3, y);
| ~~~~~~~~~^~~~~~~~~~~~~
<source>:2:6: note: by argument 2 of type 'const int*' to 'bool std_equal(T1*,
T1*, T2*) [with T1 = const int; T2 = volatile int]' declared here
2 | bool std_equal(T1* a1, T1* a2, T2* b1);
| ^~~~~~~~~
<source>:9:9: note: 'a' declared here
9 | int a[3] = {1, 2, 3};
| ^
<source>: In function 'void f() [with T1 = const int; T2 = const volatile
int]':
<source>:12:14: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
12 | std_equal(x, x + 3, y);
| ~~~~~~~~~^~~~~~~~~~~~~
<source>:2:6: note: by argument 2 of type 'const int*' to 'bool std_equal(T1*,
T1*, T2*) [with T1 = const int; T2 = const volatile int]' declared here
2 | bool std_equal(T1* a1, T1* a2, T2* b1);
| ^~~~~~~~~
<source>:9:9: note: 'a' declared here
9 | int a[3] = {1, 2, 3};
| ^
<source>: In function 'void f() [with T1 = const volatile int; T2 = const
volatile int]':
<source>:12:14: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
12 | std_equal(x, x + 3, y);
| ~~~~~~~~~^~~~~~~~~~~~~
<source>:2:6: note: by argument 2 of type 'const volatile int*' to 'bool
std_equal(T1*, T1*, T2*) [with T1 = const volatile int; T2 = const volatile
int]' declared here
2 | bool std_equal(T1* a1, T1* a2, T2* b1);
| ^~~~~~~~~
<source>:9:9: note: 'a' declared here
9 | int a[3] = {1, 2, 3};
| ^
===
Compiler Explorer: https://godbolt.org/z/KsM6herr9
