C++
clang HEAD 12.0.0 (https://github.com/llvm/llvm-project.git 035396197a5f129c5ec42e9e46a85c32fa1c1b84)
$ clang++ prog.cc -Wall -Wextra -I/opt/wandbox/boost-1.73.0/clang-head/include -std=c++2a -pedantic -Wundefprog.cc:15:9: warning: variable 't' is uninitialized when used here [-Wuninitialized]
s = t + u + v; // C4700: t, u, v used before initialization
^
prog.cc:13:13: note: initialize the variable 't' to silence this warning
int s, t, u, v; // Danger, uninitialized variables
^
= 0
prog.cc:15:13: warning: variable 'u' is uninitialized when used here [-Wuninitialized]
s = t + u + v; // C4700: t, u, v used before initialization
^
prog.cc:13:16: note: initialize the variable 'u' to silence this warning
int s, t, u, v; // Danger, uninitialized variables
^
= 0
prog.cc:15:17: warning: variable 'v' is uninitialized when used here [-Wuninitialized]
s = t + u + v; // C4700: t, u, v used before initialization
^
prog.cc:13:19: note: initialize the variable 'v' to silence this warning
int s, t, u, v; // Danger, uninitialized variables
^
= 0
3 warnings generated.
Value in s: -1385823988
Value in w: 42