False positive for cppcoreguidelines-init-variables in range based for loop in template function

[pgerell]

Bugzilla Link	44746
Resolution	FIXED
Resolved on	Feb 10, 2020 05:20
Version	unspecified
OS	Linux
Blocks	#43900
CC	@zmodem,@pgerell
Fixed by commit(s)	efcd09c

Extended Description

clang-tidy-10 as of 2020-01-31 gives the following false positive

====== test.cpp ======
template
void f(RANGE r) {
for (char c : r) {

}
}

$ clang-tidy test.cpp --checks='cppcoreguidelines*'
test.cpp:3:13: warning: variable 'c' is not initialized [cppcoreguidelines-init-variables]
for (char c : r) {
^
= 0

Also reproducible on trunk:
https://godbolt.org/z/s_bCSi

[llvmbot]

This is an odd case, for some reason this code doesn't trigger the warning

==========================
template
void g(std::vector r) {
for (T c : r) {
}
}

https://godbolt.org/z/L9NdQx

Anyway here is a fix, just disable the check when we detect the var decl is the loop variable of a for range statement.

https://reviews.llvm.org/D73843

[llvmbot]

Fixed in efcd09c

[pgerell]

Thank you.
I have verified that this solves my original problem.
Will this be cherry-picked to the 10.x branch?

[llvmbot]

I'll add it as a release blocker but I'm not entirely sure it should go in there. I'll let Hans have the final verdict on this matter

[zmodem]

I'll add it as a release blocker but I'm not entirely sure it should go in
there. I'll let Hans have the final verdict on this matter

Sounds good to me. Cherry-picked as 84cda4c