zequanwu added inline comments.
================
Comment at: clang/lib/Sema/AnalysisBasedWarnings.cpp:1518
UsesMap uses;
+ UsesMap constRefUses;
----------------
rnk wrote:
> If possible, it would be nice to avoid having a second map.
I use second map to let the new warning be orthogonal to existing warnings.
That means when we have both `-Wuninitialized` and
`-Wno-uninitialized-const-reference`, the old test cases about uninitialized
variables should all passed. Otherwise, I need to somehow detect the presence
of `-Wno-uninitialized-const-reference`, which I don't see a way to do that.
Consider this code if we have only one map:
```
void consume_const_ref(const int &n);
int test_const_ref() {
int n;
consume_const_ref(n);
return n;
}
```
No matter if the flag`-Wno-uninitialized-const-reference` is present or not, we
still need to add `n` in `consume_const_ref(n);` to `uses` map and then let
`S.Diag` to decide to diagnose it or not depend on the presence of
`-Wno-uninitialized-const-reference`. If the flag is given, `S.Diag` will just
ignore the warning, but uninit var warning will diagnose if `Use.getKind()`
returns `Always` in
https://github.com/llvm/llvm-project/blob/master/clang/lib/Sema/AnalysisBasedWarnings.cpp#L814
. That is not desired. Since the original behavior is to ignore the `n` in
`consume_const_ref(n);` by not adding it to the `uses` map.
If there is a way to detect the presence of
`-Wno-uninitialized-const-reference` or to know if `Sema::Diag(SourceLocation
Loc, unsigned DiagID)` actually diagnosed a warning, the use of second map can
be avoid.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D79895/new/
https://reviews.llvm.org/D79895
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