rsmith added inline comments.
================
Comment at: clang/lib/Parse/ParseDeclCXX.cpp:1032
+ // the typename-specifier in a function-style cast expression may
+ // be 'auto' since C++2b
Diag(Tok.getLocation(),
----------------
Quuxplusone wrote:
> rsmith wrote:
> > Nice catch :)
> I see zero hits for `git grep 'decltype[(]auto[^)] clang/`. So it seems this
> corner of the grammar has been missing any tests for a long time, but I hope
> this PR will add some.
> ```
> decltype(auto*) i = 42; // should be a syntax error
> decltype(auto(42)) i = 42; // should be OK
> decltype(auto()) i = 42; // should be a syntax error
> ```
> Right now I don't see any tests for this stuff in this PR either. So it needs
> some.
Some of this is tested in the new file
test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.auto.deduct/p2.cpp (you might need
to expand it manually; full-page search for `decltype(auto(` might otherwise
not find it). It looks like we are missing tests for things like
`decltype(auto*)`. It's not obvious to me what diagnostic would be most useful
if `decltype(auto` is not followed by `)`, `(`, or `{`, but my guess is that
"expected `)`" pointing at the `*`, rather than an error on the `auto` token,
would be the least surprising. So maybe this should be
```
if (Tok.is(tok::kw_auto) && NextToken().isNot(tok::l_paren, tok::l_brace)) {
```
?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D113393/new/
https://reviews.llvm.org/D113393
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