[PATCH] D84322: [AST][RecoveryExpr] Part3: Support dependent conditional operators in C for error recovery.

[Haojian Wu via Phabricator via cfe-commits]

hokein added inline comments.


================
Comment at: clang/test/Sema/error-dependence.c:18
+  // type is required" is not emitted.
+  ptr > f ? ptr : f; // expected-error {{invalid operands to binary expression}}
+}
----------------
sammccall wrote:
> hokein wrote:
> > sammccall wrote:
> > > nit: parens would help me understand here :-)
> > > 
> > > I don't find this example compelling because we should know that "ptr > f" is a boolean.
> > > 
> > > Can we just have `undefined ? ptr : f`, expecting the only diag to be the undeclared ident?
> > > I don't find this example compelling because we should know that "ptr > f" is a boolean.
> > 
> > this is a reasonable impression, but in this case, there is no binary-operator `>` -- operands `ptr`, `f` have different types, and invalid for binary operator, instead we build a recovery-expr.
> > 
> > so the AST looks like (added in the dump-recovery.c test as well)
> > 
> > ```
> >   ConditionalOperator> '<dependent type>' contains-errors
> >     | |-RecoveryExpr  '<dependent type>' contains-errors lvalue
> >     | | |-DeclRefExpr  'int *' lvalue Var 0x8fdb620 'ptr' 'int *'
> >     | | `-DeclRefExpr  'float' lvalue Var 0x8ffd388 'f' 'float'
> >     | |-DeclRefExpr  'int *' lvalue Var 0x8fdb620 'ptr' 'int *'
> >     | `-DeclRefExpr  'float' lvalue Var 0x8ffd388 'f' 'float'
> > ``` 
> > 
> > > Can we just have undefined ? ptr : f, expecting the only diag to be the undeclared ident?
> > 
> > no unfortunately. the whole statement is being dropped (we don't preserve this in C/C++). 
> `undefined() ? ptr : f` then?
oh, yeah. undefined() is not working (undefined function is implicitly treated as `int ()` in C), but `call()` would work.


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https://reviews.llvm.org/D84322