Hi,
Richard Smith suggested that I try to improve the diagnostic emitted when
Clang encounters certain kinds of invalid C+11 ranged-based for loops.
When a pointer to a container is used as the range in a range-based for,
> Clang's diagnostic is not awesome:
>
> struct S { int *begin(); int *end(); };
>> void f(S *p) {
>> for (auto i : p) {}
>> }
>> tmp.cpp:3:15: error: use of undeclared identifier 'begin'
>> for (auto i : p) {} }
>> ^
>> tmp.cpp:3:15: note: range has type 'S *'
>
>
> We should do better than that, and suggest inserting the missing '*'.
>
This patch replaces the errors complaining about undeclared identifiers
with an error specific to ranged-for loops, along with an explanatory note.
I also updated the existing test cases to reflect the change. For example,
the above code now generates this:
test.cpp:3:15: error: invalid range expression of type 'S *'
> for (auto i : p) {}
> ^ ~
> test.cpp:3:16: note: range expression is of type 'S *'; did you
> mean to dereference it with '*'?
> for (auto i : p) {}
> ^
> *
> test.cpp:3:14: note: no viable 'end' function for range of type
> 'S *'
> for (auto i : p) {}
I hope that this is helpful, and comments are always welcome.
-Sam
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