[LLVMbugs] [Bug 7409] New: Extra errors after bad typedef

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=7409

           Summary: Extra errors after bad typedef
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Keywords: quality-of-implementation
          Severity: normal
          Priority: P
         Component: C++
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: jyasskin at google.com
                CC: llvmbugs at cs.uiuc.edu, dgregor at apple.com


When we write a typedef with a bad type, and then use the defined name later,
clang treats that name as 'int', which causes extra error spew. Instead, it
should treat the name as an erroneous type and suppress any errors involving
it.


$ cat test.cc
struct BaseReturn {};
template<typename T> struct Foo {
  typedef typename T::foo foo;
  typedef typename foo::bar bar;
};

Foo<long> f;
$ ./clang++ -fsyntax-only test.cc
test.cc:3:20: error: type 'long' cannot be used prior to '::' because it has no
members
  typedef typename T::foo foo;
                   ^
test.cc:7:11: note: in instantiation of template class 'Foo<long>' requested
here
Foo<long> f;
          ^
test.cc:4:20: error: type 'foo' (aka 'int') cannot be used prior to '::'
because it has no members
  typedef typename foo::bar bar;
                   ^
2 errors generated.


Note the "(aka 'int')", which is completely wrong.

A second, more minor problem, is that in the first error, it complains about
'long' but points at 'T', and I've seen a user get confused about what type it
was actually talking about. Using 'T' (aka 'long') might help (but might also
bloat more complex messages).

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