[cfe-dev] Clang 3.3 assertion failure for local extern declarations of variables with names matching function parameters

[David Blaikie]

On Mon, Aug 5, 2013 at 11:40 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> The code is ill-formed. We're supposed to catch this due to
> [basic.scope.block]p2: "A parameter name shall not be redeclared in the
> outermost block of the function definition" but our check for that seems to
> be broken or missing.

Broken - I believe I was the last one to muck with this in an effort
to have it catch the same case, but with function-try blocks. I may've
broken something while I was there, or perhaps this case was always
broken.

Simple case working:

$ cat scope.cpp
void func(int i) {
  int i;
}
blaikie at blaikie:~/dev/scratch$ clang++-tot scope.cpp
scope.cpp:2:7: error: redefinition of 'i'
  int i;
      ^
scope.cpp:1:15: note: previous definition is here
void func(int i) {
              ^
1 error generated.

I think that's Clang's implementation of that rule, at least - though
I could be wrong.

>
> On Mon, Aug 5, 2013 at 8:25 PM, Tom Honermann <thonermann at coverity.com>
> wrote:
>>
>> Clang 3.3, when compiled with assertions enabled, fails an assertion for
>> the following test case.  I believe this code is ill-formed, but at least
>> some versions of gcc accept this test case (I tested 4.6.3 and 4.8.0).
>> Clang 3.2 accepts this test case as well.
>>
>> I filed a bug report for the assertion failure [1], but thought it would
>> be good to clarify expected behavior on the mailing list.
>>
>> $ cat t.cpp
>> struct S;
>> void f(S *s) {
>>     extern S *s;
>>     s;
>> }
>>
>> $ clang --version
>> clang version 3.3 (tags/RELEASE_33/final)
>> Target: x86_64-unknown-linux-gnu
>> Thread model: posix
>>
>> $ clang -c t.cpp
>> clang: llvm-3.3/tools/clang/lib/AST/Decl.cpp:932: void
>> clang::NamedDecl::verifyLinkage() const: Assertion `!D || D->CachedLinkage
>> == CachedLinkage' failed.
>>
>> [1]: http://llvm.org/bugs/show_bug.cgi?id=16804
>>
>> Tom.
>>
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>
>
>
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