llvm dev - Dec 2009 - [LLVMdev] source code for llvm

i don't understand the source code : 
static StringMapEntryBase *getTombstoneVal() {
    return (StringMapEntryBase*)-1;
  }     at "include\llvm\adt\stingmaph"  at line 116.
"(StringMapEntryBase*)-1" is it the cast or something other? why there
is a * after class StringMapEntryBase?
thank you ~~
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Cast -1 to a pointer to StringMapEntryBase. -1 is an integer with all
bits being 1.
I have to say if you don't even understand this, just DO NOT try to
rewrite clang in C.

2009/12/20 shines_tao <shines_tao at 126.com>:
>
> i don't understand the source code :
> static StringMapEntryBase *getTombstoneVal() {
>     return (StringMapEntryBase*)-1;
>   }     at "include\llvm\adt\stingmaph"  at line 116.
> "(StringMapEntryBase*)-1" is it the cast or something other? why
there is a
> * after class StringMapEntryBase?
> thank you ~~
>
>
>
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