[cfe-dev] AST Matcher matches InitListExpr child twice

[Ben Liblit via cfe-dev]

Consider the following C++11 (or later) code fragment, which uses an 
initialization list that contains a function call:

	int f();
	int i {f()};

The AST for that initialization list consists of an InitListExpr with a 
single CallExpr child:

	InitListExpr 0x2df2b80 'int'
	`-CallExpr 0x2df2b10 'int'
	  `-ImplicitCastExpr 0x2df2af8 ...
	    `-DeclRefExpr 0x2df2aa0 ...

If I use the Clang AST Matcher API to match on InitListExpr, then I get 
one match as expected.  However, if I match on CallExpr, then the single 
CallExpr in the above AST is matched *twice*.  Anything below that 
CallExpr node is also matched twice; for example, I'd get two matches 
for the DeclRefExpr if that's what my AST Matcher were looking for. 
This is definitely a problem for my code, and would seem to be a bug in 
general.  Surely that's not the intended behavior, is it?

Attached below is a small test program, "visit.cc", that matches and 
dumps out InitListExpr and CallExpr nodes in the AST.  Running this on 
my above example clearly shows that only one InitListExpr is matched, 
but a single CallExpr (at a single memory address) is matched *twice*.

Should I file this glitch as a Clang bug report rather than describing 
it on this mailing list?  Is there a reasonable workaround until this 
bug can be properly fixed?

Thanks,
Ben
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