[LLVMdev] Improving cast<> failure messages.

[James Molloy]

Hi,

> This would have to introduce a dependency in llvm/Support/Casting.h on 
> some library for string concatenation; preferably <string> but a 
> lower-level interface could be used it someone objects (or it could be 
> done manually, but that seems horrible).

Wouldn't StringRef make more sense?

Cheers,

James

> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> On Behalf Of Sean Hunt
> Sent: 22 June 2011 03:55
> To: llvmdev at cs.uiuc.edu
> Subject: [LLVMdev] Improving cast<> failure messages.
> 
> Would anyone object to an attempt to improve cast<> error messages by
> outputting the expected type and the type received?
> 
> The interface I'm thinking of is to use ADL to do visitor-style lookup,
> so we don't need to change every client. In particular, for clients in
> clang, we can just create these functions implicitly from our
> TableGen-generated files. I'm not sure about clients in LLVM since I
> don't do much work there.
> 
> This would have to introduce a dependency in llvm/Support/Casting.h on
> some library for string concatenation; preferably <string> but a
> lower-level interface could be used it someone objects (or it could be
> done manually, but that seems horrible).
> 
> An example of what this would be like is:
> 
> // Before cast<> in llvm/Support/Casting.h
> const char *DebugTypeName(void*) {
> }
> 
> // In the header for the type at some reasonable point before cast<> is
> // instatiated for that type
> const char *DebugTypeName(Foo*) {
>    return "Foo";
> }
> 
> The pointer is only for ADL purposes and will always be 0.
> 
> Sean
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