http://llvm.org/bugs/show_bug.cgi?id=9799
Summary: MacroExpands callback invoked when the macro should
not be expanded
Product: clang
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: Frontend
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Created an attachment (id=6506)
--> (http://llvm.org/bugs/attachment.cgi?id=6506)
Move the callback invocation after the validity checks
The MacroExpands is invoked when macro FOO(a) is defined, and token FOO is
encountered.
Since FOO isn't a function-like token (that is followed by a parentheses), no
expansion should occur.
I don't think the task of checking this should be left to the callback
receiver.
The macro expansion code (Lex/PPMacroExpansion.cpp,
Preprocessor::HandleMacroExpandedIdentifier) seems to immediately invoke the
callback, before performing any of the checks that might result in the macro
not being expanded.
The actual callback should be delayed as late as possible.
Reading the code, I can see several more situations where the callback should
not be invoked:
* A function-like macro not having the exact number of arguments.
* A macro being a builtin like __LINE__ (Not sure about that. Might be useful)
The attached patch moves the callback invocation to be after the validity
checks. If it is decided that builtin macros are worthy of a callback, the line
can be copied inside the "if (MI->isBuiltinMacro())" condition.
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