http://llvm.org/bugs/show_bug.cgi?id=3927
Summary: Clang expands the same macro differently depending on
its identifier
Product: clang
Version: unspecified
Platform: PC
OS/Version: NetBSD
Status: NEW
Severity: normal
Priority: P2
Component: preprocessor
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
I submitted this before, but it was abruptly closed with "resubmit".
Anyway...last time.
Observe the output of -E for the following; both lines output should be the
same:
#define f(x) h(x
#define for(x) h(x // for is the same macro as f .....
#define h(x) x(void)
extern int f(f));
extern int for(for)); // but it exapnds differently....
The problem is rooted in Clang's representation of "is this token an
identifier?". It is tempting to answer that question by testing the token
type, because this is the correct decision for all token types but identifiers.
Identifiers are treated differently and the correct test for identifiers is
only to test for identifier info being non-null (I believe).
This non-obvious situation led to this bug; which I noticed perusing the source
code (rather than dreaming up obscene tests, in case the reader wondered).
I suggest all of CPP is audited for this mistake, assuming this design decision
(efficiency perhaps?) is still deemed the right one.
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