https://bugs.llvm.org/show_bug.cgi?id=44106
Bug ID: 44106
Summary: clang_getCursorExtent yields invalid range for macro
expansions
Product: clang
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: libclang
Assignee: unassignedclangb...@nondot.org
Reporter: ta...@outlook.com
CC: kli...@google.com, llvm-bugs@lists.llvm.org,
richard-l...@metafoo.co.uk
Currently libclang exposes `CXSourceRange clang_getCursorExtent(CXCursor C)`,
this function
(https://github.com/llvm/llvm-project/blob/master/clang/tools/libclang/CIndex.cpp#L6129)
gets the raw extent and then calls cxloc::translateSourceRange.
cxloc::translateSourceRange
(https://github.com/llvm/llvm-project/blob/master/clang/tools/libclang/CIndex.cpp#L142)
currently has the following comment:
/// Translate a Clang source range into a CIndex source range.
///
/// Clang internally represents ranges where the end location points to the
/// start of the token at the end. However, for external clients it is more
/// useful to have a CXSourceRange be a proper half-open interval. This routine
/// does the appropriate translation.
This comment makes sense and gives an understanding that for an expression
like: `x + 2000` the range used by clang is `x + 2` and it will translate it to
be the full `x + 2000`.
However, the logic the method runs includes some special handling for macro
expansions that ultimately gives you a range of ‘macro start’ to ‘expansion
end’.
This conversion means that for a given macro the range you get back can include
thousands of in-between tokens that are unrelated.
An example of this is the following code where the range of the APPROX_PI
literal in the method starts at the 3 in the macro but ends just before the
semicolon in the method.
That is, the returned range is “Line 1, Column 19” to “Line 5, Column 21”; when
it is expected to be “Line 1, Column 19” to “Line 1, Column 26”.
#define APPROX_PI 3.14159
double getApproxPI()
{
return APPROX_PI;
}
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