[cfe-dev] match OffsetOfExpr

[Nathan James via cfe-dev]

On Fri, 2020-08-14 at 10:01 -0400, Aaron Ballman via cfe-dev wrote:
> On Fri, Aug 14, 2020 at 9:48 AM Billy Araujo <billyaraujo at gmail.com>
> wrote:
> > Just an update on this:
> > This matcher works fine in Linux.
> > When I said it didn't work, that was on Windows.
> 
> An OffsetOfExpr is only generated when parsing __builtin_offsetof, so
> my guess is that the macro for offsetof is expanding to address
> arithmetic for you rather than a call to __builtin_offsetof.
> 
> ~Aaron
> 
In cases where offsetof expands to the arithmetic, this will not match.
That is probably reason in itself to not make a matcher for this.
It would just result in confusing users wondering why offsetOfExpr
isn't matching offsetof in their source code.

~Nathan
> > 
> > On Fri, Aug 14, 2020 at 10:35 AM Billy Araujo <
> > billyaraujo at gmail.com> wrote:
> > > Hi,
> > > 
> > > I don't know how it should be matched, using classOf, dyn_cast,
> > > or isa.
> > > 
> > > I tried:
> > > 
> > > namespace
> > > {
> > >     AST_MATCHER(clang::Stmt, isOffsetOf) { return
> > > clang::isa<clang::OffsetOfExpr>(&Node); }
> > > }
> > > 
> > > and still doesn't match.
> > > 
> > > 
> > > On Wed, Aug 12, 2020 at 7:37 PM Aaron Ballman <
> > > aaron at aaronballman.com> wrote:
> > > > On Wed, Aug 12, 2020 at 1:52 PM Billy Araujo via cfe-dev
> > > > <cfe-dev at lists.llvm.org> wrote:
> > > > > Anyone know how to match OffsetOfExpr?
> > > > > 
> > > > > > -FunctionDecl 0x2484fff0298 <line:9:1, line:12:1> line:9:13
> > > > > > used f1 'void ()' static
> > > > > > `-CompoundStmt 0x2484fff03c8 <line:10:1, line:12:1>
> > > > > >   `-OffsetOfExpr 0x2484fff0390 <C:\Program
> > > > > > Files\LLVM\lib\clang\10.0.0\include\stddef.h:104:24,
> > > > > > col:47> 'unsigned long long'
> > > > > 
> > > > > In clang-query if I type: m offsetOfExpr() is says: matcher
> > > > > not found.
> > > > 
> > > > We don't currently expose a matcher for it, so that's why it's
> > > > not
> > > > found. It wouldn't be difficult to add a matcher for it,
> > > > however (feel
> > > > free to add me as a review if you decide to author a patch for
> > > > this).
> > > > 
> > > > ~Aaron
> > > > 
> > > > > 
> > > > > _______________________________________________
> > > > > cfe-dev mailing list
> > > > > cfe-dev at lists.llvm.org
> > > > > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev