[cfe-dev] How to find macro arguments?

[Mario Schwalbe]

Hi Manuel,

thanks for the pointer. Meanwhile, I managed to complete the implementation.
You were right. I had to consider the entire range to distinguish the two cases:
The expression `x + 1' (BinaryOperator) has a starting location which is a
macro argument, but its end lies within the macro. For the DeclRefExpr `x' both
locations are considered a macro argument.

ciao,
Mario

On 13.07.15 14:55, Manuel Klimek wrote:
> On Fri, Jul 10, 2015 at 6:56 PM Mario Schwalbe <mario.schwalbe at tu-dresden.de> wrote:
> 
>> Hi all,
>> 
>> I'm trying to familiarize myself with clang and in particular its AST matchers. Therefore, I tried to write some piece of code to determine if an expression has been passed as an argument to a macro:
>> 
>> auto& context = /* ASTContext */ auto& SM = context.getSourceManager(); auto loc = expr.getLocStart();
>> 
>> if (SM.isMacroArgExpansion(loc)) { const auto expLoc = SM.getImmediateExpansionRange(loc).first; const auto name   = Lexer::getImmediateMacroName(expLoc, SM, context.getLangOpts()); if (name == "MACRO") return true; }
>> 
>> Given the following code:
>> 
>> #define MACRO(v)  (v + 1) - 2
>> 
>> int test(int x) { return MACRO(x); }
>> 
>> it also returns true for the expression `x + 1' (BinaryOperator) within the macro expansion, not just the DeclRefExpr `x' itself. Looks like both expressions have the same location (I dumped its internal representation). But why? And how can the 2 cases be distinguished? Or what am I missing here? Thanks in advance for any pointers.
>> 
> 
> I'd expect that for the second case you'd have start and end location of the range in different expansions (which is generally where we'll have to through our hands in the air and go home). You can look at what getFileCharRange / getSourceText in Lexer:: does to make sure a range in a macro is fully on the same expansion level.
> 
> 
>> 
>> ciao, Mario _______________________________________________ cfe-dev mailing list cfe-dev at cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> 
>