[cfe-dev] Help with replacements on macros

[Manuel Klimek via cfe-dev]

On Thu, Jun 30, 2016 at 7:02 AM scott constable via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> Hi All,
>
> I have an AST matcher which has successfully matched all "if" statements
> in a large program:
>
> StatementMatcher CondMatcher =
> ifStmt(hasCondition(expr().bind("condition")));
>
> My goal is to use libtooling replacements to refactor all "if" conditions
> <cond> into my_func(<cond>). For instance,
>
> if (true) { ... }
>
> should refactor to
>
> if (my_func(true)) { ... }
>
> The only time I run into trouble is when I try to refactor complex macros.
> For instance, take the following code:
>
> #define GUARD2 GUARD1(999)
> #define GUARD1(X) if (1 | X) { return 11; }
>
> int main() {
>   GUARD2
>   return 0;
> }
>
> My AST matcher successfully grabs the expanded if statement's condition.
> To perform my replacement, I would like to obtain the following source
> locations:
>
> #define GUARD2 GUARD1(999)
> #define GUARD1(X) if (<LBegin>1 | X<LEnd>) { return 11; }
>
> int main() {
>   GUARD2
>   return 0;
> }
>
> but if I do something like
>
> SourceLocation LBegin =
> MySourceManager.getSpellingLoc(Condition->getBeginLoc());
> SourceLocation LEnd =
> MySourceManager.getSpellingLoc(Condition->getEndLoc());
> LEnd = Lexer::getLocForEndOfToken(LEnd, 0, MySourceManager, opts);
>
> then the source locations are as follows:
>
> #define GUARD2 GUARD1(999<LEnd>)
> #define GUARD1(X) if (<LBegin>1 | X) { return 11; }
>
> int main() {
>   GUARD2
>   return 0;
> }
>
> And thus the replacements turn out as
>
> 1 #define GUARD2 GUARD1(999))
> 2 #define GUARD1(X) if (my_func(1 | X) { return 11; }
> 3
> 4 int main() {
> 5   GUARD2
> 6   return 0;
> 7 }
>
> which is incorrect. Note the extra parenthesis in line 1, and missing
> parenthesis in line 2. Any help at all would be very much appreciated.
>

That's what Lexer::makeFileCharRange solves - for a given range, it will
give you the range on the same macro expansion level, if such a range
exists.


>
> Thanks in advance,
>
> Scott Constable
> _______________________________________________
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> cfe-dev at lists.llvm.org
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>
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