[cfe-dev] how to implement "statement P is followed by statement Q" matcher?

[Richard]

I recently had to go through a bit of manual coding in order to match
this in clang-tidy:

if (expr)
  return true;
return false;

What I really wanted was to be able to write something like this:

compoundStmt(
  isFollowedBy(
    ifStmt(
      hasThen(returnStmt(has(booleanLiteral(equals(true))))),
      unless(hasElse(anything()))),
    returnStmt(has(booleanLiteral(equals(false))))
  )
)

There are matchers that tell me if a compound statment has *any*
substatement, but there aren't any matchers that allow me to specify
the order in which related statements appear within a compound
statement.

(Aside: note the heavy-handed use of the has() matcher above on a
returnStmt.  There's no way to access the return expression directly
on a returnStmt.)

In my case I really needed an "isFollowedBy" style matcher, because I
didn't want to match this:

if (expr)
  return true;
doSomethingElse();
return false;

However, I can easily see people wanting to match a compound statement
that has two related statements in a particular order, but possibly
with other statements in between.

I'm interested in hearing thoughts on such a squential matcher
"isFollowedBy" and how I would implement such a thing.  So far my
forays into matchers have been really small and I haven't yet learned
the subtleties or the full vocabulary of the matcher macros.


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