Re: [Cocci] Analysis for Linux source files

[Julia Lawall]

Attached is a patch.  The line numbers may be off, but it should apply to
the latest version.  It causes a match failure for the following semantic
patch:

@r@
type T;
identifier x;
position p;
@@

T@p x;

@script:python@
T << r.T;
@@

print "before"
print T
print "after"

when applied to the following code:

int main () {
  register x;
  return 0;
}

The type metavariable would have been matched to the implicit "int", but
this implicit int doesn't have a position, so the match of the position
variable fails.  On the other hand, there is no more crash.

julia
diff --git a/engine/cocci_vs_c.ml b/engine/cocci_vs_c.ml
index 4d12515..26a479c 100644
--- a/engine/cocci_vs_c.ml
+++ b/engine/cocci_vs_c.ml
@@ -2820,7 +2820,13 @@ and (fullTypebis: (A.typeC, Ast_c.fullType) matcher) =
        match ty with
          B.NoType -> false
        | _ -> true in
-      if type_present
+      let position_required_but_unavailable =
+       match A.get_pos_var ida with
+         [] -> false
+       | _ ->
+           let (tyq, (ty, tyii)) = typb in
+           List.for_all Ast_c.is_fake tyii in
+      if type_present && not position_required_but_unavailable
       then
        let max_min _ =
          Lib_parsing_c.lin_col_by_pos (Lib_parsing_c.ii_of_type typb) in

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