simplify mkSkolem naming system: don't use $$

Short summary: By default NODEID is appeneded, just continue doing what you
were, just don't add the _$$ at the end.

Long summary:

Before this commit there were four (yes!) ways to specify the names for new
skolems, which result in names as given below

1) mkSkolem("name", ..., SKOLEM_FLAG_DEFAULT)  -> "name_NODEID"
2) mkSkolem("name", ..., SKOLEM_EXACT_NAME)  -> "name"
3) mkSkolem("name_$$", ..., SKOLEM_FLAG_DEFAULT) -> "name_NODEID"
4) mkSkolem("na_$$_me", ..., SKOLEM_FLAG_DEFAULT) -> "na_NODEID_me"

After this commit, only 1) and 2) stay.

90% usage is of 1) or 3), which results in exact same behavior (and
looking at the source code it doesn't look like everyone realized that
the _$$ is just redundant).

Almost no one used 4), which is the only reason to even have $$. Post this
commit if you really want a number in the middle, manually construct the
name and use the SKOLEM_EXACT_NAME flag.

1 files changed, 6 insertions, 7 deletions

diff --git a/src/expr/node_manager.h b/src/expr/node_manager.h
index 15c49efd8..f533d3ab9 100644
--- a/src/expr/node_manager.h
+++ b/src/expr/node_manager.h
@@ -424,12 +424,11 @@ public:
   /**
    * Create a skolem constant with the given name, type, and comment.
    *
-   * @param name the name of the new skolem variable.  This name can
-   * contain the special character sequence "$$", in which case the
-   * $$ is replaced with the Node ID.  That way a family of skolem
-   * variables can be made with unique identifiers, used in dump,
-   * tracing, and debugging output.  By convention, you should probably
-   * call mkSkolem() with a custom name appended with "_$$".
+   * @param prefix the name of the new skolem variable is the prefix
+   * appended with the Node ID.  This way a family of skolem variables
+   * can be made with unique identifiers, used in dump, tracing, and
+   * debugging output.  Use SKOLEM_EXECT_NAME flag if you don't want
+   * Node ID appended and use prefix as the name.
    *
    * @param type the type of the skolem variable to create
    *
@@ -440,7 +439,7 @@ public:
    * @param flags an optional mask of bits from SkolemFlags to control
    * mkSkolem() behavior
    */
-  Node mkSkolem(const std::string& name, const TypeNode& type,
+  Node mkSkolem(const std::string& prefix, const TypeNode& type,
                 const std::string& comment = "", int flags = SKOLEM_DEFAULT);
 
   /** Create a instantiation constant with the given type. */