+++ b/src/V3Inst.cpp
+    std::map<string,AstVar*> m_seenInterfaceVarp;

A later comment will get rid of this, but next time please add and use something like:

typedef std::map<string,AstVar*> SeenIfNameMap;


+++ b/src/V3Inst.cpp
@@ -217,6 +244,29 @@ private:
+       } else if(AstArraySel *arrselp = nodep->exprp()->castArraySel()) {
+           if (AstUnpackArrayDType *arrp = arrselp->lhsp()->dtypep()->castUnpackArrayDType()) {
+               if (!arrp->subDTypep()->castIfaceRefDType())
+                   return;
+
+               AstConst *constp = arrselp->rhsp()->castConst();
+               if (!constp) {
+                   nodep->v3error("Unsupported: Non-constant index when passing interface to module");

Need a return or something here, otherwise the next line is going to core dump.

+               }
+               string index = AstNode::encodeNumber(constp->toSInt());
+               AstVarRef *varrefp = arrselp->lhsp()->castVarRef();
+
+               AstVarRef *newp = new AstVarRef(nodep->fileline(),varrefp->name () + "__BRA__" + index  + "__KET__", false);
+               newp->dtypep(arrp->subDTypep());
+               //Wilson: I'm looking for a way to do this in a better way. My original attempt was to call V3LinkDot again after the V3Inst stage
+               //But the Ast has progressed too far and V3LinkDot messes it up (notably the t_lint_ifdepth_bad.pl test fails
+               //because it thinks the variable is defined twice.
+               // Also, this is not setting newp->packagep(). I hope you can give advice on how to do this properly.

Right, in general outside LinkDot code can't ever connect using a name
lookup. LinkDot also can't be called elsewhere. I think however you could
make a VarXRef, which requires a link to any element of the interface
"newp->varp(varrefp->varp())", then the name will get resolved by V3LinkDot
later.

For newp, the variable you're referencing is in the same scope as varrefp,
right, so just "newp->packagep(verrefp->packagep())".  Otherwise you'd need
to find the package to which the variable you reference lives, perhaps by
storing that information in a earlier visitor pass.



+++ b/src/V3LinkCells.cpp
+               if (nodep->rangep()) {
+                   string varName = nodep->name() + "__Viftop";  // V3LinkDot looks for this naming
+                   AstIfaceRefDType *idtypep = new AstIfaceRefDType(nodep->fileline(), nodep->name(),
+                                                                    nodep->modp()->name());
+                   idtypep->ifacep(NULL);  // cellp overrides
+
+                   AstNodeArrayDType *newp = new AstUnpackArrayDType(nodep->fileline(),VFlagChildDType(),
+                   AstVar *varp = new AstVar(nodep->fileline(), AstVarType::IFACEREF, varName,
+                                             VFlagChildDType(), newp);
+                   varp->isIfaceParent(true);
+                   nodep->addNextHere(varp);
+                   nodep->hasIfaceVar(true);
+               } else {
+                   string varName = nodep->name() + "__Viftop";  // V3LinkDot looks for this naming
+                   AstIfaceRefDType *idtypep = new AstIfaceRefDType(nodep->fileline(), nodep->name(),
+                                                                    nodep->modp()->name());
+                   idtypep->cellp(nodep);  // Only set when real parent cell known
+                   idtypep->ifacep(NULL);  // cellp overrides
+                   AstVar *varp = new AstVar(nodep->fileline(), AstVarType::IFACEREF, varName,
+                                             VFlagChildDType(), idtypep);
+                   varp->isIfaceParent(true);
+                   nodep->addNextHere(varp);
+                   nodep->hasIfaceVar(true);
+               }

Please move the common code inside the if/else to above/below the if.


+++ b/src/V3Param.cpp
             AstVar* modvarp = pinp->modVarp();
             if (modvarp->isIfaceRef()) {
                 AstIfaceRefDType* portIrefp = modvarp->subDTypep()->castIfaceRefDType();
+               AstIfaceRefDType* pinIrefp = NULL;
+               AstNode *exprp = pinp->exprp();
+               // Wilson: So eh, this is pretty awkward and awfully specific, will likely not work the minute we're not dealing with constants
+               // This can likely be sort of cleaned up with some helpers, but it's really ugly.
+               // Any advice is appreciated
+               if (exprp
+                       && exprp->castVarRef()
+                       && exprp->castVarRef()->varp()
+                       && exprp->castVarRef()->varp()->subDTypep()
+                       && exprp->castVarRef()->varp()->subDTypep()->castIfaceRefDType())
+                       pinIrefp = exprp->castVarRef()->varp()->subDTypep()->castIfaceRefDType();
+               else if (exprp
+                               && exprp->op1p()
+                               && exprp->op1p()->castVarRef()
+                               && exprp->op1p()->castVarRef()->varp()
+                               && exprp->op1p()->castVarRef()->varp()->subDTypep()
+                               && exprp->op1p()->castVarRef()->varp()->subDTypep()->castUnpackArrayDType()
+                               && exprp->op1p()->castVarRef()->varp()->subDTypep()->castUnpackArrayDType()->subDTypep()
+                               && exprp->op1p()->castVarRef()->varp()->subDTypep()->castUnpackArrayDType()->subDTypep()->castIfaceRefDType())

I think this may be ok.  V3Param will already have constants for the sizes,
so that's ok, and there's only a couple of legal formats for connecting to
the interface.