From 590ad964b1d5f3e6a0d3c1b3066a48453d219faf Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sun, 13 Aug 2017 18:08:44 -0400
Subject: [PATCH] Add assertion on bad formed lvalues, used to debug bug1187.

---
 src/V3Ast.h      | 1 +
 src/V3AstNodes.h | 7 +++++++
 src/V3Broken.cpp | 9 +++++++++
 3 files changed, 17 insertions(+)

diff --git a/src/V3Ast.h b/src/V3Ast.h
index 2f8a75bab..12e6e0506 100644
--- a/src/V3Ast.h
+++ b/src/V3Ast.h
@@ -1512,6 +1512,7 @@ public:
     virtual V3Hash sameHash() const { return V3Hash(); }
     virtual bool same(AstNode*) const { return true; }
     virtual string verilogKwd() const { return "="; }
+    virtual bool brokeLhsMustBeLvalue() const = 0;
 };
 
 class AstNodeFor : public AstNodeStmt {
diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index 5587c71d5..c93324dd9 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -2039,6 +2039,7 @@ public:
     }
     ASTNODE_NODE_FUNCS(Assign)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssign(this->fileline(), lhsp, rhsp); }
+    virtual bool brokeLhsMustBeLvalue() const { return true; }
 };
 
 class AstAssignAlias : public AstNodeAssign {
@@ -2049,6 +2050,7 @@ public:
 	: AstNodeAssign(fileline, lhsp, rhsp) {}
     ASTNODE_NODE_FUNCS(AssignAlias)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { V3ERROR_NA; return NULL; }
+    virtual bool brokeLhsMustBeLvalue() const { return false; }
 };
 
 class AstAssignDly : public AstNodeAssign {
@@ -2059,6 +2061,7 @@ public:
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssignDly(this->fileline(), lhsp, rhsp); }
     virtual bool isGateOptimizable() const { return false; }
     virtual string verilogKwd() const { return "<="; }
+    virtual bool brokeLhsMustBeLvalue() const { return true; }
 };
 
 class AstAssignW : public AstNodeAssign {
@@ -2068,6 +2071,7 @@ public:
 	: AstNodeAssign(fileline, lhsp, rhsp) { }
     ASTNODE_NODE_FUNCS(AssignW)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssignW(this->fileline(), lhsp, rhsp); }
+    virtual bool brokeLhsMustBeLvalue() const { return true; }
     AstAlways* convertToAlways() {
 	AstNode* lhs1p = lhsp()->unlinkFrBack();
 	AstNode* rhs1p = rhsp()->unlinkFrBack();
@@ -2087,6 +2091,7 @@ public:
     }
     ASTNODE_NODE_FUNCS(AssignVarScope)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssignVarScope(this->fileline(), lhsp, rhsp); }
+    virtual bool brokeLhsMustBeLvalue() const { return false; }
 };
 
 class AstPull : public AstNode {
@@ -2113,6 +2118,7 @@ public:
 	: AstNodeAssign(fileline, lhsp, rhsp) {}
     ASTNODE_NODE_FUNCS(AssignPre)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssignPre(this->fileline(), lhsp, rhsp); }
+    virtual bool brokeLhsMustBeLvalue() const { return true; }
 };
 
 class AstAssignPost : public AstNodeAssign {
@@ -2122,6 +2128,7 @@ public:
 	: AstNodeAssign(fileline, lhsp, rhsp) {}
     ASTNODE_NODE_FUNCS(AssignPost)
     virtual AstNode* cloneType(AstNode* lhsp, AstNode* rhsp) { return new AstAssignPost(this->fileline(), lhsp, rhsp); }
+    virtual bool brokeLhsMustBeLvalue() const { return true; }
 };
 
 class AstComment : public AstNodeStmt {
diff --git a/src/V3Broken.cpp b/src/V3Broken.cpp
index c490b6f08..090b8d5fa 100644
--- a/src/V3Broken.cpp
+++ b/src/V3Broken.cpp
@@ -236,6 +236,15 @@ private:
 	nodep->iterateChildrenConst(*this);
 	BrokenTable::setUnder(nodep,false);
     }
+    virtual void visit(AstNodeAssign* nodep) {
+	processAndIterate(nodep);
+	if (v3Global.assertDTypesResolved()
+	    && nodep->brokeLhsMustBeLvalue()
+	    && nodep->lhsp()->castNodeVarRef()
+	    && !nodep->lhsp()->castNodeVarRef()->lvalue()) {
+	    nodep->v3fatalSrc("Assignment LHS is not an lvalue");
+	}
+    }
     virtual void visit(AstNode* nodep) {
 	processAndIterate(nodep);
     }