Internals: Improve readability of selects in output (#6980)

src/V3AstNodeExpr.h

@@ -4280,7 +4280,7 @@ public:
     ASTGEN_MEMBERS_AstArraySel;
     void numberOperate(V3Number&, const V3Number&, const V3Number&) override { V3ERROR_NA; }
     string emitVerilog() override { return "%k(%l%f[%r])"; }
-    string emitC() override { return "%li%k[%ri]"; }
+    string emitC() override { V3ERROR_NA_RETURN(""); }  // Special cased
     string emitSMT() const override { return "(select %l %r)"; }
     bool cleanOut() const override { return true; }
     bool cleanLhs() const override { return false; }
@@ -4361,9 +4361,7 @@ public:
     ASTGEN_MEMBERS_AstWordSel;
     void numberOperate(V3Number&, const V3Number&, const V3Number&) override { V3ERROR_NA; }
     string emitVerilog() override { return "%k(%l%f[%r])"; }
-    string emitC() override {
+    string emitC() override { V3ERROR_NA_RETURN(""); }  // Special cased
-        return "%li[%ri]";
-    }  // Not %k, as usually it's a small constant rhsp
     bool cleanOut() const override { return true; }
     bool cleanLhs() const override { return true; }
     bool cleanRhs() const override { return true; }

src/V3EmitCFunc.h

@@ -1651,6 +1651,22 @@ public:
         puts(VSelfPointerText::replaceThis(m_useSelfForThis, "this"));
         puts("}");
     }
+    void visit(AstNodeSel* nodep) override {
+        if (!VN_IS(nodep, ArraySel) && !VN_IS(nodep, WordSel)) {
+            visit(static_cast<AstNodeBiop*>(nodep));
+            return;
+        }
+        // ArraySel or WordSel
+        iterateAndNextConstNull(nodep->fromp());
+        // Special case constant index for readability
+        if (AstConst* const idxp = VN_CAST(nodep->bitp(), Const)) {
+            puts("[" + std::to_string(idxp->toUInt()) + "U]");
+            return;
+        }
+        putbs("[");
+        iterateAndNextConstNull(nodep->bitp());
+        puts("]");
+    }
 
     //
     void visit(AstConsAssoc* nodep) override {