Fix associative array next/prev/first/last mis-propagating constants (#5435).

Changes

@@ -33,6 +33,7 @@ Verilator 5.029 devel
 * Fix sformatf internal error on initial automatics (#5423). [Todd Strader]
 * Fix clearing trigger of events with no sensitivity trees (#5426). [Arkadiusz Kozdra, Antmicro Ltd.]
 * Fix driving clocking block in reactive region (#5430). [Krzysztof Bieganski, Antmicro Ltd.]
+* Fix associative array next/prev/first/last mis-propagating constants (#5435). [Ethan Sifferman]
 
 
 Verilator 5.028 2024-08-21

src/V3Ast.h

@@ -215,7 +215,7 @@ public:
         return names[m_e];
     }
     const char* arrow() const {
-        static const char* const names[] = {"[RV] <-", "[LV] =>", "[LV] <=>", "--"};
+        static const char* const names[] = {"[RV] <-", "[LV] =>", "[LRV] <=>", "--"};
         return names[m_e];
     }
     VAccess()

src/V3Width.cpp

@@ -3432,6 +3432,7 @@ class WidthVisitor final : public VNVisitor {
                    || nodep->name() == "prev") {
             methodOkArguments(nodep, 1, 1);
             AstNodeExpr* const index_exprp = methodCallAssocIndexExpr(nodep, adtypep);
+            methodCallLValueRecurse(nodep, index_exprp, VAccess::READWRITE);
             newp = new AstCMethodHard{nodep->fileline(), nodep->fromp()->unlinkFrBack(),
                                       nodep->name(),  // first/last/next/prev
                                       index_exprp->unlinkFrBack()};

test_regress/t/t_assoc.v

@@ -121,6 +121,29 @@ module t (/*AUTOARG*/
          `checkh(sum, 1 + 2);
       end
 
+      begin   // Issue #5435
+         int a;
+         int ok;
+         int dict [int];
+
+         dict[3] = 'h13;
+         dict[4] = 'h14;
+         dict[5] = 'h15;
+
+         a = 4;
+         ok = dict.first(a);
+         if (a != 3) $stop;
+         if (ok != 1) $stop;
+         a = 4;
+         ok = dict.next(a);
+         if (a != 5) $stop;
+         if (ok != 1) $stop;
+         a = 4;
+         ok = dict.last(a);
+         if (a != 5) $stop;
+         if (ok != 1) $stop;
+      end
+
       $write("*-* All Finished *-*\n");
       $finish;
    end

test_regress/t/t_assoc_method_bad.out

@@ -18,6 +18,11 @@
                                     : ... note: In instance 't'
    18 |       v = a.first();   
       |             ^~~~~
+%Error-UNSUPPORTED: t/t_assoc_method_bad.v:18:13: Unsupported: Non-variable on LHS of built-in method 'first'
+                                                : ... note: In instance 't'
+   18 |       v = a.first();   
+      |             ^~~~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
 %Error: t/t_assoc_method_bad.v:19:13: The 2 arguments passed to .next method does not match its requiring 1 arguments
                                     : ... note: In instance 't'
    19 |       v = a.next(k, "bad2");   
@@ -26,6 +31,10 @@
                                     : ... note: In instance 't'
    20 |       v = a.last();   
       |             ^~~~
+%Error-UNSUPPORTED: t/t_assoc_method_bad.v:20:13: Unsupported: Non-variable on LHS of built-in method 'last'
+                                                : ... note: In instance 't'
+   20 |       v = a.last();   
+      |             ^~~~
 %Error: t/t_assoc_method_bad.v:21:13: The 2 arguments passed to .prev method does not match its requiring 1 arguments
                                     : ... note: In instance 't'
    21 |       v = a.prev(k, "bad2");