Fix internal error when task without CFunc is left in the tree (#8437)

Signed-off-by: Artur Bieniek <[email protected]>

src/V3Task.cpp

@@ -1629,6 +1629,18 @@ class TaskVisitor final : public VNVisitor {
         // Includes handling AstMethodCall, AstNew
         UASSERT_OBJ(nodep->taskp(), nodep, "Unlinked?");
         iterateIntoFTask(nodep->taskp());  // First, do hierarchical funcs
+        if (m_statep->ftaskNoInline(nodep->taskp()) && !m_statep->ftaskCFuncp(nodep->taskp())) {
+            // An earlier error (e.g. a DPI import declared twice with conflicting
+            // signatures) prevented creating the function, so remove the call
+            UASSERT_OBJ(V3Error::errorCount(), nodep, "No non-inline task, but no error issued");
+            if (VN_IS(nodep->backp(), StmtExpr)) {
+                VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
+            } else {
+                nodep->replaceWith(new AstConst{nodep->fileline(), AstConst::BitFalseErroring{}});
+                VL_DO_DANGLING(pushDeletep(nodep), nodep);
+            }
+            return;
+        }
         UINFO(4, " FTask REF   " << nodep);
         UINFOTREE(9, nodep, "", "inlfunc");
         UASSERT_OBJ(m_scopep, nodep, "func ref not under scope");

test_regress/t/t_dpi_argtype_bad.v

@@ -14,7 +14,9 @@ module t;
   } foo_t;
 
   import "DPI-C" task dpix_twice(foo_t arg);
+  foo_t f;
   initial begin
+    dpix_twice(f);
     $stop;
   end
 endmodule

test_regress/t/t_dpi_dup_bad.out

@@ -6,4 +6,11 @@
    12 |   import "DPI-C" dpii_fa_bit = function int oth_f_int1(input int i);
       |                                             ^~~~~~~~~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: t/t_dpi_dup_bad.v:19:47: Duplicate declaration of DPI function with different signature: 'dpii_fa_void'
+   19 |   import "DPI-C" dpii_fa_void = function void oth_f_void2(
+      |                                               ^~~~~~~~~~~
+                               : ... New signature:      void dpii_fa_void (int, int)
+        t/t_dpi_dup_bad.v:18:47: ... Original signature: void dpii_fa_void (int)
+   18 |   import "DPI-C" dpii_fa_void = function void oth_f_void1(input int i);
+      |                                               ^~~~~~~~~~~
 %Error: Exiting due to

test_regress/t/t_dpi_dup_bad.v

@@ -14,7 +14,20 @@ module t;
     input int i,
     input int bad);
 
+  // Same, but void so the call sits in statement position
+  import "DPI-C" dpii_fa_void = function void oth_f_void1(input int i);
+  import "DPI-C" dpii_fa_void = function void oth_f_void2(
+    input int i,
+    input int bad);
+
+  int o1;
+  int o2;
+
   initial begin
+    o1 = oth_f_int1(1);
+    o2 = oth_f_int2(1, 2);
+    oth_f_void1(1);
+    oth_f_void2(1, 2);
     $stop;
   end