Fix error when multiple duplicate DPI exports (#4301).

Changes

@@ -14,6 +14,7 @@ Verilator 5.013 devel
 **Minor:**
 
 * Deprecation planned for 32-bit pointer -m32 mode (#4268).
+* Fix error when multiple duplicate DPI exports (#4301).
 
 
 Verilator 5.012 2023-06-13

src/V3Task.cpp

@@ -657,8 +657,15 @@ private:
                         args += ", ";
                         dpiproto += ", ";
                     }
+                    // Include both the Verilator and C type names, as if either
+                    // differ we may get C compilation problems later
+                    const std::string dpiType = portp->dpiArgType(false, false);
+                    dpiproto += dpiType;
+                    const std::string vType = portp->dtypep()->prettyDTypeName();
+                    if (!portp->isDpiOpenArray() && dpiType != vType) {
+                        dpiproto += " /* " + vType + " */ ";
+                    }
                     args += portp->name();  // Leftover so ,'s look nice
-                    if (nodep->dpiImport()) dpiproto += portp->dpiArgType(false, false);
                 }
             }
         }
@@ -929,15 +936,15 @@ private:
             m_dpiNames.emplace(nodep->cname(), std::make_tuple(nodep, signature, funcp));
             return funcp;
         } else {
-            // Seen this cname before. Check if it's the same prototype.
+            // Seen this cname import before. Check if it's the same prototype.
             const AstNodeFTask* firstNodep;
             string firstSignature;
             AstCFunc* firstFuncp;
             std::tie(firstNodep, firstSignature, firstFuncp) = it->second;
             if (signature != firstSignature) {
                 // Different signature, so error.
-                nodep->v3error("Duplicate declaration of DPI function with different signature: "
+                nodep->v3error("Duplicate declaration of DPI function with different signature: '"
-                               << nodep->prettyNameQ() << '\n'
+                               << nodep->cname() << "'\n"
                                << nodep->warnContextPrimary() << '\n'
                                << nodep->warnMore()  //
                                << "... New signature:      " << signature << '\n'  //

test_regress/t/t_dpi_2exparg_bad.out

@@ -0,0 +1,18 @@
+%Warning-WIDTHEXPAND: t/t_dpi_2exparg_bad.v:19:56: Operator NOT expects 64 bits on the LHS, but LHS's VARREF 'i' generates 32 bits.
+                                                 : ... In instance t.b
+   19 |    task dpix_twice(input int i, output [63:0] o);  o = ~i; endtask
+      |                                                        ^
+                      ... For warning description see https://verilator.org/warn/WIDTHEXPAND?v=latest
+                      ... Use "/* verilator lint_off WIDTHEXPAND */" and lint_on around source to disable this message.
+%Warning-WIDTHTRUNC: t/t_dpi_2exparg_bad.v:12:53: Operator ASSIGN expects 3 bits on the Assign RHS, but Assign RHS's NOT generates 32 bits.
+                                                : ... In instance t.a
+   12 |    task dpix_twice(input int i, output [2:0] o);  o = ~i; endtask
+      |                                                     ^
+%Error: t/t_dpi_2exparg_bad.v:19:9: Duplicate declaration of DPI function with different signature: 'dpix_twice'
+   19 |    task dpix_twice(input int i, output [63:0] o);  o = ~i; endtask
+      |         ^~~~~~~~~~
+                                  : ... New signature:      void dpix_twice (int, svLogicVecVal* /* logic[63:0] */ )
+        t/t_dpi_2exparg_bad.v:12:9: ... Original signature: void dpix_twice (int, svLogicVecVal* /* logic[2:0] */ )
+   12 |    task dpix_twice(input int i, output [2:0] o);  o = ~i; endtask
+      |         ^~~~~~~~~~
+%Error: Exiting due to

test_regress/t/t_dpi_2exparg_bad.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(linter => 1);
+
+lint(
+    fails => $Self->{vlt_all},
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_dpi_2exparg_bad.v

@@ -0,0 +1,30 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// Copyright 2023 by Wilson Snyder. This program is free software; you can
+// redistribute it and/or modify it under the terms of either the GNU
+// Lesser General Public License Version 3 or the Perl Artistic License
+// Version 2.0.
+// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+module a;
+   import "DPI-C" task dpii_twice;  // Legal
+   export "DPI-C" task dpix_twice;  // Bad
+   task dpix_twice(input int i, output [2:0] o);  o = ~i; endtask
+   initial dpii_twice();
+endmodule
+
+module b;
+   import "DPI-C" task dpii_twice;  // Legal
+   export "DPI-C" task dpix_twice;  // Bad
+   task dpix_twice(input int i, output [63:0] o);  o = ~i; endtask
+   initial dpii_twice();
+endmodule
+
+module t;
+   a a();
+   b b();
+
+   initial begin
+      $stop;
+   end
+endmodule

test_regress/t/t_dpi_dup_bad.out

@@ -1,4 +1,4 @@
-%Error: t/t_dpi_dup_bad.v:13:51: Duplicate declaration of DPI function with different signature: 't.oth_f_int2'
+%Error: t/t_dpi_dup_bad.v:13:51: Duplicate declaration of DPI function with different signature: 'dpii_fa_bit'
    13 |    import "DPI-C" pure dpii_fa_bit = function int oth_f_int2(input int i, input int bad);
       |                                                   ^~~~~~~~~~
                                : ... New signature:      pure int dpii_fa_bit (int, int)