Add IMPORTSTAR warning on import::* inside scope.

Changes

@@ -12,6 +12,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Add PROCASSWIRE error on behavioral assignments to wires, msg2737. [Neil Turton]
 
+****  Add IMPORTSTAR warning on import::* inside $unit scope.
+
 ****  Fix --trace-lxt2 compile error on MinGW, msg2711. [HyungKi Jeong]
 
 ****  Fix hang on bad pattern keys, bug1364. [Matt Myers]

bin/verilator

@@ -226,7 +226,7 @@ Verilator - Convert Verilog code to C++/SystemC
     verilator --version
     verilator --cc [options] [source_files.v]... [opt_c_files.cpp/c/cc/a/o/so]
     verilator --sc [options] [source_files.v]... [opt_c_files.cpp/c/cc/a/o/so]
-    verilator --lint-only    [source_files.v]...
+    verilator --lint-only -Wall [source_files.v]...
 
 =head1 DESCRIPTION
 
@@ -1414,8 +1414,8 @@ received from third parties.
 
 Disable all code style related warning messages (note by default they are
 already disabled).  This is equivalent to "-Wno-DECLFILENAME -Wno-DEFPARAM
--Wno-INCABSPATH -Wno-PINCONNECTEMPTY -Wno-PINNOCONNECT -Wno-SYNCASYNCNET
--Wno-UNDRIVEN -Wno-UNUSED -Wno-VARHIDDEN".
+-Wno-IMPORTSTAR -Wno-INCABSPATH -Wno-PINCONNECTEMPTY -Wno-PINNOCONNECT
+-Wno-SYNCASYNCNET -Wno-UNDRIVEN -Wno-UNUSED -Wno-VARHIDDEN".
 
 =item -Wno-fatal
 
@@ -3579,6 +3579,16 @@ Emacs, available from L<http://www.veripool.org/>
 Ignoring this warning will only suppress the lint check, it will simulate
 correctly.
 
+=item IMPORTSTAR
+
+Warns that an "import I<package>::*" statement is in $unit scope. This
+causes the imported symbols to polute the global namespace, defeating much
+of the purpose of having a package. Generally "import ::*" should only be
+used inside a lower scope such as a package or module.
+
+Disabled by default as this is a code style warning; it will simulate
+correctly.
+
 =item IMPURE
 
 Warns that a task or function that has been marked with /*verilator

src/V3Error.h

@@ -77,8 +77,9 @@ public:
 	GENCLK,		// Generated Clock
 	IFDEPTH,	// If statements too deep
 	IMPERFECTSCH,	// Imperfect schedule (disabled by default)
-	IMPLICIT,	// Implicit wire
-	IMPURE,		// Impure function not being inlined
+        IMPLICIT,       // Implicit wire
+        IMPORTSTAR,     // Import::* in $unit
+        IMPURE,         // Impure function not being inlined
 	INCABSPATH,	// Include has absolute path
         INFINITELOOP,   // Infinite loop
 	INITIALDLY,	// Initial delayed statement
@@ -136,7 +137,7 @@ public:
             "CMPCONST", "COLONPLUS", "COMBDLY",
             "DEFPARAM", "DECLFILENAME",
             "ENDLABEL", "GENCLK",
-            "IFDEPTH", "IMPERFECTSCH", "IMPLICIT", "IMPURE",
+            "IFDEPTH", "IMPERFECTSCH", "IMPLICIT", "IMPORTSTAR", "IMPURE",
             "INCABSPATH", "INFINITELOOP", "INITIALDLY",
             "LITENDIAN", "MODDUP",
             "MULTIDRIVEN",
@@ -185,9 +186,10 @@ public:
 				       || m_e==BLKSEQ
 				       || m_e==DEFPARAM
 				       || m_e==DECLFILENAME
-				       || m_e==INCABSPATH
-				       || m_e==PINCONNECTEMPTY
-				       || m_e==PINNOCONNECT
+                                       || m_e==IMPORTSTAR
+                                       || m_e==INCABSPATH
+                                       || m_e==PINCONNECTEMPTY
+                                       || m_e==PINNOCONNECT
 				       || m_e==SYNCASYNCNET
 				       || m_e==UNDRIVEN
 				       || m_e==UNUSED

src/V3LinkDot.cpp

@@ -1020,7 +1020,11 @@ class LinkDotFindVisitor : public AstNVisitor {
     virtual void visit(AstPackageImport* nodep) {
 	UINFO(4,"  Link: "<<nodep<<endl);
 	VSymEnt* srcp = m_statep->getNodeSym(nodep->packagep());
-	if (nodep->name()!="*") {
+        if (nodep->name()=="*") {
+            if (m_curSymp == m_statep->dunitEntp()) {
+                nodep->v3warn(IMPORTSTAR,"Import::* in $unit scope may pollute global namespace");
+            }
+        } else {
 	    VSymEnt* impp = srcp->findIdFlat(nodep->name());
 	    if (!impp) {
 		nodep->v3error("Import object not found: "<<nodep->packagep()->prettyName()<<"::"<<nodep->prettyName());

test_regress/t/t_lint_importstar_bad.out

@@ -0,0 +1,3 @@
+%Warning-IMPORTSTAR: t/t_lint_importstar_bad.v:10: Import::* in $unit scope may pollute global namespace
+%Warning-IMPORTSTAR: Use "/* verilator lint_off IMPORTSTAR */" and lint_on around source to disable this message.
+%Error: Exiting due to

test_regress/t/t_lint_importstar_bad.pl

@@ -0,0 +1,23 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 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.
+
+scenarios(vlt_all => 1);
+
+compile(
+    v_flags2 => ["--lint-only -Wall -Wno-DECLFILENAME"],
+    fails => 1,
+    verilator_make_gcc => 0,
+    make_top_shell => 0,
+    make_main => 0,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
+

test_regress/t/t_lint_importstar_bad.v

@@ -0,0 +1,13 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2018 by Wilson Snyder.
+
+package defs;
+   int sig;
+endpackage
+
+import defs::*;
+
+module t;
+endmodule