Change MODDUP errors to warnings, msg2588.

Changes

@@ -12,6 +12,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix std:: build error, bug1322.
 
+****  Change MODDUP errors to warnings, msg2588. [Marshal Qiao]
+
 
 * Verilator 3.924 2018-06-12
 

bin/verilator

@@ -3361,10 +3361,14 @@ correctly.
 
 =item MODDUP
 
-Error that a module has multiple definitions.  Generally this indicates a
+Warns that a module has multiple definitions.  Generally this indicates a
 coding error, or a mistake in a library file and it's good practice to have
-one module per file to avoid these issues.  For some gate level netlists
-duplicates are unavoidable, and this error may be disabled.
+one module per file (and only put each file once on the command line) to
+avoid these issues.  For some gate level netlists duplicates are sometimes
+unavoidable, and MODDUP should be disabled.
+
+Ignoring this warning will cause the more recent module definition to be
+discarded.
 
 =item MULTIDRIVEN
 

src/V3Error.h

@@ -154,7 +154,7 @@ public:
     // Later -Werror- options may make more of these.
     bool pretendError() const { return ( m_e==ASSIGNIN || m_e==BLKANDNBLK
 					 || m_e==BLKLOOPINIT
-					 || m_e==IMPURE || m_e==MODDUP); }
+					 || m_e==IMPURE); }
     // Warnings to mention manual
     bool mentionManual() const { return ( m_e==EC_FATALSRC || m_e==SYMRSVDWORD
 					  || pretendError() ); }

test_regress/t/t_mod_dup_bad.pl

@@ -12,8 +12,8 @@ scenarios(vlt_all => 1);
 compile(
     fails => 1,
     expect =>
-'%Error-MODDUP: t/t_mod_dup_bad.v:\d+: Duplicate declaration of module: a
-%Error-MODDUP: t/t_mod_dup_bad.v:\d+: ... Location of original declaration
+'%Warning-MODDUP: t/t_mod_dup_bad.v:\d+: Duplicate declaration of module: a
+%Warning-MODDUP: t/t_mod_dup_bad.v:\d+: ... Location of original declaration
 .*
 %Error: Exiting due to.*',
     );