Fix // in filenames, bug1610.

Changes

@@ -22,6 +22,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix VPI timed callbacks to be one-shot, pull5. [Matthew Ballance]
 
+****  Fix // in filenames, bug1610. [Peter Nelson]
+
 
 * Verilator 4.022 2019-11-10
 

src/V3Options.cpp

@@ -1247,13 +1247,15 @@ void V3Options::parseOptsFile(FileLine* fl, const string& filename, bool rel) {
         // Strip simple comments
         string oline;
         // cppcheck-suppress StlMissingComparison
-        for (string::const_iterator pos = line.begin(); pos != line.end(); ++pos) {
+        char lastch = ' ';
+        for (string::const_iterator pos = line.begin(); pos != line.end(); lastch = *pos++) {
             if (inCmt) {
                 if (*pos=='*' && *(pos+1)=='/') {
                     inCmt = false;
                     ++pos;
                 }
-            } else if (*pos=='/' && *(pos+1)=='/') {
+            } else if (*pos=='/' && *(pos+1)=='/'
+                       && (pos == line.begin() || isspace(lastch))) {    // But allow /file//path
                 break;  // Ignore to EOL
             } else if (*pos=='/' && *(pos+1)=='*') {
                 inCmt = true;

test_regress/t/t_flag_f.vc

@@ -1,6 +1,7 @@
 // Test that environment substitutions work
 -f $VERILATOR_ROOT/test_regress/t/t_flag_f__2.vc
 // Env var with .v file, and parens
-${VERILATOR_ROOT}/test_regress/t/t_flag_f__3.v
+// Double slash below is intentional, as allowed in other tools
+${VERILATOR_ROOT}/test_regress/t//t_flag_f__3.v
 // Test -f
 -F $VERILATOR_ROOT/test_regress/t/tsub/t_flag_f_tsub.vc