bash completion: Fix case when no current word index specified

application/argumentparser.cpp

@@ -683,11 +683,11 @@ void ArgumentParser::readArgs(int argc, const char *const *argv)
                 // the first argument after "--bash-completion-for" is the index of the current word
                 try {
                     currentWordIndex = (--argc ? stringToNumber<unsigned int, string>(*(++argv)) : 0);
+                    if (argc) {
+                        ++argv, --argc;
+                    }
                 } catch (const ConversionException &) {
-                    currentWordIndex = static_cast<unsigned int>(argc);
-                }
-                if (argc) {
-                    ++argv, --argc;
+                    currentWordIndex = static_cast<unsigned int>(argc - 1);
                 }
             }
 

tests/argumentparsertests.cpp

@@ -599,6 +599,28 @@ void ArgumentParserTests::testBashCompletion()
         cout.rdbuf(regularCoutBuffer);
         CPPUNIT_ASSERT_EQUAL(static_cast<string::size_type>(0), buffer.str().find("COMPREPLY=('--fields' "));
 
+        // override exit function to prevent readArgs() from terminating the test run
+        exitFunction = [](int) {};
+
+        // call completion via readArgs() with current word index
+        const char *const argv10[] = { "/some/path/tageditor", "--bash-completion-for", "0" };
+        buffer.str(string());
+        cout.rdbuf(buffer.rdbuf());
+        parser.resetArgs();
+        parser.readArgs(3, argv10);
+        cout.rdbuf(regularCoutBuffer);
+        CPPUNIT_ASSERT(!strcmp("/some/path/tageditor", parser.executable()));
+        CPPUNIT_ASSERT_EQUAL("COMPREPLY=('display-file-info' 'get' 'set' '--help' )\n"s, buffer.str());
+
+        // call completion via readArgs() without current word index
+        const char *const argv11[] = { "/some/path/tageditor", "--bash-completion-for", "ge" };
+        buffer.str(string());
+        cout.rdbuf(buffer.rdbuf());
+        parser.resetArgs();
+        parser.readArgs(3, argv11);
+        cout.rdbuf(regularCoutBuffer);
+        CPPUNIT_ASSERT_EQUAL("COMPREPLY=('get' )\n"s, buffer.str());
+
     } catch (...) {
         cout.rdbuf(regularCoutBuffer);
         throw;