Summary

The javac command-line help for the --module option should be changed to match the implementation.

Problem

The command line help for --module / -m indicates that it only takes a single module-name as an argument. In fact, it accepts a comma-separated list of names.

In addition, this option is inconsistent with regard to other options that accept modules names. The command-line help for --module uses <module-name>, but other options just use <module> to match the runtime behavior. The runtime equivalent for --module also uses <module>.

Solution

Update the command-line help to indicate that it accepts a comnma-separate list of module names, represented by <module>

Specification

$ hg diff
diff -r 28ec06beb091 src/jdk.compiler/share/classes/com/sun/tools/javac/resources/javac.properties
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/javac.properties     Tue Jan 08 13:04:04 2019 -0800
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/javac.properties     Tue Jan 08 16:56:05 2019 -0800
@@ -44,7 +44,7 @@
 javac.opt.sourcepath=\
     Specify where to find input source files
 javac.opt.m=\
-    Compile only the specified module, check timestamps
+    Compile only the specified module(s), check timestamps
 javac.opt.modulesourcepath=\
     Specify where to find input source files for multiple modules
 javac.opt.bootclasspath=\
@@ -108,7 +108,7 @@
 javac.opt.arg.mspath=\
     <module-source-path>
 javac.opt.arg.m=\
-    <module-name>
+    <module>(,<module>)*
 javac.opt.arg.jdk=\
     <jdk>|none
 javac.opt.arg.dirs=\

With those edits, the command-line help for the --module option will appear as follows:

  --module <module>(,<module>)*, -m <module>(,<module>)*
        Compile only the specified module(s), check timestamps