Warning whitelist doesn't work in Google closure compiler

Question

The manual says I can use:

 --warnings_whitelist_file VAL          : A file containing warnings to
                                          suppress. Each line should be of the
                                          form
                                          <file-name>:<line-number>?  <warning-d
                                          escription>

This is what my whitelist looks like:

ef-utils.js:1  Redeclared variable: ef
ef-utils.js:1  Variable ef first declared in externs-ko.js
ef-validation.js:1  Redeclared variable: ef
ef-validation.js:1  Variable ef first declared in externs-ko.js

And I am still getting warnings while compiling:

ef-utils.js:1: WARNING - Redeclared variable: ef
?var ef = (function (ns, ko) {
     ^

ef-utils.js:1: WARNING - Variable ef first declared in externs-ko.js
?var ef = (function (ns, ko) {
     ^

ef-validation.js:1: WARNING - Redeclared variable: ef
?var ef = (function (ns, ko) {
     ^

ef-validation.js:1: WARNING - Variable ef first declared in externs-ko.js
?var ef = (function (ns, ko) {
     ^

Answer 1

I just toyed around with the current WhitelistWarningsGuard. I found out that

• Line numbers are completely ignored: they are stripped both from the input file and the encountered warnings.
• File names are formatted as they are for output, i.e. as they occur on the command line.
• There is a colon after the file name, followed by two spaces, followed by the message text without indicator of the severity (WARNING, ERROR).
• The main effect of the whitelist appears to be turning errors into warnings. So when applied to warnings, there will be no effect at all.
• The WhitelistBuilder mentioned by Tibos is there in the code, but I see no way to use it from the command line.

As it is, that feature appears to be mostly useless for my use cases…