Error to compile when applying Single Script Linker - gwt

Question

Because I am creating a chrome extension with GWT project, I want to use Single Script Linker to avoid inline scripting restriction (sigh...).
And I found this resource on line: http://tech-drum.blogspot.ch/2012/08/gwt-chrome-extension-using-version-2.html
This single script linker looks like a charm, but when I really added it into my gwt.xml file and compile, it got errors... (sigh again)
The following is the error msg:
[INFO] --- gwt-maven-plugin:2.5.1:compile (default) # fake-app ---
[INFO] auto discovered modules [com.fake...]
[INFO] Compiling module com.fake.name.app
[INFO] Compiling 6 permutations
[INFO] Compiling permutation 0...
[INFO] Process output
[INFO] Compiling
[INFO] Compiling permutation 3...
[INFO] Process output
[INFO] Compiling
[INFO] Compiling permutation 1...
[INFO] Process output
[INFO] Compiling
[INFO] Compiling permutation 2...
[INFO] Compiling permutation 4...
[INFO] Compiling permutation 5...
[INFO] Compile of permutations succeeded
[INFO] Linking into /path/to/fake/app
[INFO] Invoking Linker Single Script
[INFO] [ERROR] The module must have exactly one distinct permutation when using the Single Script Linker; found 6
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
What's the problem with this? It looks that permutation number (assumed as js file?) to be larger than expected, but shouldn't the linker put size restriction when creating permutations? In short, how to fix this? Thanks a lot!

Answer 1

Selecting just the user agent for Chrome should fix your problem.
You don't need more user-agent permutations since your extension only works with one browser.
The linker you are using is the correct one for producing just a javascript file with the code of your extension.
<set-property name="user.agent" value="safari" />

Answer 2

The linker runs after the code is compiled, it can't make judgements about the output until that point. This particular linker expects to produce exactly one JS file (plus images, etc perhaps, but not more code) hence 'single script'. Generating more than one permutation prevents it from doing its job.
Consider selecting a different linker, or combining all of the properties you are using (likely just user.agent) into one permutation with this in your module file (from http://code.google.com/p/google-web-toolkit/wiki/SoftPermutations):
<collapse-all-properties />