--output silently does nothing for HTML

[m-renaud]

Overview

Edit: Changed issue title, somehow missed that HTML support isn't available.

So I was going to go through http://www.serpentine.com/criterion/tutorial.html to see if all the instructions there also work without modification for Gauge and discovered that the --output=file.html doesn't appear to work (or I'm holding it wrong). The benchmark completes successfully but doesn't write an output file.

Steps to Reproduce

1. Visit http://www.serpentine.com/criterion/tutorial.html
2. Create the file Fibber.hs with the content of the code block under the Getting Started section but replace import Criterion.Main with import Gauge
3. ghc -O --make Fibber
4. ./Fibber --output=fibber.html

Checking the help options (./Fibber --help) it appears that --output is a valid option.

Other info

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.4.4

$ ./Fibber --help
Microbenchmark suite - built with gauge 0.2.4
<snip>
  -o FILE   --output=FILE             File to write report to
<snip>

[m-renaud]

So, I'm silly, I just re-read the readme and noticed that it explicitly says HTML support is missing, so I guess this issue is more that it doesn't emit a warning or message when you request unsupported output.