Enabling Migration Warnings - scala

Question

I am porting a 2.7.7 scala code base over to 2.8 and was wondering if there was a compiler option to display migration notices? I was bitten by a change in behavior for mutable sequences that had the following migration notice[1], however it doesn't display anything when I build the project ( I have deprecation and unchecked warnings enabled already)
1: #migration(2, 8,
"As of 2.8, this operation creates a new map. To add an element as a\n"+
"side effect to an existing map and return that map itself, use +=."
)

Answer 1

The option is: -Xmigration
Entering scalac -help will show the standard options of the Scala compiler.
Entering scalac -X will show the advanced options.
Entering scalac -Y will show the private options.

Answer 2

It's a extended option, -Xmigration.
~: scala -X
Usage: scala <options> <source files>
Possible advanced options include:
-Xassem-extdirs <dirs> List of directories containing assemblies, defaults to `lib'
-Xassem-name <file> Name of the output assembly (only relevant with -target:msil)
-Xassem-path <path> List of assemblies referenced by the program (only relevant with -target:msil)
-Xcheck-null Emit warning on selection of nullable reference
-Xcheckinit Add runtime checks on field accessors. Uninitialized accesses result in an exception being thrown.
-Xdisable-assertions Generate no assertions and assumptions
-Xelide-below Generate calls to #elidable-marked methods only if method priority is greater than argument.
-Xexperimental Enable experimental extensions
-Xfatal-warnings Fail the compilation if there are any warnings.
-Xfuture Turn on future language features
-Xgenerate-phase-graph <file> Generate the phase graphs (outputs .dot files) to fileX.dot
-Xlog-implicits Show more info on why some implicits are not applicable
-Xmigration Warn about constructs whose behavior may have changed between 2.7 and 2.8
-Xno-forwarders Do not generate static forwarders in mirror classes
-Xno-uescape Disables handling of \u unicode escapes
-Xnojline Do not use JLine for editing
-Xplugin-disable:<plugin> Disable a plugin
-Xplugin-list Print a synopsis of loaded plugins
-Xplugin-require:<plugin> Abort unless a plugin is available
-Xplugin:<file> Load a plugin from a file
-Xpluginsdir <path> Path to search compiler plugins
-Xprint-icode Log internal icode to *.icode files
-Xprint-pos Print tree positions (as offsets)
-Xprint-types Print tree types (debugging option)
-Xprint:<phase> Print out program after <phase> or "all"
-Xprompt Display a prompt after each error (debugging option)
-Xresident Compiler stays resident, files to compile are read from standard input
-Xscript <object> Compile as a script, wrapping the code into object.main()
-Xshow-class <class> Show class info
-Xshow-object <object> Show object info
-Xshow-phases Print a synopsis of compiler phases
-Xsource-reader <classname> Specify a custom method for reading source files
-Xsourcedir <directory> When -target:msil, the source folder structure is mirrored in output directory.
-Xwarninit Warn about possible changes in initialization semantics
-Y Print a synopsis of private options

Answer 3

% scala -X
Usage: scala <options> <source files>
Possible advanced options include:
...
-Xmigration Warn about constructs whose behavior may have changed between 2.7 and 2.8
...