Range comparison takes longer than needed for sufficiently large ranges when expectation not met

Due to a failed expectation running a diff on the objects involved, an expectation which involves sufficiently large ranges will iterate over every element of each range for message output upon failure. This is due to line 27 of lib/rspec/expectations/fail_with.rb

Example:

expect(1..10).to eq (1..2)

will result in:

RSpec::Expectations::ExpectationNotMetError:
expected: 1..2
     got: 1..10

(compared using ==)

Diff:
@@ -1,2 +1,2 @@
-[1, 2]
+[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

As you can see, if the range is of, say a date range spanning years, or a boundary is Float::INFINITY, the diff can take a lot of unnecessary time and screen space.

Suggested fix: wrap a conditional to check if expected or actual are ranges, and specialize output to deal with the boundaries of those ranges, rather than each element.

Start at line 27 of lib/rspec/expectations/fail_with.rb and reproduce the range comparison example from the issue. Trace how the failure message invokes the diff for large or unbounded ranges, then verify that the resulting output avoids iterating through every range element while still identifying the expected and actual boundaries.