linspace: fix 32-bit failures

The issue was that doing `one(p) << p` where p is Int produces zero
on a 32-bit system if p is larger than 32, which it can be for some
Float64 arguments.

Getting tests to pass for 32-bit also required avoiding taking the
length of LinSpace objects whose lengths are 2^31 or longer. This is
a bit of a more general problem since we can represent FloatRange
and LinSpace objects whose length cannot be represented as an Int on
both 64- and 32-bit platforms, although it is, of course, easier to
encounter the problem on 32-bit systems. In fact, on 64-bit systems
it is not actually possible to construct LinSpace{Float64} objects
whose length cannot be represented as an Int. The issue does exist
for FloatRange on 64-bit systems, however. One possible solution is
to introduce length(T,x) that gives lengths in a particular type and
just define length(x) as length(Int,x) as the default behavior.

base/range.jl

@@ -200,7 +200,7 @@ function linspace{T<:FloatingPoint}(start::T, stop::T, len::T)
  s = convert(T,n*e)
  if isinf(a*n) || isinf(c*n)
  s, p = frexp(s)
- p = one(p) << p
+ p = oftype(s,2)^p
  a /= p; c /= p
  end
  if a*n/s == start && c*n/s == stop
@@ -211,7 +211,7 @@ function linspace{T<:FloatingPoint}(start::T, stop::T, len::T)
  a, c, s = start, stop, n
  if isinf(a*n) || isinf(c*n)
  s, p = frexp(s)
- p = one(p) << p
+ p = oftype(s,2)^p
  a /= p; c /= p
  end
  if a*n/s == start && c*n/s == stop

test/ranges.jl

@@ -335,13 +335,15 @@ for T = (Float32, Float64)
  @test [linspace(a,-b,3);] == [a,(a-b)/2,-b]
  for c = maxintfloat(T)-3:maxintfloat(T)
  s = linspace(-a,b,c)
- @test first(s) == -a
- @test last(s) == b
- @test length(s) == c
+ @test first(s) == -a
+ @test last(s) == b
+ c <= typemax(Int) && @test length(s) == c
+ @test s.len == c
  s = linspace(a,-b,c)
- @test first(s) == a
- @test last(s) == -b
- @test length(s) == c
+ @test first(s) == a
+ @test last(s) == -b
+ c <= typemax(Int) && @test length(s) == c
+ @test s.len == c
  end
  b = prevfloat(b)
  end