Fix #6262

Use an Int for the accumulation variable when iterating over integer
types smaller than Int, and the type of the range when iterating over
types larger than Int

base/range.jl

@@ -53,18 +53,15 @@ colon{T<:Integer}(start::T, stop::T) =
     Range1{T}(start, ifelse(stop<start, 0, int(stop-start+1)))
 
 if Int === Int32
-colon{T<:Union(Int8,Int16,Int32,Uint8,Uint16)}(start::T, stop::T) =
-    Range1{T}(start,
-              ifelse(stop < start, 0,
-                     checked_add(checked_sub(convert(Int,stop),convert(Int,start)),1)),
-              0)  # hack to elide negative length check
+    eval(:(typealias SmallInteger Union(Int8,Int16,Int32,Uint8,Uint16)))
 else
-colon{T<:Union(Int8,Int16,Int32,Int64,Uint8,Uint16,Uint32)}(start::T, stop::T) =
+    eval(:(typealias SmallInteger Union(Int8,Int16,Int32,Int64,Uint8,Uint16,Uint32)))
+end
+colon{T<:SmallInteger}(start::T, stop::T) =
     Range1{T}(start,
               ifelse(stop < start, 0,
                      checked_add(checked_sub(convert(Int,stop),convert(Int,start)),1)),
               0)  # hack to elide negative length check
-end
 
 function colon{T<:Real}(start::T, step::T, stop::T)
     step != 0 || error("step cannot be zero in colon syntax")
@@ -238,6 +235,9 @@ done(r::Ranges, i) = (length(r) <= i)
 
 # though these look very similar to the above, for some reason LLVM generates
 # much better code for these.
+start{T<:SmallInteger}(r::Range1{T}) = int(r.start)
+next{T<:SmallInteger}(r::Range1{T}, i) = (oftype(T, i), i+1)
+done{T<:SmallInteger}(r::Range1{T}, i) = i==r.start+r.len
 start{T<:Integer}(r::Range1{T}) = r.start
 next{T<:Integer}(r::Range1{T}, i) = (i, oftype(T, i+1))
 done{T<:Integer}(r::Range1{T}, i) = i==oftype(T, r.start+r.len)

test/ranges.jl

@@ -149,6 +149,36 @@ let s = 0
         @test s <= 2
     end
     @test s == 2
+
+    # loops covering the full range of smaller integer types
+    s = 0
+    for i = typemin(Uint8):typemax(Uint8)
+        s += 1
+    end
+    @test s == 256
+
+    # loops past typemax(Int)
+    n = 0
+    s = int128(0)
+    for i = typemax(Uint64)-2:typemax(Uint64)
+        n += 1
+        s += i
+    end
+    @test n == 3
+    @test s == 3*int128(typemax(Uint64)) - 3
+
+    # loops over empty ranges
+    s = 0
+    for i = 0xff:0x00
+        s += 1
+    end
+    @test s == 0
+
+    s = 0
+    for i = int128(typemax(Int128)):int128(typemin(Int128))
+        s += 1
+    end
+    @test s == 0
 end
 
 # sums (see #5798)
@@ -160,7 +190,7 @@ else
     @test sum(int64(1:10^9-1)) == div(10^9 * (int64(10^9)-1), 2)
 end
 
-# with ranges
+# operations between ranges and arrays
 @test all(([1:5] + (5:-1:1)) .== 6)
 @test all(((5:-1:1) + [1:5]) .== 6)
 @test all(([1:5] - (1:5)) .== 0)