From 16516b5fbf8edd00ce848daf6b4c0d811a4828f5 Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Mon, 17 Sep 2018 08:51:29 -0400
Subject: [PATCH] =?UTF-8?q?fix=20digits(n::Unsigned)=20with=20neg=20base?=
 =?UTF-8?q?=20for=20`n=20>=20typemax(n)=C3=B72`=20(#29205)?=
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Alternative based on https://github.com/JuliaLang/julia/pull/29187

Tests from rforquet's PR linked above.
---
 base/intfuncs.jl | 24 ++++++++++++++++--------
 test/intfuncs.jl |  9 ++++++++-
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/base/intfuncs.jl b/base/intfuncs.jl
index a6f6ea05efe41..8b9f3d441ec01 100644
--- a/base/intfuncs.jl
+++ b/base/intfuncs.jl
@@ -744,17 +744,25 @@ julia> digits!([2,2,2,2,2,2], 10, base = 2)
 ```
 """
 function digits!(a::AbstractVector{T}, n::Integer; base::Integer = 10) where T<:Integer
-    base < 0 && isa(n, Unsigned) && return digits!(a, convert(Signed, n), base = base)
     2 <= abs(base) || throw(ArgumentError("base must be ≥ 2 or ≤ -2, got $base"))
     hastypemax(T) && abs(base) - 1 > typemax(T) &&
         throw(ArgumentError("type $T too small for base $base"))
-    for i in eachindex(a)
-        if base > 0
-            a[i] = rem(n, base)
-            n = div(n, base)
-        else
-            a[i] = mod(n, -base)
-            n = cld(n, base)
+    isempty(a) && return a
+
+    if base > 0
+        for i in eachindex(a)
+            n, d = divrem(n, base)
+            a[i] = d
+        end
+    else
+        # manually peel one loop iteration for type stability
+        n, d = fldmod(n, -base)
+        a[firstindex(a)] = d
+        n = -signed(n)
+        for i in firstindex(a)+1:lastindex(a)
+            n, d = fldmod(n, -base)
+            a[i] = d
+            n = -n
         end
     end
     return a
diff --git a/test/intfuncs.jl b/test/intfuncs.jl
index b060bc69686b2..37033bde31fa4 100644
--- a/test/intfuncs.jl
+++ b/test/intfuncs.jl
@@ -179,11 +179,18 @@ end
     @test digits(5, base = 3) == [2, 1]
 
     @testset "digits/base with negative bases" begin
-        @testset "digits(n::$T, base = b)" for T in (Int, UInt, BigInt, Int32)
+        @testset "digits(n::$T, base = b)" for T in (Int, UInt, BigInt, Int32, UInt32)
             @test digits(T(8163), base = -10) == [3, 4, 2, 2, 1]
             if !(T<:Unsigned)
                 @test digits(T(-8163), base = -10) == [7, 7, 9, 9]
             end
+            if T !== BigInt
+                b = rand(-32:-2)
+                for n = T[rand(T), typemax(T), typemin(T)]
+                    # issue #29183
+                    @test digits(n, base=b) == digits(signed(widen(n)), base=b)
+                end
+            end
         end
         @test [string(n, base = b)
                for n = [-10^9, -10^5, -2^20, -2^10, -100, -83, -50, -34, -27, -16, -7, -3, -2, -1,