From 58bdac3aa431eb67b8809bdad8f56c32c115de06 Mon Sep 17 00:00:00 2001
From: Milan Bouchet-Valat <nalimilan@club.fr>
Date: Mon, 29 Feb 2016 19:58:20 +0100
Subject: [PATCH] Implement checked operations on Bool

Bool behaves almost like unsigned integers, but with special cases
for checked_add() and checked_sub() which require adding methods
and testing separately.
---
 base/checked.jl |  6 +++++-
 test/checked.jl | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/base/checked.jl b/base/checked.jl
index a5fef27089e44..217f800e06b84 100644
--- a/base/checked.jl
+++ b/base/checked.jl
@@ -38,7 +38,7 @@ checked_mod{T<:Integer}(x::T, y::T) = no_op_err("checked_mod", T)
 checked_cld{T<:Integer}(x::T, y::T) = no_op_err("checked_cld", T)
 
 typealias SignedInt Union{Int8,Int16,Int32,Int64,Int128}
-typealias UnsignedInt Union{UInt8,UInt16,UInt32,UInt64,UInt128}
+typealias UnsignedInt Union{UInt8,UInt16,UInt32,UInt64,UInt128,Bool}
 
 # LLVM has several code generation bugs for checked integer arithmetic (see e.g.
 # #4905). We thus distinguish between operations that can be implemented via
@@ -166,6 +166,8 @@ function checked_add{T<:BrokenUnsignedInt}(x::T, y::T)
     x + y
 end
 end
+checked_add(x::Bool, y::Bool) = x + y
+checked_add(x::Bool) = +x
 
 # Handle multiple arguments
 checked_add(x) = x
@@ -212,6 +214,8 @@ function checked_sub{T<:BrokenUnsignedInt}(x::T, y::T)
     x - y
 end
 end
+checked_sub(x::Bool, y::Bool) = x - y
+checked_sub(x::Bool) = -x
 
 """
     Base.checked_mul(x, y)
diff --git a/test/checked.jl b/test/checked.jl
index f685c5c724376..9d8cfa87d1c85 100644
--- a/test/checked.jl
+++ b/test/checked.jl
@@ -196,6 +196,50 @@ for T in (UInt8, UInt16, UInt32, UInt64, UInt128)
     @test_throws DivideError checked_cld(typemax(T), T(0))
 end
 
+# Boolean
+@test checked_add(false) === 0
+@test checked_add(true) === 1
+@test checked_sub(false) === 0
+@test checked_sub(true) === -1
+@test checked_neg(false) === 0
+@test checked_neg(true) === -1
+@test checked_abs(true) === true
+@test checked_abs(false) === false
+@test checked_mul(false) === false
+@test checked_mul(true) === true
+
+@test checked_add(true, true) === 2
+@test checked_add(true, false) === 1
+@test checked_add(false, false) === 0
+@test checked_add(false, true) === 1
+
+@test checked_sub(true, true) === 0
+@test checked_sub(true, false) === 1
+@test checked_sub(false, false) === 0
+@test checked_sub(false, true) === -1
+
+@test checked_mul(true, false) === false
+@test checked_mul(false, false) === false
+@test checked_mul(true, true) === true
+@test checked_mul(false, true) === false
+
+@test checked_div(true, true) === true
+@test checked_div(false, true) === false
+@test_throws DivideError checked_div(true, false)
+@test checked_rem(true, true) === false
+@test checked_rem(false, true) === false
+@test_throws DivideError checked_rem(true, false)
+@test checked_fld(true, true) === true
+@test checked_fld(false, true) === false
+@test_throws DivideError checked_fld(true, false)
+@test checked_mod(true, true) === false
+@test checked_mod(false, true) === false
+@test_throws DivideError checked_mod(true, false)
+@test checked_cld(true, true) === true
+@test checked_cld(false, true) === false
+@test_throws DivideError checked_cld(true, false)
+
+# BigInt
 @test checked_abs(BigInt(-1)) == BigInt(1)
 @test checked_abs(BigInt(1)) == BigInt(1)
 @test checked_neg(BigInt(-1)) == BigInt(1)