From a2a6d182dc27db943c886c4b863540d0f0981bd2 Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Wed, 10 May 2017 10:50:51 -0500
Subject: [PATCH] Implement tryparse(Float16, str) via Float32 conversion

---
 base/parse.jl | 2 ++
 test/parse.jl | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/base/parse.jl b/base/parse.jl
index 27c00e36dcd07..754d670f9d0b8 100644
--- a/base/parse.jl
+++ b/base/parse.jl
@@ -195,6 +195,8 @@ tryparse(::Type{Float32}, s::SubString{String}) = ccall(:jl_try_substrtof, Nulla
 
 tryparse(::Type{T}, s::AbstractString) where {T<:Union{Float32,Float64}} = tryparse(T, String(s))
 
+tryparse(::Type{Float16}, s::AbstractString) = convert(Nullable{Float16}, tryparse(Float32, s))
+
 function parse(::Type{T}, s::AbstractString) where T<:AbstractFloat
     result = tryparse(T, s)
     if isnull(result)
diff --git a/test/parse.jl b/test/parse.jl
index 5716c17491687..df2f38cfbd36f 100644
--- a/test/parse.jl
+++ b/test/parse.jl
@@ -674,6 +674,10 @@ end
 # error throwing branch from #10560
 @test_throws ArgumentError Base.tryparse_internal(Bool, "foo", 1, 2, 10, true)
 
+@test tryparse(Float64, "1.23") === Nullable(1.23)
+@test tryparse(Float32, "1.23") === Nullable(1.23f0)
+@test tryparse(Float16, "1.23") === Nullable(Float16(1.23))
+
 # PR #17393
 for op in (:.==, :.&, :.|, :.≤)
     @test parse("a $op b") == Expr(:call, op, :a, :b)