Don't assume that SubString has pointer and copy instead

Project.toml

@@ -7,8 +7,6 @@ version = "1.0.0-DEV"
 Serialization = "1.0"
 julia = "1.0"
 
-[deps]
-
 [extras]
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
 Serialization = "9e88b42a-f829-5b0c-bbe9-9e923198166b"

src/parse_stream.jl

@@ -391,7 +391,7 @@ function ParseStream(text::String, index::Integer=1; version=VERSION)
     ParseStream(unsafe_wrap(Vector{UInt8}, text),
                 text, index, version)
 end
-function ParseStream(text::SubString, index::Integer=1; version=VERSION)
+function ParseStream(text::SubString{String}, index::Integer=1; version=VERSION)
     # See also IOBuffer(SubString("x"))
     ParseStream(unsafe_wrap(Vector{UInt8}, pointer(text), sizeof(text)),
                 text, index, version)

test/parse_stream.jl

@@ -7,7 +7,8 @@ using JuliaSyntax: ParseStream,
     peek, peek_token,
     bump, bump_trivia, bump_invisible,
     emit, emit_diagnostic, TRIVIA_FLAG, INFIX_FLAG,
-    ParseStreamPosition, first_child_position, last_child_position
+    ParseStreamPosition, first_child_position, last_child_position,
+    parsestmt
 
 # Here we manually issue parse events in the order the Julia parser would issue
 # them
@@ -147,3 +148,81 @@ end
     @test first_child_position(st, position(st)) == ParseStreamPosition(4, 1)
     @test last_child_position(st, position(st)) == ParseStreamPosition(7, 2)
 end
+
+# This is coppied from InlineStrings.jl instead of depending
+# on InlineStrings for compat with Julia 1.2 and earlier:
+primitive type String3 <: AbstractString 4*8 end
+Base.ncodeunits(x::String3) = Int(Base.trunc_int(UInt8, x))
+function Base.codeunit(x::T, i::Int) where {T <: String3}
+    @boundscheck checkbounds(Bool, x, i) || throw(BoundsError(x, i))
+    return Base.trunc_int(UInt8, Base.lshr_int(x, 8 * (sizeof(T) - i)))
+end
+function Base.String(x::T) where {T <: String3}
+    len = ncodeunits(x)
+    out = Base._string_n(len)
+    ref = Ref{T}(_bswap(x))
+    GC.@preserve ref out begin
+        ptr = convert(Ptr{UInt8}, Base.unsafe_convert(Ptr{T}, ref))
+        unsafe_copyto!(pointer(out), ptr, len)
+    end
+    return out
+end
+function Base.isvalid(x::String3, i::Int)
+    @boundscheck checkbounds(Bool, x, i) || throw(BoundsError(x, i))
+    return @inbounds thisind(x, i) == i
+end
+function Base.thisind(s::String3, i::Int)
+    i == 0 && return 0
+    n = ncodeunits(s)
+    i == n + 1 && return i
+    @boundscheck Base.between(i, 1, n) || throw(BoundsError(s, i))
+    @inbounds b = codeunit(s, i)
+    (b & 0xc0 == 0x80) & (i-1 > 0) || return i
+    @inbounds b = codeunit(s, i-1)
+    Base.between(b, 0b11000000, 0b11110111) && return i-1
+    (b & 0xc0 == 0x80) & (i-2 > 0) || return i
+    @inbounds b = codeunit(s, i-2)
+    Base.between(b, 0b11100000, 0b11110111) && return i-2
+    (b & 0xc0 == 0x80) & (i-3 > 0) || return i
+    @inbounds b = codeunit(s, i-3)
+    Base.between(b, 0b11110000, 0b11110111) && return i-3
+    return i
+end
+Base.@propagate_inbounds function Base.iterate(s::String3, i::Int=firstindex(s))
+    (i % UInt) - 1 < ncodeunits(s) || return nothing
+    b = @inbounds codeunit(s, i)
+    u = UInt32(b) << 24
+    Base.between(b, 0x80, 0xf7) || return reinterpret(Char, u), i+1
+    return iterate_continued(s, i, u)
+end
+function iterate_continued(s::String3, i::Int, u::UInt32)
+    u < 0xc0000000 && (i += 1; @goto ret)
+    n = ncodeunits(s)
+    # first continuation byte
+    (i += 1) > n && @goto ret
+    @inbounds b = codeunit(s, i)
+    b & 0xc0 == 0x80 || @goto ret
+    u |= UInt32(b) << 16
+    # second continuation byte
+    ((i += 1) > n) | (u < 0xe0000000) && @goto ret
+    @inbounds b = codeunit(s, i)
+    b & 0xc0 == 0x80 || @goto ret
+    u |= UInt32(b) << 8
+    # third continuation byte
+    ((i += 1) > n) | (u < 0xf0000000) && @goto ret
+    @inbounds b = codeunit(s, i)
+    b & 0xc0 == 0x80 || @goto ret
+    u |= UInt32(b); i += 1
+@label ret
+    return reinterpret(Char, u), i
+end
+# End coppied from InlineStrings.jl
+
+@testset "SubString{String3} (issue #505)" begin
+    x = reinterpret(String3, 0x31203203)
+    @test x == "1 2"
+    y = split(x)[1]
+    @test y == "1"
+    @test ParseStream(y) isa ParseStream
+    @test parsestmt(Expr, y) == parsestmt(Expr, "1")
+end