Use unsafe version of takestring more rarely

Specifically, do not use it when a value of an unknown type prints to the
buffer that is being mutated, since any user may define printing of these values
to store references to the buffer somewhere else.

base/indices.jl

@@ -132,7 +132,7 @@ function throw_promote_shape_mismatch(a::Tuple, b::Union{Nothing,Tuple}, i = not
     if i ≢ nothing
         print(msg, ", mismatch at dim ", i)
     end
-    throw(DimensionMismatch(unsafe_takestring!(msg)))
+    throw(DimensionMismatch(takestring!(msg)))
 end
 
 function promote_shape(a::Tuple{Int,}, b::Tuple{Int,})

base/io.jl

@@ -544,7 +544,7 @@ julia> rm("my_file.txt")
 """
 readuntil(filename::AbstractString, delim; kw...) = open(io->readuntil(io, delim; kw...), convert(String, filename)::String)
 readuntil(stream::IO, delim::UInt8; kw...) = _unsafe_take!(copyuntil(IOBuffer(sizehint=70), stream, delim; kw...))
-readuntil(stream::IO, delim::Union{AbstractChar, AbstractString}; kw...) = unsafe_takestring!(copyuntil(IOBuffer(sizehint=70), stream, delim; kw...))
+readuntil(stream::IO, delim::Union{AbstractChar, AbstractString}; kw...) = takestring!(copyuntil(IOBuffer(sizehint=70), stream, delim; kw...))
 readuntil(stream::IO, delim::T; keep::Bool=false) where T = _copyuntil(Vector{T}(), stream, delim, keep)
 
 
@@ -616,7 +616,7 @@ Logan
 """
 readline(filename::AbstractString; keep::Bool=false) =
     open(io -> readline(io; keep), filename)
-readline(s::IO=stdin; keep::Bool=false) = unsafe_takestring!(copyline(IOBuffer(sizehint=70), s; keep))
+readline(s::IO=stdin; keep::Bool=false) = takestring!(copyline(IOBuffer(sizehint=70), s; keep))
 
 """
     copyline(out::IO, io::IO=stdin; keep::Bool=false)

base/iostream.jl

@@ -455,7 +455,7 @@ function readuntil_string(s::IOStream, delim::UInt8, keep::Bool)
 end
 readuntil(s::IOStream, delim::AbstractChar; keep::Bool=false) =
     isascii(delim) ? readuntil_string(s, delim % UInt8, keep) :
-    unsafe_takestring!(copyuntil(IOBuffer(sizehint=70), s, delim; keep))
+    takestring!(copyuntil(IOBuffer(sizehint=70), s, delim; keep))
 
 function readline(s::IOStream; keep::Bool=false)
     @_lock_ios s ccall(:jl_readuntil, Ref{String}, (Ptr{Cvoid}, UInt8, UInt8, UInt8), s.ios, '\n', 1, keep ? 0 : 2)

base/show.jl

@@ -3158,7 +3158,7 @@ summary(io::IO, x) = print(io, typeof(x))
 function summary(x)
     io = IOBuffer()
     summary(io, x)
-    unsafe_takestring!(io)
+    takestring!(io)
 end
 
 ## `summary` for AbstractArrays

base/strings/annotated.jl

@@ -274,7 +274,7 @@ function annotatedstring(xs...)
             print(s, x)
         end
     end
-    str = unsafe_takestring!(buf)
+    str = takestring!(buf)
     AnnotatedString(str, annotations)
 end
 
@@ -457,7 +457,7 @@ function annotated_chartransform(f::Function, str::AnnotatedString, state=nothin
         stop_offset  = last(offsets[findlast(<=(stop) ∘ first, offsets)::Int])
         push!(annots, ((start + start_offset):(stop + stop_offset), value))
     end
-    AnnotatedString(unsafe_takestring!(outstr), annots)
+    AnnotatedString(takestring!(outstr), annots)
 end
 
 ## AnnotatedIOBuffer

base/strings/basic.jl

@@ -682,7 +682,7 @@ function filter(f, s::AbstractString)
     for c in s
         f(c) && write(out, c)
     end
-    unsafe_takestring!(out)
+    takestring!(out)
 end
 
 ## string first and last ##

base/strings/io.jl

@@ -113,7 +113,7 @@ function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
     else
         f(s, args...)
     end
-    unsafe_takestring!(s)
+    takestring!(s)
 end
 
 function _str_sizehint(x)
@@ -147,7 +147,7 @@ function print_to_string(xs...)
     for x in xs
         print(s, x)
     end
-    unsafe_takestring!(s)
+    takestring!(s)
 end
 
 function string_with_env(env, xs...)
@@ -164,7 +164,7 @@ function string_with_env(env, xs...)
     for x in xs
         print(env_io, x)
     end
-    unsafe_takestring!(s)
+    takestring!(s)
 end
 
 """
@@ -756,7 +756,7 @@ function unindent(str::AbstractString, indent::Int; tabwidth=8)
             print(buf, ' ')
         end
     end
-    unsafe_takestring!(buf)
+    takestring!(buf)
 end
 
 function String(a::AbstractVector{Char})

base/strings/unicode.jl

@@ -680,7 +680,7 @@ function titlecase(s::AbstractString; wordsep::Function = !isletter, strict::Boo
         end
         c0 = c
     end
-    return unsafe_takestring!(b)
+    return takestring!(b)
 end
 
 # TODO: improve performance characteristics, room for a ~10x improvement.

base/strings/util.jl

@@ -1112,5 +1112,5 @@ function Base.rest(s::AbstractString, st...)
     for c in Iterators.rest(s, st...)
         print(io, c)
     end
-    return unsafe_takestring!(io)
+    return takestring!(io)
 end

base/task.jl

@@ -95,7 +95,7 @@ function show_task_exception(io::IO, t::Task; indent = true)
     else
         show_exception_stack(IOContext(b, io), stack)
     end
-    str = unsafe_takestring!(b)
+    str = takestring!(b)
     if indent
         str = replace(str, "\n" => "\n    ")
     end

stdlib/Base64/src/encode.jl

@@ -211,6 +211,6 @@ function base64encode(f::Function, args...; context=nothing)
         f(IOContext(b, context), args...)
     end
     close(b)
-    return unsafe_takestring!(s)
+    return takestring!(s)
 end
 base64encode(args...; context=nothing) = base64encode(write, args...; context=context)

stdlib/Markdown/src/parse/util.jl

@@ -141,7 +141,7 @@ function readuntil(stream::IO, delimiter; newlines = false, match = nothing)
         while !eof(stream)
             if startswith(stream, delimiter)
                 if count == 0
-                    return unsafe_takestring!(buffer)
+                    return takestring!(buffer)
                 else
                     count -= 1
                     write(buffer, delimiter)