make tempname on windows match unix behavior. fixes #9053 (#25530)

also deprecate `tempname(::UInt32)` and add a warning to the docs.

NEWS.md

@@ -385,6 +385,9 @@ This section lists changes that do not have deprecation warnings.
       to get the old behavior (only "space" characters are considered as
       word separators), use the keyword `wordsep=isspace`.
 
+  * The `tempname` function used to create a file on Windows but not on other
+    platforms. It now never creates a file ([#9053]).
+
 Library improvements
 --------------------
 
@@ -1194,4 +1197,4 @@ Command-line option changes
 [#25231]: https://github.com/JuliaLang/julia/issues/25231
 [#25365]: https://github.com/JuliaLang/julia/issues/25365
 [#25424]: https://github.com/JuliaLang/julia/issues/25424
-[#25532]: https://github.com/JuliaLang/julia/issues/25532
+[#25532]: https://github.com/JuliaLang/julia/issues/25532

base/deprecated.jl

@@ -2789,6 +2789,13 @@ end
 @deprecate findn(x::AbstractMatrix) (I = find(!iszero, x); (getindex.(I, 1), getindex.(I, 2)))
 @deprecate findn(a::AbstractArray{T, N}) where {T, N} (I = find(!iszero, x); ntuple(i -> getindex.(I, i), N))
 
+# issue #9053
+if Sys.iswindows()
+function Filesystem.tempname(uunique::UInt32)
+    error("`tempname(::UInt32)` is discontinued.")
+end
+end
+
 # END 0.7 deprecations
 
 # BEGIN 1.0 deprecations

base/file.jl

@@ -265,9 +265,9 @@ function tempdir()
     resize!(temppath,lentemppath)
     return transcode(String, temppath)
 end
-tempname(uunique::UInt32=UInt32(0)) = tempname(tempdir(), uunique)
+
 const temp_prefix = cwstring("jl_")
-function tempname(temppath::AbstractString,uunique::UInt32)
+function _win_tempname(temppath::AbstractString, uunique::UInt32)
     tempp = cwstring(temppath)
     tname = Vector{UInt16}(uninitialized, 32767)
     uunique = ccall(:GetTempFileNameW,stdcall,UInt32,(Ptr{UInt16},Ptr{UInt16},UInt32,Ptr{UInt16}), tempp,temp_prefix,uunique,tname)
@@ -280,7 +280,7 @@ function tempname(temppath::AbstractString,uunique::UInt32)
 end
 
 function mktemp(parent=tempdir())
-    filename = tempname(parent, UInt32(0))
+    filename = _win_tempname(parent, UInt32(0))
     return (filename, Base.open(filename, "r+"))
 end
 
@@ -290,7 +290,7 @@ function mktempdir(parent=tempdir())
         if (seed & typemax(UInt16)) == 0
             seed += 1
         end
-        filename = tempname(parent, seed)
+        filename = _win_tempname(parent, seed)
         ret = ccall(:_wmkdir, Int32, (Ptr{UInt16},), cwstring(filename))
         if ret == 0
             return filename
@@ -300,6 +300,21 @@ function mktempdir(parent=tempdir())
     end
 end
 
+function tempname()
+    parent = tempdir()
+    seed::UInt32 = rand(UInt32)
+    while true
+        if (seed & typemax(UInt16)) == 0
+            seed += 1
+        end
+        filename = _win_tempname(parent, seed)
+        if !ispath(filename)
+            return filename
+        end
+        seed += 1
+    end
+end
+
 else # !windows
 # Obtain a temporary filename.
 function tempname()
@@ -343,7 +358,14 @@ tempdir()
 """
     tempname()
 
-Generate a unique temporary file path.
+Generate a temporary file path. This function only returns a path; no file is
+created. The path is likely to be unique, but this cannot be guaranteed.
+
+!!! warning
+
+    This can lead to race conditions if another process obtains the same
+    file name and creates the file before you are able to.
+    Using [`mktemp()`](@ref) is recommended instead.
 """
 tempname()
 

base/pkg/entry.jl

@@ -633,19 +633,13 @@ function build!(pkgs::Vector, seen::Set, errfile::AbstractString)
 end
 
 function build!(pkgs::Vector, errs::Dict, seen::Set=Set())
-    errfile = tempname()
-    touch(errfile)  # create empty file
-    try
+    mktemp() do errfile, f
         build!(pkgs, seen, errfile)
-        open(errfile, "r") do f
-            while !eof(f)
-                pkg = deserialize(f)
-                err = deserialize(f)
-                errs[pkg] = err
-            end
+        while !eof(f)
+            pkg = deserialize(f)
+            err = deserialize(f)
+            errs[pkg] = err
         end
-    finally
-        isfile(errfile) && Base.rm(errfile)
     end
 end
 

test/file.jl

@@ -218,10 +218,10 @@ close(s)
 my_tempdir = tempdir()
 @test isdir(my_tempdir) == true
 
-path = tempname()
-# Issue #9053.
-@test ispath(path) == Sys.iswindows()
-ispath(path) && rm(path)
+let path = tempname()
+    # issue #9053
+    @test !ispath(path)
+end
 
 (p, f) = mktemp()
 print(f, "Here is some text")

test/replcompletions.jl

@@ -776,6 +776,7 @@ end
 
 if Sys.iswindows()
     tmp = tempname()
+    touch(tmp)
     path = dirname(tmp)
     file = basename(tmp)
     temp_name = basename(path)