Fix JuliaLang#31368: joinpath works on collections of paths (JuliaLan…

…g#38263)

* Fix JuliaLang#31368: joinpath works on collections of paths

* Update base/path.jl

Co-authored-by: Jameson Nash <vtjnash@gmail.com>

* Apply suggestions from code review

* Fixup

Co-authored-by: Mustafa M <mus-m@outlook.com>
Co-authored-by: Jameson Nash <vtjnash@gmail.com>

base/path.jl

@@ -254,16 +254,19 @@ function splitpath(p::String)
     return out
 end
 
-joinpath(path::AbstractString)::String = path
-
 if Sys.iswindows()
 
-function joinpath(path::AbstractString, paths::AbstractString...)::String
-    result_drive, result_path = splitdrive(path)
+function joinpath(paths::Union{Tuple, AbstractVector})::String
+    assertstring(x) = x isa AbstractString || throw(ArgumentError("path component is not a string: $(repr(x))"))
+
+    isempty(paths) && throw(ArgumentError("collection of path components must be non-empty"))
+    assertstring(paths[1])
+    result_drive, result_path = splitdrive(paths[1])
 
-    local p_drive, p_path
-    for p in paths
-        p_drive, p_path = splitdrive(p)
+    p_path = ""
+    for i in firstindex(paths)+1:lastindex(paths)
+        assertstring(paths[i])
+        p_drive, p_path = splitdrive(paths[i])
 
         if startswith(p_path, ('\\', '/'))
             # second path is absolute
@@ -299,8 +302,15 @@ end
 
 else
 
-function joinpath(path::AbstractString, paths::AbstractString...)::String
-    for p in paths
+function joinpath(paths::Union{Tuple, AbstractVector})::String
+    assertstring(x) = x isa AbstractString || throw(ArgumentError("path component is not a string: $(repr(x))"))
+
+    isempty(paths) && throw(ArgumentError("collection of path components must be non-empty"))
+    assertstring(paths[1])
+    path = paths[1]
+    for i in firstindex(paths)+1:lastindex(paths)
+        p = paths[i]
+        assertstring(p)
         if isabspath(p)
             path = p
         elseif isempty(path) || path[end] == '/'
@@ -314,8 +324,12 @@ end
 
 end # os-test
 
+joinpath(paths::AbstractString...)::String = joinpath(paths)
+
 """
     joinpath(parts::AbstractString...) -> String
+    joinpath(parts::Vector{AbstractString}) -> String
+    joinpath(parts::Tuple{AbstractString}) -> String
 
 Join path components into a full path. If some argument is an absolute path or
 (on Windows) has a drive specification that doesn't match the drive computed for
@@ -331,6 +345,11 @@ letter casing, hence `joinpath("C:\\A","c:b") = "C:\\A\\b"`.
 julia> joinpath("/home/myuser", "example.jl")
 "/home/myuser/example.jl"
 ```
+
+```jldoctest
+julia> joinpath(["/home/myuser", "example.jl"])
+"/home/myuser/example.jl"
+```
 """
 joinpath
 

test/path.jl

@@ -59,6 +59,11 @@
         @test joinpath(S("foo"), S(homedir())) == homedir()
         @test joinpath(S(abspath("foo")), S(homedir())) == homedir()
 
+        for str in map(S, [sep, "a$(sep)b", "a$(sep)b$(sep)c", "a$(sep)b$(sep)c$(sep)d"])
+            @test str == joinpath(splitpath(str))
+            @test joinpath(splitpath(str)) == joinpath(splitpath(str)...)
+        end
+
         if Sys.iswindows()
             @test joinpath(S("foo"),S("bar:baz")) == "bar:baz"
             @test joinpath(S("C:"),S("foo"),S("D:"),S("bar")) == "D:bar"
@@ -75,6 +80,11 @@
             @test joinpath(S("\\\\server\\share"),S("a")) == "\\\\server\\share\\a"
             @test joinpath(S("\\\\server\\share\\"), S("a")) == "\\\\server\\share\\a"
 
+            for str in map(S, ["c:\\", "c:\\a", "c:\\a\\b", "c:\\a\\b\\c", "c:\\a\\b\\c\\d"])
+                @test str == joinpath(splitpath(str))
+                @test joinpath(splitpath(str)) == joinpath(splitpath(str)...)
+            end
+
         elseif Sys.isunix()
             @test joinpath(S("foo"),S("bar:baz")) == "foo$(sep)bar:baz"
             @test joinpath(S("C:"),S("foo"),S("D:"),S("bar")) == "C:$(sep)foo$(sep)D:$(sep)bar"