Revert "Should return "." for File.extname("file.") also on Windows"

We want to introduce consistency and better compatibility with unixen,
but the Windows APIs doues not have consistency fundamentally and
we can not found any logical way...

This reverts commit 61aff0cd189e67fa6f2565639ad0128fa33b88fc.

4 files changed, 15 insertions, 23 deletions

diff --git a/file.c b/file.c
index 170455ab0a..c46377b933 100644
--- a/file.c
+++ b/file.c
@@ -4711,26 +4711,13 @@ ruby_enc_find_extname(const char *name, long *len, rb_encoding *enc)
     while (*p) {
 	if (*p == '.' || istrailinggarbage(*p)) {
 #if USE_NTFS
-	    const char *first = 0, *last, *dot;
-	    if (*p == '.') first = p;
-	    last = p++;
-	    dot = last;
+	    const char *last = p++, *dot = last;
 	    while (istrailinggarbage(*p)) {
-		if (*p == '.') {
-		    dot = p;
-		    if (!first) {
-			first = p;
-		    }
-		}
+		if (*p == '.') dot = p;
 		p++;
 	    }
 	    if (!*p || isADS(*p)) {
-		if (first == dot && e == 0) {
-		    e = first;
-		}
-		else {
-		    p = last;
-		}
+		p = last;
 		break;
 	    }
 	    if (*last == '.' || dot > last) e = dot;
@@ -4779,7 +4766,8 @@ ruby_enc_find_extname(const char *name, long *len, rb_encoding *enc)
  *     File.extname("test.rb")         #=> ".rb"
  *     File.extname("a/b/d/test.rb")   #=> ".rb"
  *     File.extname(".a/b/d/test.rb")  #=> ".rb"
- *     File.extname("foo.")            #=> "."
+ *     File.extname("foo.")            #=> "" on Windows
+ *     File.extname("foo.")            #=> "." on non-Windows
  *     File.extname("test")            #=> ""
  *     File.extname(".profile")        #=> ""
  *     File.extname(".profile.sh")     #=> ".sh"
diff --git a/spec/ruby/core/file/extname_spec.rb b/spec/ruby/core/file/extname_spec.rb
index 79290960fb..e9b53bc24d 100644
--- a/spec/ruby/core/file/extname_spec.rb
+++ b/spec/ruby/core/file/extname_spec.rb
@@ -23,14 +23,14 @@ describe "File.extname" do
   end
 
   describe "for a filename ending with a dot" do
-    ruby_version_is ""..."2.7" do
+    guard -> { platform_is :windows or ruby_version_is ""..."2.7" } do
       it "returns ''" do
         File.extname(".foo.").should == ""
         File.extname("foo.").should == ""
       end
     end
 
-    ruby_version_is "2.7" do
+    guard -> { platform_is_not :windows and ruby_version_is "2.7" } do
       it "returns '.'" do
         File.extname(".foo.").should == "."
         File.extname("foo.").should == "."
diff --git a/test/ruby/test_file_exhaustive.rb b/test/ruby/test_file_exhaustive.rb
index de4c21e5ca..975bcb6bc2 100644
--- a/test/ruby/test_file_exhaustive.rb
+++ b/test/ruby/test_file_exhaustive.rb
@@ -1268,19 +1268,19 @@ class TestFileExhaustive < Test::Unit::TestCase
     infixes2 = infixes + [".ext "]
     appendixes = [""]
     if NTFS
-      appendixes << " " << [".", ".", ""] << "::$DATA" << "::$DATA.bar"
+      appendixes << " " << "." << "::$DATA" << "::$DATA.bar"
     else
       appendixes << [".", "."]
     end
     prefixes.each do |prefix|
-      appendixes.each do |appendix, ext = "", ext2 = ext|
+      appendixes.each do |appendix, ext = ""|
         infixes.each do |infix|
           path = "#{prefix}foo#{infix}#{appendix}"
           assert_equal(ext, File.extname(path), "File.extname(#{path.inspect})")
         end
         infixes2.each do |infix|
           path = "#{prefix}foo#{infix}.ext#{appendix}"
-          assert_equal(ext2.empty? ? ".ext" : appendix, File.extname(path), "File.extname(#{path.inspect})")
+          assert_equal(ext.empty? ? ".ext" : appendix, File.extname(path), "File.extname(#{path.inspect})")
         end
       end
     end
diff --git a/test/ruby/test_path.rb b/test/ruby/test_path.rb
index 64111ee805..b35e942a2a 100644
--- a/test/ruby/test_path.rb
+++ b/test/ruby/test_path.rb
@@ -239,7 +239,11 @@ class TestPath < Test::Unit::TestCase
       ext = '.'
     end
     assert_equal(ext, File.extname('a.rb.'))
-    assert_equal('.', File.extname('a.'))
+    if /mswin|bccwin|mingw/ =~ RUBY_PLATFORM
+      # trailing spaces and dots are ignored on NTFS.
+      ext = ''
+    end
+    assert_equal(ext, File.extname('a.'))
     assert_equal('', File.extname('.x'))
     assert_equal('', File.extname('..x'))
   end