In TortoiseSVN, patch applying does work. You need to apply the patch to the same directory as it was created from. It is always important to keep this in mind. So here's how you do it in TortoiseSVN:

Right click on the folder you want to apply the patch to. It will present a dialog asking for the location of the patch file. Select the file and this should open up a little file list window that lists the changed files, and clicking each item should open a diff window that shows what the patch is about to do to that file.

Good luck.

EDIT: Looking at the replies so far, it seems that Tortoise will only do it right if it's a file that's already versioned. That's not the case here. I need to be able to apply a patch to a file that did not come out of an SVN repository. I just tried using Tortoise because I happen to know that SVN uses diffs and has to know how to both create them and apply them.

You can install Cygwin, then use the command-line patch tool to apply the patch. See also this Unix man page, which applies to patch.

The patch tells it what file to apply to. The header should be something like (view it in Notepad or your fav text editor):

--- Folder/old_file
+++ Folder/new_file

In the case of a Subversion patch, you'd have revision numbers as well (since the file names are the same).

GNU patch will let you override those names, but I don't know of any GUI tools to do the same. I'd check with the various diff programs - though, it does not appear WinMerge supports applying patches.

Using git Diff or linux patch to apply a patch on windows using git diff

Patches created anywhere on linux, MacOS or else, using the GNU patch command or git diff can be all applied on windows using git apply.

Create the patch

For instance to create the patch from 2 directories in which 1 or more files have been changed:

diff -Naru original_dir modified_dir > 0001-path-file.patch

• "-N" treat absent files as empty, necessary to only consider modified content
• "-a" treat all files as text, not compulsory, needs removed if dealing - with binary patches.
• "-r" recursive for directories traversal
• "-u" adds 3 lines of context by default around all diffs

OR using git diff

git diff original_dir modified_dir > 0001-path-file.patch

Then copy the .patch file on the windows environment as well as the original_dir directory that contains the original unchanged files.

Apply with git diff:

• Pre-requisite: Install git, i.e. from https://git-scm.com/downloads

1 Copy the patch file in the parent directory

2 cd into the original directory

3 Apply the patch using git apply

copy 0001-path-file.patch ..\original_dir\
cd original_dir
git apply < 0001-path-file.patch

When applying patches using TortoiseSVN, I typically save the path in the root of the checked out repository. You should then be able to right click on the patch, go to the TortoiseSVN menu, and click ApplyPatch. ApplyPatch should automatically figure out which level in the directory hierarchy the patch was created.

I have, however, had issues in the past with applying patches that contain new files, or which involve renames to files. Whatever algorithm Tortoise uses for this doesn't seem to handle those scenarios very well. Unicode can give you similar issues.

If you have git install on Windows and you want to apply a patch for a git repository, you can simply do from a Windows Power Shell:

git apply ..\0001-your-patch.patch

in response to the query earlier about patch and Python 3, I got the error TypeError: can only concatenate str (not "bytes") to str

The solution for me was to change the source, in the _normalize_filenames function:

-        debug("    target = " + p.target)
-        debug("    source = " + p.source)
+        debug("    target = ", p.target)
+        debug("    source = ", p.source)

then patch worked fine for me (Python 3, Windows 10)