From c79f5441da735fe0badafb475cad9733d8cf3b99 Mon Sep 17 00:00:00 2001
From: Alex Guo <chessnut@outlook.com>
Date: Mon, 20 Nov 2017 22:17:10 -0800
Subject: [PATCH 1/2] Support cygwin.

Need to convert full path in cygwin to normal paths prefixed "C:\".
Then use `fnameescape` to make things work.
---
 plugin/deoplete-rust.vim | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/plugin/deoplete-rust.vim b/plugin/deoplete-rust.vim
index 2610972..62e137d 100644
--- a/plugin/deoplete-rust.vim
+++ b/plugin/deoplete-rust.vim
@@ -35,7 +35,7 @@ function! s:jumpTo(mode, filename, line_nr, column_nr)
 
     " FIXME(SK): Throws error if buffer has been modified but changes
     " have not been written to disk yet
-    exec 'edit '.a:filename
+    exec 'keepjumps edit '.fnameescape(a:filename)
     call cursor(a:line_nr, a:column_nr)
 
     normal! zz
@@ -114,8 +114,8 @@ function! s:DeopleteRustShowDocumentation()
 
     let l:line_nr = line('.')
     let l:column_nr = col('.')
-    let l:path = expand('%:p')
-    let l:buf = tempname()
+    let l:path = s:GetFilename()
+    let l:buf = s:GetTempName()
 
     call writefile(getline(1, '$'), l:buf)
 
@@ -152,8 +152,8 @@ function! s:DeopleteRustGoToDefinition(mode)
 
     let l:line_nr = line('.')
     let l:column_nr = col('.')
-    let l:path = expand('%:p')
-    let l:buf = tempname()
+    let l:path = s:GetFilename()
+    let l:buf = s:GetTempName()
 
     call writefile(getline(1, '$'), l:buf)
 
@@ -183,6 +183,23 @@ function! s:DeopleteRustGoToDefinition(mode)
     endfor
 endfunction
 
+function! s:GetFilename()
+    return s:CygwinConvertPath(expand('%:p'))
+endfunction
+
+function! s:GetTempName()
+    return s:CygwinConvertPath(tempname())
+endfunction
+
+" Returns the filename. Handles cygwin as a special case.
+function! s:CygwinConvertPath(str)
+    if has('win32unix')
+        let res = system("cygpath --windows ".a:str)
+        return fnameescape(substitute(res, '\n\+$', '', ''))
+    endif
+    return a:str
+endfunction
+
 function! s:warn(message)
     echohl WarningMsg | echomsg a:message | echohl NONE
 endfunction

From 2cf52647788e71b753601e390f659f90c5b5fa2b Mon Sep 17 00:00:00 2001
From: Alex Guo <chessnut@outlook.com>
Date: Mon, 20 Nov 2017 23:33:40 -0800
Subject: [PATCH 2/2] Add cygwin support for completion.

Previous commit was just for the vim files.
---
 rplugin/python3/deoplete/sources/rust.py | 36 +++++++++++++++++++++---
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/rplugin/python3/deoplete/sources/rust.py b/rplugin/python3/deoplete/sources/rust.py
index 5664f3d..8c5db2b 100644
--- a/rplugin/python3/deoplete/sources/rust.py
+++ b/rplugin/python3/deoplete/sources/rust.py
@@ -4,6 +4,7 @@
 import re
 import subprocess
 import tempfile
+import platform
 
 from .base import Base
 from deoplete.logger import getLogger
@@ -14,7 +15,6 @@
 VAR_RUST_SOURCE = 'deoplete#sources#rust#rust_source_path'
 VAR_DUPLICATION = 'deoplete#sources#rust#show_duplicates'
 
-
 class Source(Base):
     """Deoplete Rust source"""
     def __init__(self, vim):
@@ -81,20 +81,48 @@ def __retrieve(self):
                 'complete',
                 str(line),
                 str(column),
-                content.name,
-                buf.name
+                self.__escape_path(content.name),
+                self.__escape_path(buf.name)
             ]
 
             results = []
 
             try:
-                results = subprocess.check_output(args) \
+                # NOTE: needs to avoid the list form of calling 'check_output'
+                # because quotes was NOT preserved. See StackOverlow post.
+                # https://stackoverflow.com/a/39096422/3325787
+                cmd = " ".join(args)
+                results = subprocess.check_output(cmd, shell=True) \
                     .decode(self.__encoding).splitlines()
             except Exception:
                 pass
 
             return results
 
+    def __escape_path(self, path):
+        """
+        Handles Cygwin case.
+
+        path(String): path to escape.
+        Returns: string of new path to use.
+        """
+        if "cygwin" not in platform.system().lower():
+            return path
+        args = [
+            "cygpath", "--windows", path
+        ]
+        try:
+            results = subprocess.check_output(args) \
+                .decode(self.__encoding).splitlines()
+        except Exception:
+            pass
+        # In the error path, best-effort is to try 'path'.
+        if results is None or len(results) == 0:
+          return path
+        # TODO: find something like vim's fnameescape instead of just
+        # surrounding with quotes.
+        return '"' + results[0] + '"'
+
     def __check_binary(self):
         """Missing"""
         return os.path.isfile(self.__racer) and os.environ.get('RUST_SRC_PATH')