Rustup rust src heuristics

Author: bstaletic

ycmd/completers/rust/rust_completer.py

@@ -22,7 +22,8 @@
 # Not installing aliases from python-future; it's unreliable and slow.
 from builtins import *  # noqa
 
-from ycmd.utils import ToBytes, SetEnviron, ProcessIsRunning, urljoin
+from ycmd.utils import ( FindExecutable, ToUnicode, ToBytes, SetEnviron,
+                         ProcessIsRunning, urljoin )
 from ycmd.completers.completer import Completer
 from ycmd import responses, utils, hmac_utils
 
@@ -35,6 +36,7 @@
 import binascii
 import threading
 import os
+import subprocess
 
 from os import path as p
 
@@ -66,6 +68,16 @@
 LOGFILE_FORMAT = 'racerd_{port}_{std}_'
 
 
+def _GetRustSysroot( rustc_exec ):
+  return ToUnicode( utils.SafePopen( [ rustc_exec,
+                                        '--print',
+                                        'sysroot' ],
+                                      stdin_windows = subprocess.PIPE,
+                                      stdout = subprocess.PIPE,
+                                      stderr = subprocess.PIPE )
+                              .communicate()[ 0 ].rstrip() )
+
+
 def FindRacerdBinary( user_options ):
   """
   Find path to racerd binary
@@ -127,13 +139,28 @@ def _GetRustSrcPath( self ):
     """
     Attempt to read user option for rust_src_path. Fallback to environment
     variable if it's not provided.
+    Finally try to be smart and figure out the path assuming the user set up
+    rust by the means of rustup.
     """
     rust_src_path = ( self.user_options[ 'rust_src_path' ] or
                       os.environ.get( 'RUST_SRC_PATH' ) )
 
     if rust_src_path:
       return os.path.expanduser( os.path.expandvars( rust_src_path ) )
-    return None
+
+    # Try to figure out the src path using rustup
+    rustc_executable = FindExecutable( 'rustc' )
+    if not rustc_executable:
+      return None
+
+    rust_sysroot = _GetRustSysroot( rustc_executable )
+    rust_src_path = p.join( rust_sysroot,
+                            'lib',
+                            'rustlib',
+                            'src',
+                            'rust',
+                            'src' )
+    return rust_src_path if p.isdir( rust_src_path ) else None
 
 
   def SupportedFiletypes( self ):

ycmd/tests/rust/get_completions_test.py

@@ -54,9 +54,12 @@ def GetCompletions_Basic_test( app ):
                           CompletionEntryMatcher( 'build_shuttle' ) ) )
 
 
-@SharedYcmd
+@IsolatedYcmd()
+@patch( 'ycmd.completers.rust.rust_completer._GetRustSysroot',
+        return_value = '/non/existing/rust/src/path' )
 def GetCompletions_WhenStandardLibraryCompletionFails_MentionRustSrcPath_test(
-  app ):
+  app, *args ):
+  WaitUntilCompleterServerReady( app, 'rust' )
   filepath = PathToTestFile( 'std_completions.rs' )
   contents = ReadFile( filepath )
 
@@ -74,8 +77,11 @@ def GetCompletions_WhenStandardLibraryCompletionFails_MentionRustSrcPath_test(
                ErrorMatcher( RuntimeError, ERROR_FROM_RACERD_MESSAGE ) )
 
 
-@SharedYcmd
-def GetCompletions_WhenNoCompletionsFound_MentionRustSrcPath_test( app ):
+@IsolatedYcmd()
+@patch( 'ycmd.completers.rust.rust_completer._GetRustSysroot',
+        return_value = '/non/existing/rust/src/path' )
+def GetCompletions_WhenNoCompletionsFound_MentionRustSrcPath_test( app, *args ):
+  WaitUntilCompleterServerReady( app, 'rust' )
   filepath = PathToTestFile( 'test.rs' )
   contents = ReadFile( filepath )
 
@@ -132,3 +138,41 @@ def GetCompletions_NonExistingRustSrcPathFromEnvironmentVariable_test( app ):
   assert_that( response,
                ErrorMatcher( RuntimeError,
                              NON_EXISTING_RUST_SOURCES_PATH_MESSAGE ) )
+
+
+@IsolatedYcmd()
+@patch( 'ycmd.completers.rust.rust_completer.FindExecutable',
+        return_value = None )
+def GetCompletions_WhenRustcNotFound_MentionRustSrcPath_test( app, *args ):
+  WaitUntilCompleterServerReady( app, 'rust' )
+  filepath = PathToTestFile( 'test.rs' )
+  contents = ReadFile( filepath )
+
+  completion_data = BuildRequest( filepath = filepath,
+                                  filetype = 'rust',
+                                  contents = contents,
+                                  force_semantic = True,
+                                  line_num = 1,
+                                  column_num = 1 )
+
+  response = app.post_json( '/completions',
+                            completion_data,
+                            expect_errors = True ).json
+  assert_that( response,
+               ErrorMatcher( RuntimeError, ERROR_FROM_RACERD_MESSAGE ) )
+
+
+@IsolatedYcmd()
+@patch( 'ycmd.completers.rust.rust_completer._GetRustSysroot',
+        return_value = PathToTestFile( 'rustup-toolchain' ) )
+def GetCompletions_RustupPathHeuristics_test( app, *args ):
+  request_data = BuildRequest( filetype = 'rust' )
+
+  assert_that( app.post_json( '/debug_info', request_data ).json,
+               has_entry( 'completer', has_entry( 'items', has_items(
+                 has_entry( 'value', PathToTestFile( 'rustup-toolchain',
+                                                     'lib',
+                                                     'rustlib',
+                                                     'src',
+                                                     'rust',
+                                                     'src' ) ) ) ) ) )