sameids: fix trailing identifier highlighting

autoload/go/config_test.vim

@@ -21,7 +21,7 @@ func! Test_SetBuildTags() abort
 
     let l:expectedfilename = printf('%s/foo.go', l:dir)
 
-    let l:expected = [0, 5, 1, 0]
+    let l:expected = [0, 5, 6, 0]
     call assert_notequal(l:expected, l:jumpstart)
 
     call go#def#Jump('', 0)
@@ -57,7 +57,7 @@ func! Test_SetBuildTags() abort
     call assert_equal(l:jumpstart, getpos('.'))
 
     let l:expectedfilename = printf('%s/constrainedfoo.go', l:dir)
-    let l:expected = [0, 6, 1, 0]
+    let l:expected = [0, 6, 6, 0]
     call assert_notequal(l:expected, l:jumpstart)
 
     call go#def#Jump('', 0)

autoload/go/lsp.vim

@@ -615,7 +615,14 @@ function! s:definitionHandler(next, msg) abort dict
 
   " gopls returns a []Location; just take the first one.
   let l:msg = a:msg[0]
-  let l:args = [[printf('%s:%d:%d: %s', go#path#FromURI(l:msg.uri), l:msg.range.start.line+1, go#lsp#lsp#PositionOf(getline(l:msg.range.start.line+1), l:msg.range.start.character), 'lsp does not supply a description')]]
+
+  let l:line = s:lineinfile(go#path#FromURI(l:msg.uri), l:msg.range.start.line+1)
+  if l:line is -1
+    call go#util#Warn('could not find definition')
+    return
+  endif
+
+  let l:args = [[printf('%s:%d:%d: %s', go#path#FromURI(l:msg.uri), l:msg.range.start.line+1, go#lsp#lsp#PositionOf(l:line, l:msg.range.start.character), 'lsp does not supply a description')]]
   call call(a:next, l:args)
 endfunction
 
@@ -641,7 +648,14 @@ function! s:typeDefinitionHandler(next, msg) abort dict
 
   " gopls returns a []Location; just take the first one.
   let l:msg = a:msg[0]
-  let l:args = [[printf('%s:%d:%d: %s', go#path#FromURI(l:msg.uri), l:msg.range.start.line+1, go#lsp#lsp#PositionOf(getline(l:msg.range.start.line+1), l:msg.range.start.character), 'lsp does not supply a description')]]
+
+  let l:line = s:lineinfile(go#path#FromURI(l:msg.uri), l:msg.range.start.line+1)
+  if l:line is -1
+    call go#util#Warn('could not find definition')
+    return
+  endif
+
+  let l:args = [[printf('%s:%d:%d: %s', go#path#FromURI(l:msg.uri), l:msg.range.start.line+1, go#lsp#lsp#PositionOf(l:line, l:msg.range.start.character), 'lsp does not supply a description')]]
   call call(a:next, l:args)
 endfunction
 
@@ -2035,7 +2049,11 @@ function! s:lineinfile(fname, line) abort
     if l:bufnr == -1 || len(l:bufinfo) == 0 || l:bufinfo[0].loaded == 0
       let l:filecontents = readfile(a:fname, '', a:line)
     else
-      let l:filecontents = getbufline(a:fname, a:line)
+      if exists('*getbufoneline')
+        let l:filecontents = [getbufoneline(a:fname, a:line)]
+      else
+        let l:filecontents = getbufline(a:fname, a:line)
+      endif
     endif
 
     if len(l:filecontents) == 0

autoload/go/lsp/lsp.vim

@@ -28,17 +28,17 @@ function! s:character(line, col) abort
 endfunction
 
 " go#lsp#PositionOf returns len(content[0:units]) where units is utf-16 code
-" units. This is mostly useful for converting LSP text position to vim
-" position.
+" units. This is mostly useful for converting zero-based LSP text position to
+" vim one-based position.
 function! go#lsp#lsp#PositionOf(content, units, ...) abort
-  if a:units == 0
-    return 1
+  if len(a:content) is 0
+    return 0
   endif
 
   let l:remaining = a:units
   let l:str = ''
   for l:rune in split(a:content, '\zs')
-    if l:remaining < 0
+    if l:remaining <= 0
       break
     endif
     let l:remaining -= 1
@@ -48,7 +48,7 @@ function! go#lsp#lsp#PositionOf(content, units, ...) abort
     let l:str = l:str . l:rune
   endfor
 
-  return len(l:str)
+  return len(l:str) + 1
 endfunction
 
 function! go#lsp#lsp#SeverityToErrorType(severity) abort

autoload/go/lsp/lsp_test.vim

@@ -9,6 +9,23 @@ function! Test_PositionOf_Simple()
   call assert_equal(4, l:actual)
 endfunc
 
+function! Test_PositionOf_Start()
+  let l:str = 'abcd'
+  let l:actual = go#lsp#lsp#PositionOf(l:str, 0)
+  call assert_equal(l:actual, 1)
+  " subtract one, because PositionOf returns a one-based cursor position and
+  " while string indices are zero based.
+  call assert_equal(l:str[l:actual-1], 'a')
+endfunc
+
+function! Test_PositionOf_End()
+  let l:str = 'abcd'
+  let l:actual = go#lsp#lsp#PositionOf(l:str, 3)
+  call assert_equal(l:actual, 4)
+  " subtract one, because PositionOf returns a one-based cursor position and
+  " while string indices are zero based.
+  call assert_equal(l:str[l:actual-1], 'd')
+endfunc
 
 function! Test_PositionOf_MultiByte()
   " ⌘ is U+2318, which encodes to three bytes in utf-8 and 1 code unit in