textobj: include function variable for anonymous functions

fixes #1181

autoload/go/textobj.vim

@@ -6,6 +6,10 @@ if !exists("g:go_textobj_include_function_doc")
   let g:go_textobj_include_function_doc = 1
 endif
 
+if !exists("g:go_textobj_include_variable")
+  let g:go_textobj_include_variable = 1
+endif
+
 " ( ) motions
 " { } motions
 " s for sentence
@@ -60,6 +64,16 @@ function! go#textobj#Function(mode) abort
     " want's to include doc comments for function declarations
     if has_key(info, 'doc') && g:go_textobj_include_function_doc
       call cursor(info.doc.line, info.doc.col)
+    elseif info['sig']['name'] == '' && g:go_textobj_include_variable
+      " one liner anonymous functions
+      if info.lbrace.line == info.rbrace.line
+        " jump to first nonblack char, to get the correct column
+        call cursor(info.lbrace.line, 0 )
+        normal! ^
+        call cursor(info.func.line, col("."))
+      else
+        call cursor(info.func.line, info.rbrace.col)
+      endif
     else
       call cursor(info.func.line, info.func.col)
     endif

doc/vim-go.txt

@@ -981,6 +981,8 @@ af            "a function", select contents from a function definition to the
                closing bracket. If |'g:go_textobj_include_function_doc'| is
                enabled it also includes the comment doc for a function
                declaration. This text-object also supports literal functions.
+               If |'g:go_textobj_include_variable'| is enabled it also
+               includes the variable of an function assignment
 
                                                *go-v_if* *go-if*
 if            "inside a function", select contents of a function,
@@ -1348,6 +1350,13 @@ Consider the comment above a function to be part of the function when using
 the `af` text object and `[[` motion. By default it's enabled. >
 
   let g:go_textobj_include_function_doc = 1
+<
+                                             *'g:go_textobj_include_variable'*
+
+Consider the variable of an function assignment to be part of the anonymous
+function when using the `af` text object. By default it's enabled. >
+
+  let g:go_textobj_include_variable = 1
 <
                                                   *'g:go_metalinter_autosave'*