vim-patch:8.1.1356: some text in heredoc assignment ends the text

Problem:    Some text in heredoc assignment ends the text. (Ozaki Kiichi)
Solution:   Recognize "let v =<<" and skip until the end.
8471e57026

src/nvim/eval.c

@@ -21269,6 +21269,7 @@ void ex_function(exarg_T *eap)
   int indent;
   int nesting;
   char_u      *skip_until = NULL;
+  char_u *trimmed = NULL;
   dictitem_T  *v;
   funcdict_T fudi;
   static int func_nr = 0;           /* number for nameless function */
@@ -21572,10 +21573,14 @@ void ex_function(exarg_T *eap)
       sourcing_lnum_off = 0;
 
     if (skip_until != NULL) {
-      /* between ":append" and "." and between ":python <<EOF" and "EOF"
-       * don't check for ":endfunc". */
-      if (STRCMP(theline, skip_until) == 0) {
-        XFREE_CLEAR(skip_until);
+      // Between ":append" and "." and between ":python <<EOF" and "EOF"
+      // don't check for ":endfunc".
+      if (trimmed == NULL || STRNCMP(theline, trimmed, STRLEN(trimmed)) == 0) {
+        p = trimmed == NULL ? theline : theline + STRLEN(trimmed);
+        if (STRCMP(p, skip_until) == 0) {
+          XFREE_CLEAR(skip_until);
+          XFREE_CLEAR(trimmed);
+        }
       }
     } else {
       /* skip ':' and blanks*/
@@ -21674,6 +21679,27 @@ void ex_function(exarg_T *eap)
         else
           skip_until = vim_strsave(p);
       }
+
+      // Check for ":let v =<< [trim] EOF"
+      arg = skipwhite(skiptowhite(p));
+      arg = skipwhite(skiptowhite(arg));
+      if (arg[0] == '=' && arg[1] == '<' && arg[2] =='<'
+          && ((p[0] == 'l' && p[1] == 'e'
+               && (!ASCII_ISALNUM(p[2])
+                   || (p[2] == 't' && !ASCII_ISALNUM(p[3])))))) {
+        // ":let v =<<" continues until a dot
+        p = skipwhite(arg + 3);
+        if (STRNCMP(p, "trim", 4) == 0) {
+          // Ignore leading white space.
+          p = skipwhite(p + 4);
+          trimmed = vim_strnsave(theline, (int)(skipwhite(theline) - theline));
+        }
+        if (*p == NUL) {
+          skip_until = vim_strsave((char_u *)".");
+        } else {
+          skip_until = vim_strnsave(p, (int)(skiptowhite(p) - p));
+        }
+      }
     }
 
     /* Add the line to the function. */

src/nvim/testdir/test_let.vim

@@ -141,6 +141,27 @@ func Test_let_varg_fail()
   call s:set_varg8([0])
 endfunction
 
+func Test_let_heredoc_fails()
+  call assert_fails('let v =<< marker', 'E991:')
+
+  let text =<< trim END
+  func WrongSyntax()
+    let v =<< that there
+  endfunc
+  END
+  call writefile(text, 'XheredocFail')
+  call assert_fails('source XheredocFail', 'E126:')
+  call delete('XheredocFail')
+
+  let text =<< trim END
+  func MissingEnd()
+    let v =<< END
+  endfunc
+  END
+  call writefile(text, 'XheredocWrong')
+  call assert_fails('source XheredocWrong', 'E126:')
+  call delete('XheredocWrong')
+endfunc
 
 " Test for the setting a variable using the heredoc syntax
 func Test_let_heredoc()
@@ -170,12 +191,12 @@ END
 END
   call assert_equal(['vim', '', 'end', '  END', 'END '], var3)
 
-        let var1 =<< trim END
-        Line1
-          Line2
-        	Line3
-         END
-        END
+  let var1 =<< trim END
+  Line1
+    Line2
+  	Line3
+   END
+  END
   call assert_equal(['Line1', '  Line2', "\tLine3", ' END'], var1)
 
   let var1 =<< trim
@@ -183,15 +204,45 @@ END
   .
   call assert_equal(['  Line1'], var1)
 
-  call assert_fails('let v =<< marker', 'E991:')
-  call assert_fails('call WrongSyntax()', 'E488:')
-  call assert_fails('call MissingEnd()', 'E990:')
+  " ignore "endfunc"
+  let var1 =<< END
+something
 endfunc
+END
+  call assert_equal(['something', 'endfunc'], var1)
 
-func WrongSyntax()
-  let fail =<< that there
-endfunc
+  " ignore "endfunc" with trim
+  let var1 =<< trim END
+  something
+  endfunc
+  END
+  call assert_equal(['something', 'endfunc'], var1)
 
-func MissingEnd()
-  let fail =<< END
+  " ignore "python << xx"
+  let var1 =<<END
+something
+python << xx
+END
+  call assert_equal(['something', 'python << xx'], var1)
+
+  " ignore "python << xx" with trim
+  let var1 =<< trim END
+  something
+  python << xx
+  END
+  call assert_equal(['something', 'python << xx'], var1)
+
+  " ignore "append"
+  let var1 =<<
+something
+app
+.
+  call assert_equal(['something', 'app'], var1)
+
+  " ignore "append" with trim
+  let var1 =<< trim
+  something
+  app
+  .
+  call assert_equal(['something', 'app'], var1)
 endfunc