patch 9.1.0335: String interpolation fails for List type

Problem:  String interpolation fails for List type
Solution: use implicit string(list) for string interpolation and :put =
          (Yegappan Lakshmanan)

related: #14529
closes: #14556

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_expr.vim b/src/testdir/test_expr.vim
index 1fa460d..6acfe00 100644
--- a/src/testdir/test_expr.vim
+++ b/src/testdir/test_expr.vim
@@ -953,6 +953,18 @@
     #" Dict interpolation
     VAR d = {'a': 10, 'b': [1, 2]}
     call assert_equal("{'a': 10, 'b': [1, 2]}", $'{d}')
+    VAR emptydict = {}
+    call assert_equal("a{}b", $'a{emptydict}b')
+    VAR nulldict = test_null_dict()
+    call assert_equal("a{}b", $'a{nulldict}b')
+
+    #" List interpolation
+    VAR l = ['a', 'b', 'c']
+    call assert_equal("['a', 'b', 'c']", $'{l}')
+    VAR emptylist = []
+    call assert_equal("a[]b", $'a{emptylist}b')
+    VAR nulllist = test_null_list()
+    call assert_equal("a[]b", $'a{nulllist}b')
 
     #" Stray closing brace.
     call assert_fails('echo $"moo}"', 'E1278:')
diff --git a/src/testdir/test_let.vim b/src/testdir/test_let.vim
index fec0273..2aba1d3 100644
--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -696,6 +696,41 @@
   END
   call assert_equal(["let d2 = {'a': 10, 'b': 'ss', 'c': {}}"], code)
 
+  " Empty dictionary
+  let d1 = {}
+  let code =<< eval trim END
+    let d2 = {d1}
+  END
+  call assert_equal(["let d2 = {}"], code)
+
+  " null dictionary
+  let d1 = test_null_dict()
+  let code =<< eval trim END
+    let d2 = {d1}
+  END
+  call assert_equal(["let d2 = {}"], code)
+
+  " Evaluate a List
+  let l1 = ['a', 'b', 'c']
+  let code =<< eval trim END
+    let l2 = {l1}
+  END
+  call assert_equal(["let l2 = ['a', 'b', 'c']"], code)
+
+  " Empty List
+  let l1 = []
+  let code =<< eval trim END
+    let l2 = {l1}
+  END
+  call assert_equal(["let l2 = []"], code)
+
+  " Null List
+  let l1 = test_null_list()
+  let code =<< eval trim END
+    let l2 = {l1}
+  END
+  call assert_equal(["let l2 = []"], code)
+
   let code = 'xxx'
   let code =<< eval trim END
     let n = {5 +
diff --git a/src/testdir/test_put.vim b/src/testdir/test_put.vim
index 6f1e992..69c2943 100644
--- a/src/testdir/test_put.vim
+++ b/src/testdir/test_put.vim
Binary files differ
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 4da368c..4296c37 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -2994,6 +2994,56 @@
   CODE
   v9.CheckDefAndScriptSuccess(lines)
 
+  # Evaluate an empty dictionary
+  lines =<< trim CODE
+    var d1 = {}
+    var code =<< trim eval END
+      var d2 = {d1}
+    END
+    assert_equal(["var d2 = {}"], code)
+  CODE
+  v9.CheckDefAndScriptSuccess(lines)
+
+  # Evaluate a null dictionary
+  lines =<< trim CODE
+    var d1 = test_null_dict()
+    var code =<< trim eval END
+      var d2 = {d1}
+    END
+    assert_equal(["var d2 = {}"], code)
+  CODE
+  v9.CheckDefAndScriptSuccess(lines)
+
+  # Evaluate a List
+  lines =<< trim CODE
+    var l1 = ['a', 'b', 'c']
+    var code =<< trim eval END
+      var l2 = {l1}
+    END
+    assert_equal(["var l2 = ['a', 'b', 'c']"], code)
+  CODE
+  v9.CheckDefAndScriptSuccess(lines)
+
+  # Evaluate an empty List
+  lines =<< trim CODE
+    var l1 = []
+    var code =<< trim eval END
+      var l2 = {l1}
+    END
+    assert_equal(["var l2 = []"], code)
+  CODE
+  v9.CheckDefAndScriptSuccess(lines)
+
+  # Evaluate a null List
+  lines =<< trim CODE
+    var l1 = test_null_list()
+    var code =<< trim eval END
+      var l2 = {l1}
+    END
+    assert_equal(["var l2 = []"], code)
+  CODE
+  v9.CheckDefAndScriptSuccess(lines)
+
   lines =<< trim CODE
     var code =<< eval trim END
       var s = "{$SOME_ENV_VAR}"