From 0672595fd50e9ae668676a40e28ebf66d7f52392 Mon Sep 17 00:00:00 2001
From: Yegappan Lakshmanan <yegappan@yahoo.com>
Date: Wed, 18 Oct 2023 11:47:37 +0200
Subject: patch 9.0.2044: Vim9: exceptions confuse defered functions

Problem:  Vim9: exceptions confuse defered functions
Solution: save and restore exception state when calling defered
          functions

closes: #13364
closes: #13372

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>
---
 src/testdir/test_user_func.vim   | 26 ++++++++++++++++++++++++++
 src/testdir/test_vim9_script.vim | 29 +++++++++++++++++++++++++++++
 src/userfunc.c                   | 15 +++++++++++++++
 src/version.c                    |  2 ++
 src/vim9execute.c                | 15 +++++++++++++++
 5 files changed, 87 insertions(+)

(limited to 'src')

diff --git a/src/testdir/test_user_func.vim b/src/testdir/test_user_func.vim
index 82b5f91c6b..8fc82c4e38 100644
--- a/src/testdir/test_user_func.vim
+++ b/src/testdir/test_user_func.vim
@@ -870,5 +870,31 @@ func Test_defer_wrong_arguments()
   call v9.CheckScriptFailure(lines, 'E1013: Argument 1: type mismatch, expected string but got number')
 endfunc
 
+" Test for calling a deferred function after an exception
+func Test_defer_after_exception()
+  let g:callTrace = []
+  func Defer()
+    let g:callTrace += ['a']
+    let g:callTrace += ['b']
+    let g:callTrace += ['c']
+    let g:callTrace += ['d']
+  endfunc
+
+  func Foo()
+    defer Defer()
+    throw "TestException"
+  endfunc
+
+  try
+    call Foo()
+  catch /TestException/
+    let g:callTrace += ['e']
+  endtry
+  call assert_equal(['a', 'b', 'c', 'd', 'e'], g:callTrace)
+
+  delfunc Defer
+  delfunc Foo
+  unlet g:callTrace
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index a16c5ae198..f8280c6d28 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -4686,6 +4686,35 @@ def Test_refer_funcref_instr_after_realloc()
   v9.CheckScriptSuccess(lines)
 enddef
 
+" Test for calling a deferred function after an exception
+def Test_defer_after_exception()
+  var lines =<< trim END
+    vim9script
+
+    var callTrace: list<string> = []
+    def Defer()
+      callTrace += ['a']
+      callTrace += ['b']
+      callTrace += ['c']
+      callTrace += ['d']
+    enddef
+
+    def Foo()
+      defer Defer()
+      throw "TestException"
+    enddef
+
+    try
+      Foo()
+    catch /TestException/
+      callTrace += ['e']
+    endtry
+
+    assert_equal(['a', 'b', 'c', 'd', 'e'], callTrace)
+  END
+  v9.CheckScriptSuccess(lines)
+enddef
+
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
   new
diff --git a/src/userfunc.c b/src/userfunc.c
index a3b8bdc103..092b3927b5 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -6251,8 +6251,23 @@ handle_defer_one(funccall_T *funccal)
 	char_u *name = dr->dr_name;
 	dr->dr_name = NULL;
 
+	// If the deferred function is called after an exception, then only the
+	// first statement in the function will be executed.  Save and restore
+	// the try/catch/throw exception state.
+	int save_trylevel = trylevel;
+	int save_did_throw = did_throw;
+	int save_need_rethrow = need_rethrow;
+
+	trylevel = 0;
+	did_throw = FALSE;
+	need_rethrow = FALSE;
+
 	call_func(name, -1, &rettv, dr->dr_argcount, dr->dr_argvars, &funcexe);
 
+	trylevel = save_trylevel;
+	did_throw = save_did_throw;
+	need_rethrow = save_need_rethrow;
+
 	clear_tv(&rettv);
 	vim_free(name);
 	for (int i = dr->dr_argcount - 1; i >= 0; --i)
diff --git a/src/version.c b/src/version.c
index bad07e6446..6a820828bf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2044,
 /**/
     2043,
 /**/
diff --git a/src/vim9execute.c b/src/vim9execute.c
index 1fdff84da7..dd3d263b52 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -1140,8 +1140,23 @@ invoke_defer_funcs(ectx_T *ectx)
 	char_u *name = functv->vval.v_string;
 	functv->vval.v_string = NULL;
 
+	// If the deferred function is called after an exception, then only the
+	// first statement in the function will be executed.  Save and restore
+	// the try/catch/throw exception state.
+	int save_trylevel = trylevel;
+	int save_did_throw = did_throw;
+	int save_need_rethrow = need_rethrow;
+
+	trylevel = 0;
+	did_throw = FALSE;
+	need_rethrow = FALSE;
+
 	(void)call_func(name, -1, &rettv, argcount, argvars, &funcexe);
 
+	trylevel = save_trylevel;
+	did_throw = save_did_throw;
+	need_rethrow = save_need_rethrow;
+
 	clear_tv(&rettv);
 	vim_free(name);
     }
-- 
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