Commit: patch 9.2.0767: legacy/vim9cmd modifiers do not set script version for options values

[Christian Brabandt]

patch 9.2.0767: legacy/vim9cmd modifiers do not set script version for options values

Commit: https://github.com/vim/vim/commit/02f2745e2757f8353e2e76db130682ed966f5544
Author: Illia Bobyr <illia...@gmail.com>
Date: Thu Jul 2 18:40:03 2026 +0000

patch 9.2.0767: legacy/vim9cmd modifiers do not set script version for options values

Problem: legacy/vim9cmd modifiers do not set script version for options
values
Solution: Set the correct script version depending on command modifier
flags (Illia Bobyr)

When remembering script context for an option value we should consider
flags "CMOD_LEGACY" and "CMOD_VIM9CMD" set in "cmdmod.cmd_flags" by the
":legacy" and ":vim9cmd" command prefixes. Otherwise, if an option
value is an expression, it might be evaluated in an incorrect context.

closes: #20683

Signed-off-by: Illia Bobyr <illia...@gmail.com>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/src/option.c b/src/option.c
index 9d291d180..9a869fdb9 100644
--- a/src/option.c
+++ b/src/option.c
@@ -3498,6 +3498,14 @@ set_option_sctx_idx(int opt_idx, int opt_flags, sctx_T script_ctx)
if (!(opt_flags & OPT_MODELINE))
new_script_ctx.sc_lnum += SOURCING_LNUM;

+ // ":legacy" and ":vim9cmd" change the execution context of an option.
+ if (cmdmod.cmod_flags & CMOD_VIM9CMD)
+ new_script_ctx.sc_version = SCRIPT_VERSION_VIM9;
+ if (cmdmod.cmod_flags & CMOD_LEGACY)
+ // It is a bit confusing, but "MAX" is actually the legacy Vim script
+ // version before Vim9.
+ new_script_ctx.sc_version = SCRIPT_VERSION_MAX;
+
// Remember where the option was set. For local options need to do that
// in the buffer or window structure.
if (both || (opt_flags & OPT_GLOBAL) || (indir & (PV_BUF|PV_WIN)) == 0)
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index cec81f3ed..1f421e2a4 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -97,6 +97,43 @@ def Test_vim9cmd()
v9.CheckScriptFailure(lines, 'E1017:')
enddef

+def Test_legacy_vim9cmd_preserved_by_options()
+ # Make sure that "legacy" and "vim9cmd" prefix affects value of an option that
+ # is a script expression.
+
+ var lines: list<string>
+
+ lines =<< trim END
+ vim9script
+ try
+ legacy set indentexpr='a'.'b'=='ab'
+ set debug=throw
+ normal O
+ finally
+ set debug& indentexpr&
+ endtry
+ END
+ # "'a'.'b'=='ab'" evaluated as a Vim9 expression produces:
+ #
+ # > E1030: Using a String as a Number: "a"
+ v9.CheckScriptSuccess(lines)
+
+ lines =<< trim END
+ try
+ vim9cmd set indentexpr=type((x)\ =>\ x)\ ==\ v:t_func\ ?\ 1\ :\ 0
+ set debug=throw
+ normal O
+ finally
+ set debug& indentexpr&
+ endtry
+ END
+ # "type((x) => x) == v:t_func ? 1 : 0" evaluated as a legacy expression
+ # produces:
+ #
+ # > E121: Undefined variable: x
+ v9.CheckScriptSuccess(lines)
+enddef
+
def Test_defcompile_fails()
assert_fails('defcompile NotExists', 'E1061:')
assert_fails('defcompile debug debug Test_defcompile_fails', 'E488:')
diff --git a/src/version.c b/src/version.c
index 2c531eb5b..da6de9304 100644
--- a/src/version.c
+++ b/src/version.c
@@ -759,6 +759,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 767,
/**/
766,
/**/