patch 8.1.1591: on error garbage collection may free memory in use
Problem: On error garbage collection may free memory in use.
Solution: Reset may_garbage_collect when evaluating expression mapping.
Add tests. (Ozaki Kiichi, closes #4579)
diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index a361b2f..7f90b03 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -397,3 +397,39 @@
delfunc Select
delfunc GetCommand
endfunc
+
+func Test_error_in_map_expr()
+ if !has('terminal') || (has('win32') && has('gui_running'))
+ throw 'Skipped: cannot run Vim in a terminal window'
+ endif
+
+ let lines =<< trim [CODE]
+ func Func()
+ " fail to create list
+ let x = [
+ endfunc
+ nmap <expr> ! Func()
+ set updatetime=50
+ [CODE]
+ call writefile(lines, 'Xtest.vim')
+
+ let buf = term_start(GetVimCommandClean() .. ' -S Xtest.vim', {'term_rows': 8})
+ let job = term_getjob(buf)
+ call WaitForAssert({-> assert_notequal('', term_getline(buf, 8))})
+
+ " GC must not run during map-expr processing, which can make Vim crash.
+ call term_sendkeys(buf, '!')
+ call term_wait(buf, 100)
+ call term_sendkeys(buf, "\<CR>")
+ call term_wait(buf, 100)
+ call assert_equal('run', job_status(job))
+
+ call term_sendkeys(buf, ":qall!\<CR>")
+ call WaitFor({-> job_status(job) ==# 'dead'})
+ if has('unix')
+ call assert_equal('', job_info(job).termsig)
+ endif
+
+ call delete('Xtest.vim')
+ exe buf .. 'bwipe!'
+endfunc