vim-patch:8.2.2068: transparent syntax item uses start/end of containing region (#19055)

Problem:    Transparent syntax item uses start/end of containing region.
Solution:   Do not change the startpos and endpos of a transparent region to
            that of its containing region. (Adrian Ghizaru, closes vim/vim#7349,
            closes vim/vim#7391)
https://github.com/vim/vim/commit/b46f57e87b3706a8c4b97d8e03f7853a7938b061

2 files changed, 76 insertions, 2 deletions

diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 47305b6709..0d43458b5b 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -2381,8 +2381,6 @@ static void update_si_attr(int idx)
     } else {
       sip->si_attr = CUR_STATE(idx - 1).si_attr;
       sip->si_trans_id = CUR_STATE(idx - 1).si_trans_id;
-      sip->si_h_startpos = CUR_STATE(idx - 1).si_h_startpos;
-      sip->si_h_endpos = CUR_STATE(idx - 1).si_h_endpos;
       if (sip->si_cont_list == NULL) {
         sip->si_flags |= HL_TRANS_CONT;
         sip->si_cont_list = CUR_STATE(idx - 1).si_cont_list;
diff --git a/src/nvim/testdir/test_syntax.vim b/src/nvim/testdir/test_syntax.vim
index 6bef61ae8f..c46bba04e3 100644
--- a/src/nvim/testdir/test_syntax.vim
+++ b/src/nvim/testdir/test_syntax.vim
@@ -778,6 +778,82 @@ func Test_search_syntax_skip()
   bwipe!
 endfunc
 
+func Test_syn_contained_transparent()
+  " Comments starting with "Regression:" show the result when the highlighting
+  " span of the containing item is assigned to the contained region.
+  syntax on
+
+  let l:case = "Transparent region contained in region"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax region Y start=/(/ end=/)/ contains=X
+
+  call setline(1,  "==(--[~~]--)==")
+  let l:expected = "  YYYYYYYYYY  "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+
+  let l:case = "Transparent region extends region"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax region Y start=/(/ end=/)/ end=/e/ contains=X
+
+  call setline(1,  "==(--[~~e~~]--)==")
+  let l:expected = "  YYYYYYYYYYYYY  "
+  " Regression:    "  YYYYYYY   YYY  "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+
+  let l:case = "Nested transparent regions extend region"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax region Y start=/(/ end=/)/ end=/e/ contains=X
+
+  call setline(1,  "==(--[~~e~~[~~e~~]~~e~~]--)==")
+  let l:expected = "  YYYYYYYYYYYYYYYYYYYYYYYYY  "
+  " Regression:    "  YYYYYYY         YYYYYYYYY  "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+
+  let l:case = "Transparent region contained in match"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax match Y /(.\{-})/ contains=X
+
+  call setline(1,  "==(--[~~]--)==")
+  let l:expected = "  YYYYYYYYYY  "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+
+  let l:case = "Transparent region extends match"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax match Y /(.\{-}[e)]/ contains=X
+
+  call setline(1,  "==(--[~~e~~]--)==")
+  let l:expected = "  YYYYYYYYYY     "
+  " Regression:    "  YYYYYYY        "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+
+  let l:case = "Nested transparent regions extend match"
+  new
+  syntax region X start=/\[/ end=/\]/ contained transparent
+  syntax match Y /(.\{-}[e)]/ contains=X
+
+  call setline(1,  "==(--[~~e~~[~~e~~]~~e~~]--)==")
+  let l:expected = "  YYYYYYYYYYYYYYYYYYYYYY     "
+  " Regression:    "  YYYYYYY         YYYYYY     "
+  eval AssertHighlightGroups(1, 1, l:expected, 1, l:case)
+  syntax clear Y X
+  bw!
+endfunc
+
 func Test_syn_include_contains_TOP()
   let l:case = "TOP in included syntax means its group list name"
   new