feat(decoration): allow conceal_char to be a composing char

decor->text.str pointer must go. This removes it for conceal char,
in preparation for a larger PR which will also handle the sign case.

By actually allowing composing chars for a conceal chars, this
becomes a feature and not just a refactor, as a bonus.

2 files changed, 7 insertions, 0 deletions

diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index 57491b34d6..ba3b7c0915 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -645,6 +645,10 @@ nvim__inspect_cell({grid}, {row}, {col})                *nvim__inspect_cell()*
     NB: if your UI doesn't use hlstate, this will not return hlstate first
     time.
 
+nvim__invalidate_glyph_cache()                *nvim__invalidate_glyph_cache()*
+    For testing. The condition in schar_cache_clear_if_full is hard to reach,
+    so this function can be used to force a cache clear in a test.
+
 nvim__stats()                                                  *nvim__stats()*
     Gets internal stats.
 
diff --git a/runtime/lua/vim/_meta/api.lua b/runtime/lua/vim/_meta/api.lua
index 006996ad4e..b5975e0d42 100644
--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@@ -80,6 +80,9 @@ function vim.api.nvim__id_float(flt) end
 function vim.api.nvim__inspect_cell(grid, row, col) end
 
 --- @private
+--- For testing. The condition in schar_cache_clear_if_full is hard to reach,
+--- so this function can be used to force a cache clear in a test.
+---
 function vim.api.nvim__invalidate_glyph_cache() end
 
 --- @private