ci: enable CI_BUILD on windows (#21557)

This will ensure warnings are treated as errors when using MSVC.

Also fix const correctness warnings. The warnings in mbyte.c are false
positives that triggers this warning on MSVC v19.32 and lower, which our
CI still use. The (void *) casts can be removed once the CI MSVC version
has been upgraded to v19.33 or higher.

4 files changed, 16 insertions, 13 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 399ac24ecc..b158d966e1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -304,7 +304,7 @@ jobs:
 
       - name: Build nvim
         run: |
-          cmake -B build -G Ninja -DCMAKE_BUILD_TYPE='RelWithDebInfo' -DDEPS_PREFIX="$env:DEPS_PREFIX"
+          cmake -B build -G Ninja -DCMAKE_BUILD_TYPE='RelWithDebInfo' -DDEPS_PREFIX="$env:DEPS_PREFIX" -DCI_BUILD=ON
           cmake --build build
 
       - name: Install test deps
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 316f12e302..6356335847 100755
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -455,8 +455,11 @@ endforeach()
 
 list(REMOVE_ITEM NVIM_SOURCES ${to_remove})
 
-if(NOT MSVC)
-  # xdiff, mpack, lua-cjson: inlined external project, we don't maintain it. #9306
+# xdiff, mpack, lua-cjson: inlined external project, we don't maintain it. #9306
+if(MSVC)
+  set_source_files_properties(
+    ${EXTERNAL_SOURCES} PROPERTIES COMPILE_FLAGS "${COMPILE_FLAGS} /wd4090")
+else()
   set_source_files_properties(
     ${EXTERNAL_SOURCES} PROPERTIES COMPILE_FLAGS "${COMPILE_FLAGS} -Wno-conversion -Wno-missing-noreturn -Wno-missing-format-attribute -Wno-double-promotion -Wno-strict-prototypes")
 endif()
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index eafbf0b17a..63f3b02feb 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -2709,7 +2709,7 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
     if (li_tv->v_type != VAR_LIST || li_tv->vval.v_list == NULL) {
       semsg(_(e_list_item_nr_is_not_list), item);
-      xfree(ptrs);
+      xfree((void *)ptrs);
       return;
     }
 
@@ -2727,23 +2727,23 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
         n1 = lili_tv->vval.v_number;
         if (n1 < 0x100) {
           emsg(_(e_only_values_of_0x100_and_higher_supported));
-          xfree(ptrs);
+          xfree((void *)ptrs);
           return;
         }
       } else if (i == 1 && lili_tv->vval.v_number < n1) {
         semsg(_(e_list_item_nr_range_invalid), item);
-        xfree(ptrs);
+        xfree((void *)ptrs);
         return;
       } else if (i == 2 && (lili_tv->vval.v_number < 1 || lili_tv->vval.v_number > 2)) {
         semsg(_(e_list_item_nr_cell_width_invalid), item);
-        xfree(ptrs);
+        xfree((void *)ptrs);
         return;
       }
     }
 
     if (i != 3) {
       semsg(_(e_list_item_nr_does_not_contain_3_numbers), item);
-      xfree(ptrs);
+      xfree((void *)ptrs);
       return;
     }
 
@@ -2762,7 +2762,7 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     const varnumber_T n1 = TV_LIST_ITEM_TV(lili)->vval.v_number;
     if (item > 0 && n1 <= table[item - 1].last) {
       semsg(_(e_overlapping_ranges_for_nr), (long)n1);
-      xfree(ptrs);
+      xfree((void *)ptrs);
       xfree(table);
       return;
     }
@@ -2773,7 +2773,7 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     table[item].width = (char)TV_LIST_ITEM_TV(lili)->vval.v_number;
   }
 
-  xfree(ptrs);
+  xfree((void *)ptrs);
 
   cw_interval_T *const cw_table_save = cw_table;
   const size_t cw_table_size_save = cw_table_size;
diff --git a/src/nvim/message.c b/src/nvim/message.c
index de4acd601f..7f29b19031 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -3006,7 +3006,7 @@ static int do_more_prompt(int typed_char)
 
 #if defined(MSWIN)
 /// Headless (no UI) error message handler.
-static void do_msg(char *str, bool errmsg)
+static void do_msg(const char *str, bool errmsg)
 {
   static bool did_err = false;
   assert(str != NULL);
@@ -3026,13 +3026,13 @@ static void do_msg(char *str, bool errmsg)
   }
 }
 
-void os_errmsg(char *str)
+void os_errmsg(const char *str)
 {
   do_msg(str, true);
 }
 
 /// Headless (no UI) message handler.
-void os_msg(char *str)
+void os_msg(const char *str)
 {
   do_msg(str, false);
 }