vim-patch:9.0.1960: Make CI checks more strict

Problem:  Make CI checks more strict
Solution: Add -Wstrict-prototypes -Wmissing-prototypes to CI,
          fix uncovered problems

Add -Wstrict-prototypes -Wmissing-prototypes warnings check to CI

Add two new warnings to CI, silence some Perl related build-warnings:

- `strict-prototypes` helps prevent declaring a function with an empty
  argument list, e.g. `int func()`. In C++, that's equivalent to `int
  func(void)`, but in C, that means a function that can take any number
  of arguments which is rarely what we want.

- `missing-prototypes` makes sure we use `static` for file-only internal
  functions. Non-static functions should have been declared on a
  prototype file.

- Add `no-compound-token-split-by-macro` to the perl cflags, since it
  throws out a bunch of perl-related warnings that make the CI log
  unnecessary verbose and hard to read. This seems to happen only with
  clang 12 and above.

When applying those changes, it already uncovered a few warnings, so fix
up the code as well (fix prototypes, make the code static, remove
shadowed var declaration)

GTK header needs to have #pragma warning suppressiong because GTK2
headers will warn on `-Wstrict-prototypes`, and it's included by gui.h
and so we can't just turn off the warning in a couple files.

closes: vim/vim#13223
closes: vim/vim#13226

https://github.com/vim/vim/commit/f7f746b1672909ae57d2eec97253d6627f6c0887

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/src/nvim/optionstr.c b/src/nvim/optionstr.c
index f820a9fc49..3ea73560c1 100644
--- a/src/nvim/optionstr.c
+++ b/src/nvim/optionstr.c
@@ -676,8 +676,8 @@ static const char *did_set_option_listflag(char *val, char *flags, char *errbuf,
 }
 
 /// Expand an option that accepts a list of string values.
-int expand_set_opt_string(optexpand_T *args, char **values, size_t numValues, int *numMatches,
-                          char ***matches)
+static int expand_set_opt_string(optexpand_T *args, char **values, size_t numValues,
+                                 int *numMatches, char ***matches)
 {
   regmatch_T *regmatch = args->oe_regmatch;
   bool include_orig_val = args->oe_include_orig_val;
@@ -728,8 +728,8 @@ static char *expand_set_opt_callback(expand_T *xp, int idx)
 }
 
 /// Expand an option with a callback that iterates through a list of possible names.
-int expand_set_opt_generic(optexpand_T *args, CompleteListItemGetter func, int *numMatches,
-                           char ***matches)
+static int expand_set_opt_generic(optexpand_T *args, CompleteListItemGetter func, int *numMatches,
+                                  char ***matches)
 {
   set_opt_callback_orig_option = args->oe_include_orig_val ? args->oe_opt_value : NULL;
   set_opt_callback_func = func;
@@ -744,7 +744,7 @@ int expand_set_opt_generic(optexpand_T *args, CompleteListItemGetter func, int *
 }
 
 /// Expand an option which is a list of flags.
-int expand_set_opt_listflag(optexpand_T *args, char *flags, int *numMatches, char ***matches)
+static int expand_set_opt_listflag(optexpand_T *args, char *flags, int *numMatches, char ***matches)
 {
   char *option_val = args->oe_opt_value;
   char *cmdline_val = args->oe_set_arg;