pg_locale_libc.c: add missing casts to unsigned char.

Discussion: https://postgr.es/m/20260630012919.78@rfd.leadboat.com
Backpatch-through: 19

diff --git a/src/backend/utils/adt/pg_locale_libc.c b/src/backend/utils/adt/pg_locale_libc.c
index 0043371586dc73af525ede7520ae21150565949f..b50b3f24efdb72068f3dfd73f5399a27114b87de 100644 (file)
--- a/src/backend/utils/adt/pg_locale_libc.c
+++ b/src/backend/utils/adt/pg_locale_libc.c
@@ -527,7 +527,7 @@ strlower_libc_sb(char *dest, size_t destsize, const char *src, size_t srclen,
                        {
                                if (*p >= 'A' && *p <= 'Z')
                                        *p += 'a' - 'A';
-                               else if (IS_HIGHBIT_SET(*p) && isupper_l(*p, loc))
+                               else if (IS_HIGHBIT_SET(*p) && isupper_l((unsigned char) *p, loc))
                                        *p = tolower_l((unsigned char) *p, loc);
                        }
                        else
@@ -611,14 +611,14 @@ strtitle_libc_sb(char *dest, size_t destsize, const char *src, size_t srclen,
                                {
                                        if (*p >= 'A' && *p <= 'Z')
                                                *p += 'a' - 'A';
-                                       else if (IS_HIGHBIT_SET(*p) && isupper_l(*p, loc))
+                                       else if (IS_HIGHBIT_SET(*p) && isupper_l((unsigned char) *p, loc))
                                                *p = tolower_l((unsigned char) *p, loc);
                                }
                                else
                                {
                                        if (*p >= 'a' && *p <= 'z')
                                                *p -= 'a' - 'A';
-                                       else if (IS_HIGHBIT_SET(*p) && islower_l(*p, loc))
+                                       else if (IS_HIGHBIT_SET(*p) && islower_l((unsigned char) *p, loc))
                                                *p = toupper_l((unsigned char) *p, loc);
                                }
                        }
@@ -713,7 +713,7 @@ strupper_libc_sb(char *dest, size_t destsize, const char *src, size_t srclen,
                        {
                                if (*p >= 'a' && *p <= 'z')
                                        *p -= 'a' - 'A';
-                               else if (IS_HIGHBIT_SET(*p) && islower_l(*p, loc))
+                               else if (IS_HIGHBIT_SET(*p) && islower_l((unsigned char) *p, loc))
                                        *p = toupper_l((unsigned char) *p, loc);
                        }
                        else