From 37ebf16a37c19d18b9927cfa3e38c31992994fe4 Mon Sep 17 00:00:00 2001
From: Patrick Gundlach <gundlach@speedata.de>
Date: Mon, 8 Dec 2025 21:04:12 +0100
Subject: [PATCH 1/2] Fix compiler warnings

See #69

Building with
CFLAGS="-std=gnu23 -Wall -Wextra -Wsign-compare" luarocks --local make
gives no compiler warnings
---
 src/luaharfbuzz/buffer.c | 2 +-
 src/luaharfbuzz/face.c   | 8 ++++----
 src/luaharfbuzz/font.c   | 8 ++++----
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/luaharfbuzz/buffer.c b/src/luaharfbuzz/buffer.c
index 5eb12eb..21e9bb2 100644
--- a/src/luaharfbuzz/buffer.c
+++ b/src/luaharfbuzz/buffer.c
@@ -143,7 +143,7 @@ static int buffer_add_codepoints(lua_State *L) {
   item_offset = luaL_optinteger(L, 3, 0);
   item_length = luaL_optinteger(L, 4, -1);
 
-  int n = lua_rawlen(L, 2);
+  unsigned int n = lua_rawlen(L, 2);
 
   hb_codepoint_t *text = (hb_codepoint_t *) malloc(n * sizeof(hb_codepoint_t));
 
diff --git a/src/luaharfbuzz/face.c b/src/luaharfbuzz/face.c
index d6c4fe8..655da04 100644
--- a/src/luaharfbuzz/face.c
+++ b/src/luaharfbuzz/face.c
@@ -492,7 +492,7 @@ static int face_var_get_axis_infos(lua_State *L) {
     hb_ot_var_get_axis_infos(*face, start, &count, axis_infos);
 
     lua_createtable(L, count, 0);
-    for (int i = 0; i != count; i++) {
+    for (unsigned int i = 0; i != count; i++) {
       push_axis_info(L, axis_infos + i);
       lua_seti(L, -2, i + 1);
     }
@@ -549,7 +549,7 @@ static int face_var_named_instance_get_design_coords(lua_State *L) {
   unsigned int count = STATIC_ARRAY_SIZE;
   count = hb_ot_var_named_instance_get_design_coords(*face, index, &count, coords);
 
-  for (int i = 0; i != count; i++) {
+  for (unsigned int i = 0; i != count; i++) {
     lua_pushnumber(L, coords[i]);
   }
   return count;
@@ -570,7 +570,7 @@ static int face_var_normalize_variations(lua_State *L) {
   int normalized[STATIC_ARRAY_SIZE];
   hb_ot_var_normalize_variations(*face, variations, count, normalized, coord_count);
 
-  for (int i = 0; i != coord_count; i++) {
+  for (unsigned int i = 0; i != coord_count; i++) {
     lua_pushinteger(L, normalized[i]);
   }
   return coord_count;
@@ -590,7 +590,7 @@ static int face_var_normalize_coords(lua_State *L) {
   int normalized[STATIC_ARRAY_SIZE];
   hb_ot_var_normalize_coords(*face, count, coords, normalized);
 
-  for (int i = 0; i != count; i++) {
+  for (unsigned int i = 0; i != count; i++) {
     lua_pushinteger(L, normalized[i]);
   }
   return count;
diff --git a/src/luaharfbuzz/font.c b/src/luaharfbuzz/font.c
index 4bb431d..f819cc4 100644
--- a/src/luaharfbuzz/font.c
+++ b/src/luaharfbuzz/font.c
@@ -249,7 +249,7 @@ static int font_set_variations(lua_State *L) {
   if (count > 128)
     count = 128;
   Variation variations[128];
-  for (int i = 0; i != count; i++)
+  for (unsigned int i = 0; i != count; i++)
     variations[i] = *(Variation *)luaL_checkudata(L, i + 2, "harfbuzz.Variation");
 
   hb_font_set_variations(*f, variations, count);
@@ -262,7 +262,7 @@ static int font_set_var_coords_design(lua_State *L) {
   if (count > 128)
     count = 128;
   float coords[128];
-  for (int i = 0; i != count; i++)
+  for (unsigned int i = 0; i != count; i++)
     coords[i] = luaL_checknumber(L, i + 2);
 
   hb_font_set_var_coords_design(*f, coords, count);
@@ -275,7 +275,7 @@ static int font_set_var_coords_normalized(lua_State *L) {
   if (count > 128)
     count = 128;
   int coords[128];
-  for (int i = 0; i != count; i++)
+  for (unsigned int i = 0; i != count; i++)
     coords[i] = luaL_checkinteger(L, i + 2);
 
   hb_font_set_var_coords_normalized(*f, coords, count);
@@ -294,7 +294,7 @@ static int font_get_var_coords_normalized(lua_State *L) {
   Font *f = (Font *)luaL_checkudata(L, 1, "harfbuzz.Font");
   unsigned int count;
   const int *coords = hb_font_get_var_coords_normalized(*f, &count);
-  for (int i = 0; i != count; i++)
+  for (unsigned int i = 0; i != count; i++)
     lua_pushinteger(L, coords[i]);
   return count;
 }

From 02a3e62d766f3f46216a15e45aaff6e1b7f4e44a Mon Sep 17 00:00:00 2001
From: Patrick Gundlach <gundlach@speedata.de>
Date: Mon, 8 Dec 2025 22:06:47 +0100
Subject: [PATCH 2/2] Add warning CFLAGS  to Makefile

---
 Makefile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 0984a8e..b4ff01c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,9 @@
 DOCS_DIR := docs
+# Default compiler flags (override with: make CFLAGS="...").
+CFLAGS ?= -Wall -Wextra -Wsign-compare -Werror
 
 build:
-	luarocks --local make
+	CFLAGS="$(CFLAGS)" luarocks --local make
 
 spec: test