Fix warnings on newer versions of gcc;

src/api/l_canvas.c

@@ -55,7 +55,7 @@ static int l_lovrCanvasNewTextureData(lua_State* L) {
   uint32_t index = luaL_optinteger(L, 2, 1) - 1;
   uint32_t count;
   lovrCanvasGetAttachments(canvas, &count);
-  lovrAssert(index >= 0 && index < count, "Can not create a TextureData from Texture #%d of Canvas (it only has %d textures)", index, count);
+  lovrAssert(index < count, "Can not create a TextureData from Texture #%d of Canvas (it only has %d textures)", index, count);
   TextureData* textureData = lovrCanvasNewTextureData(canvas, index);
   luax_pushtype(L, TextureData, textureData);
   lovrRelease(TextureData, textureData);

src/api/l_graphics.c

@@ -1538,11 +1538,11 @@ static int l_lovrGraphicsNewTexture(lua_State* L) {
     lua_pop(L, 1);
 
     lua_getfield(L, index, "type");
-    type = lua_isnil(L, -1) ? type : luaL_checkoption(L, -1, NULL, TextureTypes);
+    type = lua_isnil(L, -1) ? type : (TextureType) luaL_checkoption(L, -1, NULL, TextureTypes);
     lua_pop(L, 1);
 
     lua_getfield(L, index, "format");
-    format = lua_isnil(L, -1) ? format : luaL_checkoption(L, -1, NULL, TextureFormats);
+    format = lua_isnil(L, -1) ? format : (TextureFormat) luaL_checkoption(L, -1, NULL, TextureFormats);
     lua_pop(L, 1);
 
     lua_getfield(L, index, "msaa");

src/api/l_mesh.c

@@ -174,7 +174,7 @@ static int l_lovrMeshGetVertex(lua_State* L) {
 static int l_lovrMeshSetVertex(lua_State* L) {
   Mesh* mesh = luax_checktype(L, 1, Mesh);
   uint32_t index = luaL_checkinteger(L, 2) - 1;
-  lovrAssert(index >= 0 && index < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex index: %d", index + 1);
+  lovrAssert(index < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex index: %d", index + 1);
   bool table = lua_istable(L, 3);
 
   if (!mesh->vertexBuffer || mesh->attributeCount == 0 || mesh->attributes[0].buffer != mesh->vertexBuffer) {
@@ -222,7 +222,7 @@ static int l_lovrMeshGetVertexAttribute(lua_State* L) {
   uint32_t attributeIndex = luaL_checkinteger(L, 3) - 1;
   Buffer* buffer = lovrMeshGetVertexBuffer(mesh);
   lovrAssert(lovrBufferIsReadable(buffer), "Mesh:getVertex can only be used if the Mesh was created with the readable flag");
-  lovrAssert(vertexIndex >= 0 && vertexIndex < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex: %d", vertexIndex + 1);
+  lovrAssert(vertexIndex < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex: %d", vertexIndex + 1);
   lovrAssert(attributeIndex < mesh->attributeCount, "Invalid mesh attribute: %d", attributeIndex + 1);
   lovrAssert(mesh->attributes[attributeIndex].buffer == mesh->vertexBuffer, "Invalid mesh attribute: %d", attributeIndex + 1);
   MeshAttribute* attribute = &mesh->attributes[attributeIndex];
@@ -246,7 +246,7 @@ static int l_lovrMeshSetVertexAttribute(lua_State* L) {
   uint32_t vertexIndex = luaL_checkinteger(L, 2) - 1;
   uint32_t attributeIndex = luaL_checkinteger(L, 3) - 1;
   bool table = lua_istable(L, 4);
-  lovrAssert(vertexIndex >= 0 && vertexIndex < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex: %d", vertexIndex + 1);
+  lovrAssert(vertexIndex < lovrMeshGetVertexCount(mesh), "Invalid mesh vertex: %d", vertexIndex + 1);
   lovrAssert(attributeIndex < mesh->attributeCount, "Invalid mesh attribute: %d", attributeIndex + 1);
   lovrAssert(mesh->attributes[attributeIndex].buffer == mesh->vertexBuffer, "Invalid mesh attribute: %d", attributeIndex + 1);
   MeshAttribute* attribute = &mesh->attributes[attributeIndex];

src/core/ref.h

@@ -28,6 +28,6 @@ static inline uint32_t ref_dec(Ref* ref) { return --*ref; }
 void* _lovrAlloc(size_t size);
 #define toRef(o) (Ref*) (o) - 1
 #define lovrAlloc(T) (T*) _lovrAlloc(sizeof(T))
-#define lovrRetain(o) o && !ref_inc(toRef(o))
+#define lovrRetain(o) if (o && !ref_inc(toRef(o))) { lovrThrow("Refcount overflow in %s:%d", __FILE__, __LINE__); }
 #define lovrRelease(T, o) if (o && !ref_dec(toRef(o))) lovr ## T ## Destroy(o), free(toRef(o));
 #define _lovrRelease(o, f) if (o && !ref_dec(toRef(o))) f(o), free(toRef(o));

src/lib/vec/vec.h

@@ -33,7 +33,7 @@
 
 #define vec_push(v, val)\
   ( vec_expand_(vec_unpack_(v)) ? -1 :\
-    ((v)->data[(v)->length++] = (val), 0), 0 )
+    ((v)->data[(v)->length++] = (val), 0) )
 
 
 #define vec_pop(v)\