py, unix: Allow to compile with -Wsign-compare.

See issue #699.

py/asmx86.c

@@ -398,7 +398,7 @@ void asm_x86_label_assign(asm_x86_t *as, mp_uint_t label) {
     assert(label < as->max_num_labels);
     if (as->pass < ASM_X86_PASS_EMIT) {
         // assign label offset
-        assert(as->label_offsets[label] == -1);
+        assert(as->label_offsets[label] == (mp_uint_t)-1);
         as->label_offsets[label] = as->code_offset;
     } else {
         // ensure label offset has not changed from PASS_COMPUTE to PASS_EMIT
@@ -407,7 +407,7 @@ void asm_x86_label_assign(asm_x86_t *as, mp_uint_t label) {
     }
 }
 
-STATIC mp_uint_t get_label_dest(asm_x86_t *as, int label) {
+STATIC mp_uint_t get_label_dest(asm_x86_t *as, mp_uint_t label) {
     assert(label < as->max_num_labels);
     return as->label_offsets[label];
 }
@@ -415,7 +415,7 @@ STATIC mp_uint_t get_label_dest(asm_x86_t *as, int label) {
 void asm_x86_jmp_label(asm_x86_t *as, mp_uint_t label) {
     mp_uint_t dest = get_label_dest(as, label);
     mp_int_t rel = dest - as->code_offset;
-    if (dest != -1 && rel < 0) {
+    if (dest != (mp_uint_t)-1 && rel < 0) {
         // is a backwards jump, so we know the size of the jump on the first pass
         // calculate rel assuming 8 bit relative jump
         rel -= 2;
@@ -437,7 +437,7 @@ void asm_x86_jmp_label(asm_x86_t *as, mp_uint_t label) {
 void asm_x86_jcc_label(asm_x86_t *as, mp_uint_t jcc_type, mp_uint_t label) {
     mp_uint_t dest = get_label_dest(as, label);
     mp_int_t rel = dest - as->code_offset;
-    if (dest != -1 && rel < 0) {
+    if (dest != (mp_uint_t)-1 && rel < 0) {
         // is a backwards jump, so we know the size of the jump on the first pass
         // calculate rel assuming 8 bit relative jump
         rel -= 2;

py/bc.c

@@ -116,7 +116,7 @@ void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t
         // Apply processing and check below only if we don't have kwargs,
         // otherwise, kw handling code below has own extensive checks.
         if (n_kw == 0 && !self->has_def_kw_args) {
-            if (n_args >= self->n_pos_args - self->n_def_args) {
+            if (n_args >= (mp_uint_t)(self->n_pos_args - self->n_def_args)) {
                 // given enough arguments, but may need to use some default arguments
                 for (mp_uint_t i = n_args; i < self->n_pos_args; i++) {
                     code_state->state[n_state - 1 - i] = self->extra_args[i - (self->n_pos_args - self->n_def_args)];

py/binary.c

@@ -256,7 +256,7 @@ void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte **
             }
     }
 
-    mp_binary_set_int(MIN(size, sizeof(val)), struct_type == '>', p, val);
+    mp_binary_set_int(MIN((size_t)size, sizeof(val)), struct_type == '>', p, val);
 }
 
 void mp_binary_set_val_array(char typecode, void *p, mp_uint_t index, mp_obj_t val_in) {

py/builtinimport.c

@@ -203,7 +203,7 @@ mp_obj_t mp_builtin___import__(mp_uint_t n_args, const mp_obj_t *args) {
             nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "Invalid relative import"));
         }
 
-        uint new_mod_l = (mod_len == 0 ? p - this_name : p - this_name + 1 + mod_len);
+        uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
         char *new_mod = alloca(new_mod_l);
         memcpy(new_mod, this_name, p - this_name);
         if (mod_len != 0) {

py/compile.c

@@ -216,12 +216,12 @@ STATIC mp_parse_node_t fold_constants(compiler_t *comp, mp_parse_node_t pn, mp_m
                     mp_int_t arg1 = MP_PARSE_NODE_LEAF_SMALL_INT(pns->nodes[2]);
                     if (MP_PARSE_NODE_IS_TOKEN_KIND(pns->nodes[1], MP_TOKEN_OP_DBL_LESS)) {
                         // int << int
-                        if (!(arg1 >= BITS_PER_WORD || arg0 > (MP_SMALL_INT_MAX >> arg1) || arg0 < (MP_SMALL_INT_MIN >> arg1))) {
+                        if (!(arg1 >= (mp_int_t)BITS_PER_WORD || arg0 > (MP_SMALL_INT_MAX >> arg1) || arg0 < (MP_SMALL_INT_MIN >> arg1))) {
                             pn = mp_parse_node_new_leaf(MP_PARSE_NODE_SMALL_INT, arg0 << arg1);
                         }
                     } else if (MP_PARSE_NODE_IS_TOKEN_KIND(pns->nodes[1], MP_TOKEN_OP_DBL_MORE)) {
                         // int >> int
-                        if (arg1 >= BITS_PER_WORD) {
+                        if (arg1 >= (mp_int_t)BITS_PER_WORD) {
                             // Shifting to big amounts is underfined behavior
                             // in C and is CPU-dependent; propagate sign bit.
                             arg1 = BITS_PER_WORD - 1;
@@ -386,8 +386,8 @@ STATIC scope_t *scope_new_and_link(compiler_t *comp, scope_kind_t kind, mp_parse
     return scope;
 }
 
-STATIC void apply_to_single_or_list(compiler_t *comp, mp_parse_node_t pn, int pn_list_kind, void (*f)(compiler_t*, mp_parse_node_t)) {
-    if (MP_PARSE_NODE_IS_STRUCT(pn) && MP_PARSE_NODE_STRUCT_KIND((mp_parse_node_struct_t*)pn) == pn_list_kind) {
+STATIC void apply_to_single_or_list(compiler_t *comp, mp_parse_node_t pn, pn_kind_t pn_list_kind, void (*f)(compiler_t*, mp_parse_node_t)) {
+    if (MP_PARSE_NODE_IS_STRUCT_KIND(pn, pn_list_kind)) {
         mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
         int num_nodes = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
         for (int i = 0; i < num_nodes; i++) {
@@ -398,7 +398,7 @@ STATIC void apply_to_single_or_list(compiler_t *comp, mp_parse_node_t pn, int pn
     }
 }
 
-STATIC int list_get(mp_parse_node_t *pn, int pn_kind, mp_parse_node_t **nodes) {
+STATIC int list_get(mp_parse_node_t *pn, pn_kind_t pn_kind, mp_parse_node_t **nodes) {
     if (MP_PARSE_NODE_IS_NULL(*pn)) {
         *nodes = NULL;
         return 0;
@@ -811,14 +811,14 @@ STATIC void c_assign_tuple(compiler_t *comp, mp_parse_node_t node_head, uint num
     uint num_head = (node_head == MP_PARSE_NODE_NULL) ? 0 : 1;
 
     // look for star expression
-    int have_star_index = -1;
+    uint have_star_index = -1;
     if (num_head != 0 && MP_PARSE_NODE_IS_STRUCT_KIND(node_head, PN_star_expr)) {
         EMIT_ARG(unpack_ex, 0, num_tail);
         have_star_index = 0;
     }
-    for (int i = 0; i < num_tail; i++) {
+    for (uint i = 0; i < num_tail; i++) {
         if (MP_PARSE_NODE_IS_STRUCT_KIND(nodes_tail[i], PN_star_expr)) {
-            if (have_star_index < 0) {
+            if (have_star_index == (uint)-1) {
                 EMIT_ARG(unpack_ex, num_head + i, num_tail - i - 1);
                 have_star_index = num_head + i;
             } else {
@@ -827,7 +827,7 @@ STATIC void c_assign_tuple(compiler_t *comp, mp_parse_node_t node_head, uint num
             }
         }
     }
-    if (have_star_index < 0) {
+    if (have_star_index == (uint)-1) {
         EMIT_ARG(unpack_sequence, num_head + num_tail);
     }
     if (num_head != 0) {
@@ -837,7 +837,7 @@ STATIC void c_assign_tuple(compiler_t *comp, mp_parse_node_t node_head, uint num
             c_assign(comp, node_head, ASSIGN_STORE);
         }
     }
-    for (int i = 0; i < num_tail; i++) {
+    for (uint i = 0; i < num_tail; i++) {
         if (num_head + i == have_star_index) {
             c_assign(comp, ((mp_parse_node_struct_t*)nodes_tail[i])->nodes[0], ASSIGN_STORE);
         } else {

py/emitbc.c

@@ -424,7 +424,7 @@ STATIC void emit_bc_label_assign(emit_t *emit, mp_uint_t l) {
     assert(l < emit->max_num_labels);
     if (emit->pass < MP_PASS_EMIT) {
         // assign label offset
-        assert(emit->label_offsets[l] == -1);
+        assert(emit->label_offsets[l] == (mp_uint_t)-1);
         emit->label_offsets[l] = emit->bytecode_offset;
     } else {
         // ensure label offset has not changed from MP_PASS_CODE_SIZE to MP_PASS_EMIT

py/lexer.c

@@ -657,7 +657,7 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
         // need to check for this special token in many places in the compiler.
         // TODO improve speed of these string comparisons
         //for (mp_int_t i = 0; tok_kw[i] != NULL; i++) {
-        for (mp_int_t i = 0; i < MP_ARRAY_SIZE(tok_kw); i++) {
+        for (size_t i = 0; i < MP_ARRAY_SIZE(tok_kw); i++) {
             if (str_strn_equal(tok_kw[i], lex->vstr.buf, lex->vstr.len)) {
                 if (i == MP_ARRAY_SIZE(tok_kw) - 1) {
                     // tok_kw[MP_ARRAY_SIZE(tok_kw) - 1] == "__debug__"

py/map.c

@@ -47,7 +47,7 @@ const mp_map_t mp_const_empty_map = {
 STATIC uint32_t doubling_primes[] = {0, 7, 19, 43, 89, 179, 347, 647, 1229, 2297, 4243, 7829, 14347, 26017, 47149, 84947, 152443, 273253, 488399, 869927, 1547173, 2745121, 4861607};
 
 STATIC mp_uint_t get_doubling_prime_greater_or_equal_to(mp_uint_t x) {
-    for (int i = 0; i < MP_ARRAY_SIZE(doubling_primes); i++) {
+    for (size_t i = 0; i < MP_ARRAY_SIZE(doubling_primes); i++) {
         if (doubling_primes[i] >= x) {
             return doubling_primes[i];
         }

py/mpz.c

@@ -1370,7 +1370,7 @@ mp_int_t mpz_hash(const mpz_t *z) {
 }
 
 bool mpz_as_int_checked(const mpz_t *i, mp_int_t *value) {
-    mp_int_t val = 0;
+    mp_uint_t val = 0;
     mpz_dig_t *d = i->dig + i->len;
 
     while (d-- > i->dig) {

py/obj.c

@@ -393,11 +393,11 @@ mp_uint_t mp_get_index(const mp_obj_type_t *type, mp_uint_t len, mp_obj_t index,
     if (is_slice) {
         if (i < 0) {
             i = 0;
-        } else if (i > len) {
+        } else if ((mp_uint_t)i > len) {
             i = len;
         }
     } else {
-        if (i < 0 || i >= len) {
+        if (i < 0 || (mp_uint_t)i >= len) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
                 nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "index out of range"));
             } else {

py/obj.h

@@ -86,7 +86,7 @@ typedef struct _mp_obj_base_t mp_obj_base_t;
 #define MP_OBJ_SMALL_INT_VALUE(o) (((mp_int_t)(o)) >> 1)
 #define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_int_t)(small_int)) << 1) | 1))
 
-#define MP_OBJ_QSTR_VALUE(o) (((mp_int_t)(o)) >> 2)
+#define MP_OBJ_QSTR_VALUE(o) (((mp_uint_t)(o)) >> 2)
 #define MP_OBJ_NEW_QSTR(qst) ((mp_obj_t)((((mp_uint_t)(qst)) << 2) | 2))
 
 // These macros are used to declare and define constant function objects
@@ -247,7 +247,7 @@ bool mp_get_buffer(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags);
 void mp_get_buffer_raise(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags);
 
 // Stream protocol
-#define MP_STREAM_ERROR (-1)
+#define MP_STREAM_ERROR ((mp_uint_t)-1)
 typedef struct _mp_stream_p_t {
     // On error, functions should return MP_STREAM_ERROR and fill in *errcode (values
     // are implementation-dependent, but will be exposed to user, e.g. via exception).

py/objint.c

@@ -334,7 +334,7 @@ STATIC mp_obj_t int_to_bytes(mp_uint_t n_args, const mp_obj_t *args) {
     // TODO: Support signed param (assumes signed=False)
 
     mp_int_t val = mp_obj_int_get_checked(args[0]);
-    mp_int_t len = MP_OBJ_SMALL_INT_VALUE(args[1]);
+    mp_uint_t len = MP_OBJ_SMALL_INT_VALUE(args[1]);
 
     byte *data;
     mp_obj_t o = mp_obj_str_builder_start(&mp_type_bytes, len, &data);

py/objlist.c

@@ -364,7 +364,7 @@ STATIC mp_obj_t list_insert(mp_obj_t self_in, mp_obj_t idx, mp_obj_t obj) {
     if (index < 0) {
          index = 0;
     }
-    if (index > self->len) {
+    if ((mp_uint_t)index > self->len) {
          index = self->len;
     }
 

py/objstr.c

@@ -941,7 +941,7 @@ mp_obj_t mp_obj_str_format(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwa
                     }
                 }
                 lookup = str_to_int(field, &index) + field;
-                if (index >= n_args - 1) {
+                if ((uint)index >= n_args - 1) {
                     nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
                 }
                 arg = args[index + 1];
@@ -969,7 +969,7 @@ mp_obj_t mp_obj_str_format(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwa
                         "can't switch from manual field specification to automatic field numbering"));
                 }
             }
-            if (arg_i >= n_args - 1) {
+            if ((uint)arg_i >= n_args - 1) {
                 nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "tuple index out of range"));
             }
             arg = args[arg_i + 1];
@@ -1248,7 +1248,7 @@ mp_obj_t mp_obj_str_format(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwa
                     if (precision < 0) {
                         precision = len;
                     }
-                    if (len > precision) {
+                    if (len > (mp_uint_t)precision) {
                         len = precision;
                     }
                     pfenv_print_strn(&pfenv_vstr, s, len, flags, fill, width);
@@ -1334,7 +1334,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_o
         int width = 0;
         if (str < top) {
             if (*str == '*') {
-                if (arg_i >= n_args) {
+                if ((uint)arg_i >= n_args) {
                     goto not_enough_args;
                 }
                 width = mp_obj_get_int(args[arg_i++]);
@@ -1347,7 +1347,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_o
         if (str < top && *str == '.') {
             if (++str < top) {
                 if (*str == '*') {
-                    if (arg_i >= n_args) {
+                    if ((uint)arg_i >= n_args) {
                         goto not_enough_args;
                     }
                     prec = mp_obj_get_int(args[arg_i++]);
@@ -1370,7 +1370,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_o
 
         // Tuple value lookup
         if (arg == MP_OBJ_NULL) {
-            if (arg_i >= n_args) {
+            if ((uint)arg_i >= n_args) {
 not_enough_args:
                 nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "not enough arguments for format string"));
             }
@@ -1429,7 +1429,7 @@ not_enough_args:
                 if (prec < 0) {
                     prec = len;
                 }
-                if (len > prec) {
+                if (len > (uint)prec) {
                     len = prec;
                 }
                 pfenv_print_strn(&pfenv_vstr, vstr_str(arg_vstr), len, flags, ' ', width);
@@ -1453,7 +1453,7 @@ not_enough_args:
         }
     }
 
-    if (arg_i != n_args) {
+    if ((uint)arg_i != n_args) {
         nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "not all arguments converted during string formatting"));
     }
 
@@ -1522,7 +1522,7 @@ STATIC mp_obj_t str_replace(mp_uint_t n_args, const mp_obj_t *args) {
             replaced_str_index += new_len;
             num_replacements_done++;
         }
-        while (num_replacements_done != max_rep && str_len_remain > 0 && (old_occurrence = find_subbytes(offset_ptr, str_len_remain, old, old_len, 1)) != NULL) {
+        while (num_replacements_done != (mp_uint_t)max_rep && str_len_remain > 0 && (old_occurrence = find_subbytes(offset_ptr, str_len_remain, old, old_len, 1)) != NULL) {
             if (old_len == 0) {
                 old_occurrence += 1;
             }

py/parse.c

@@ -316,7 +316,7 @@ STATIC void push_result_token(parser_t *parser) {
         for (; i < len; i++) {
             mp_uint_t dig;
             int clower = str[i] | 0x20;
-            if (unichar_isdigit(str[i]) && str[i] - '0' < base) {
+            if (unichar_isdigit(str[i]) && (mp_uint_t)(str[i] - '0') < base) {
                 dig = str[i] - '0';
             } else if (base == 16 && 'a' <= clower && clower <= 'f') {
                 dig = clower - 'a' + 10;

py/pfenv.c

@@ -341,12 +341,15 @@ int pfenv_print_float(const pfenv_t *pfenv, mp_float_t f, char fmt, int flags, c
     *fmt_s = '\0';
 
     len = snprintf(buf, sizeof(buf), fmt_buf, prec, f);
+    if (len < 0) {
+        len = 0;
+    }
 #else
 #error Unknown MICROPY FLOAT IMPL
 #endif
     char *s = buf;
 
-    if ((flags & PF_FLAG_ADD_PERCENT) && (len + 1) < sizeof(buf)) {
+    if ((flags & PF_FLAG_ADD_PERCENT) && (size_t)(len + 1) < sizeof(buf)) {
         buf[len++] = '%';
         buf[len] = '\0';
     }

py/qstr.c

@@ -49,7 +49,7 @@
 //  - data follows
 //  - \0 terminated (for now, so they can be printed using printf)
 
-#define Q_GET_HASH(q)   ((q)[0] | ((q)[1] << 8))
+#define Q_GET_HASH(q)   ((mp_uint_t)(q)[0] | ((mp_uint_t)(q)[1] << 8))
 #define Q_GET_ALLOC(q)  (2 + MICROPY_QSTR_BYTES_IN_LEN + Q_GET_LENGTH(q) + 1)
 #define Q_GET_DATA(q)   ((q) + 2 + MICROPY_QSTR_BYTES_IN_LEN)
 #if MICROPY_QSTR_BYTES_IN_LEN == 1

py/runtime.c

@@ -334,7 +334,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                     if (rhs_val < 0) {
                         // negative shift not allowed
                         nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
-                    } else if (rhs_val >= BITS_PER_WORD || lhs_val > (MP_SMALL_INT_MAX >> rhs_val) || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
+                    } else if (rhs_val >= (mp_int_t)BITS_PER_WORD || lhs_val > (MP_SMALL_INT_MAX >> rhs_val) || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
                         // left-shift will overflow, so use higher precision integer
                         lhs = mp_obj_new_int_from_ll(lhs_val);
                         goto generic_binary_op;
@@ -351,7 +351,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                         nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
                     } else {
                         // standard precision is enough for right-shift
-                        if (rhs_val >= BITS_PER_WORD) {
+                        if (rhs_val >= (mp_int_t)BITS_PER_WORD) {
                             // Shifting to big amounts is underfined behavior
                             // in C and is CPU-dependent; propagate sign bit.
                             rhs_val = BITS_PER_WORD - 1;

py/sequence.c

@@ -70,12 +70,12 @@ bool mp_seq_get_fast_slice_indexes(mp_uint_t len, mp_obj_t slice, mp_bound_slice
         if (start < 0) {
             start = 0;
         }
-    } else if (start > len) {
+    } else if ((mp_uint_t)start > len) {
         start = len;
     }
     if (stop < 0) {
         stop = len + stop;
-    } else if (stop > len) {
+    } else if ((mp_uint_t)stop > len) {
         stop = len;
     }
 

py/showbc.c

@@ -81,7 +81,7 @@ void mp_bytecode_print(const void *descr, mp_uint_t n_total_args, const byte *ip
 
     // bytecode prelude: arg names (as qstr objects)
     printf("arg names:");
-    for (int i = 0; i < n_total_args; i++) {
+    for (mp_uint_t i = 0; i < n_total_args; i++) {
         printf(" %s", qstr_str(MP_OBJ_QSTR_VALUE(*(mp_obj_t*)ip)));
         ip += sizeof(mp_obj_t);
     }
@@ -539,7 +539,7 @@ const byte *mp_bytecode_print_str(const byte *ip) {
 
 void mp_bytecode_print2(const byte *ip, mp_uint_t len) {
     mp_showbc_code_start = ip;
-    while (ip - mp_showbc_code_start < len) {
+    while (ip < len + mp_showbc_code_start) {
         printf("%02u ", (uint)(ip - mp_showbc_code_start));
         ip = mp_bytecode_print_str(ip);
         printf("\n");

py/vstr.c

@@ -350,7 +350,7 @@ void vstr_vprintf(vstr_t *vstr, const char *fmt, va_list ap) {
         va_end(ap2);
 
         // if that worked, return
-        if (n > -1 && n < size) {
+        if (n > -1 && (size_t)n < size) {
             vstr->len += n;
             return;
         }

unix/main.c

@@ -355,7 +355,7 @@ int main(int argc, char **argv) {
     mp_obj_list_get(mp_sys_path, &path_num, &path_items);
     path_items[0] = MP_OBJ_NEW_QSTR(MP_QSTR_);
     char *p = path;
-    for (int i = 1; i < path_num; i++) {
+    for (mp_uint_t i = 1; i < path_num; i++) {
         char *p1 = strchr(p, PATHLIST_SEP_CHAR);
         if (p1 == NULL) {
             p1 = p + strlen(p);
@@ -364,7 +364,7 @@ int main(int argc, char **argv) {
             // Expand standalone ~ to $HOME
             CHECKBUF(buf, PATH_MAX);
             CHECKBUF_APPEND(buf, home, strlen(home));
-            CHECKBUF_APPEND(buf, p + 1, p1 - p - 1);
+            CHECKBUF_APPEND(buf, p + 1, (size_t)(p1 - p - 1));
             path_items[i] = MP_OBJ_NEW_QSTR(qstr_from_strn(buf, CHECKBUF_LEN(buf)));
         } else {
             path_items[i] = MP_OBJ_NEW_QSTR(qstr_from_strn(p, p1 - p));

unix/modffi.c

@@ -206,7 +206,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(ffimod_func_obj, 4, 4, ffimod_func);
 
 STATIC void call_py_func(ffi_cif *cif, void *ret, void** args, mp_obj_t func) {
     mp_obj_t pyargs[cif->nargs];
-    for (int i = 0; i < cif->nargs; i++) {
+    for (uint i = 0; i < cif->nargs; i++) {
         pyargs[i] = mp_obj_new_int(*(mp_int_t*)args[i]);
     }
     mp_obj_t res = mp_call_function_n_kw(func, cif->nargs, 0, pyargs);
@@ -309,8 +309,7 @@ STATIC mp_obj_t ffifunc_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw,
 
     ffi_arg values[n_args];
     void *valueptrs[n_args];
-    int i;
-    for (i = 0; i < n_args; i++) {
+    for (uint i = 0; i < n_args; i++) {
         mp_obj_t a = args[i];
         if (a == mp_const_none) {
             values[i] = 0;