Fixes found with -ffreestanding disabled

arch/xtensa/core/fatal.c

@@ -118,6 +118,7 @@ void exit(int return_code)
 	LOG_ERR("exit(%d)", return_code);
 	k_panic();
 #endif
+	CODE_UNREACHABLE;
 }
 
 #ifdef XT_SIMULATOR

cmake/compiler/clang/compiler_flags.cmake

@@ -27,6 +27,7 @@ set_compiler_property(PROPERTY warning_base
                       -Wformat-security
                       -Wno-format-zero-length
                       -Wno-main
+                      -Wno-unused-but-set-variable
                       -Wno-typedef-redefinition
 )
 

drivers/flash/flash_ite_it8xxx2.c

@@ -23,7 +23,7 @@
 LOG_MODULE_REGISTER(flash_ite_it8xxx2);
 
 /* RAM code start address */
-extern char _ram_code_start;
+extern char _ram_code_start[];
 #define FLASH_RAMCODE_START ((uint32_t)&_ram_code_start)
 #define	FLASH_RAMCODE_START_BIT19      BIT(19)
 /* RAM code section */

drivers/sensor/adxl372/adxl372.c

@@ -643,16 +643,19 @@ static int adxl372_attr_set_thresh(const struct device *dev,
 {
 	const struct adxl372_dev_config *cfg = dev->config;
 	struct adxl372_activity_threshold threshold;
+	int64_t llvalue;
 	int32_t value;
 	int64_t micro_ms2 = val->val1 * 1000000LL + val->val2;
 	uint8_t reg;
 
-	value = abs((micro_ms2 * 10) / SENSOR_G);
+	llvalue = llabs((micro_ms2 * 10) / SENSOR_G);
 
-	if (value > 2047) {
+	if (llvalue > 2047) {
 		return -EINVAL;
 	}
 
+	value = (int32_t) llvalue;
+
 	threshold.thresh = value;
 	threshold.enable = cfg->activity_th.enable;
 	threshold.referenced = cfg->activity_th.referenced;

drivers/serial/uart_native_posix.c

@@ -129,37 +129,39 @@ static int open_tty(struct native_uart_status *driver_data,
 		err_nbr = errno;
 		close(master_pty);
 		ERROR("Could not grant access to the slave PTY side (%i)\n",
-			errno);
+			err_nbr);
 	}
 	ret = unlockpt(master_pty);
 	if (ret == -1) {
 		err_nbr = errno;
 		close(master_pty);
-		ERROR("Could not unlock the slave PTY side (%i)\n", errno);
+		ERROR("Could not unlock the slave PTY side (%i)\n", err_nbr);
 	}
 	slave_pty_name = ptsname(master_pty);
 	if (slave_pty_name == NULL) {
 		err_nbr = errno;
 		close(master_pty);
-		ERROR("Error getting slave PTY device name (%i)\n", errno);
+		ERROR("Error getting slave PTY device name (%i)\n", err_nbr);
 	}
 	/* Set the master PTY as non blocking */
 	flags = fcntl(master_pty, F_GETFL);
 	if (flags == -1) {
 		err_nbr = errno;
 		close(master_pty);
 		ERROR("Could not read the master PTY file status flags (%i)\n",
-			errno);
+			err_nbr);
 	}
 
 	ret = fcntl(master_pty, F_SETFL, flags | O_NONBLOCK);
 	if (ret == -1) {
 		err_nbr = errno;
 		close(master_pty);
 		ERROR("Could not set the master PTY as non-blocking (%i)\n",
-			errno);
+			err_nbr);
 	}
 
+	(void) err_nbr;
+
 	/*
 	 * Set terminal in "raw" mode:
 	 *  Not canonical (no line input)
@@ -291,6 +293,7 @@ static void np_uart_poll_out(const struct device *dev,
 	 * but we do not need the return value for anything.
 	 */
 	ret = write(d->out_fd, &out_char, 1);
+	(void) ret;
 }
 
 /**

samples/subsys/logging/syst/src/main.c

@@ -117,7 +117,7 @@ void log_msgs(void)
 #endif
 }
 
-void main(void)
+int main(void)
 {
 	log_msgs();
 
@@ -140,5 +140,5 @@ void main(void)
 	/* raw string */
 	printk("SYST Sample Execution Completed\n");
 #endif
-
+	return 0;
 }

subsys/usb/device/class/hid/core.c

@@ -327,8 +327,8 @@ void hid_sof_handler(struct hid_device_info *dev_data)
 			continue;
 		}
 
-		uint32_t diff = abs(dev_data->idle_rate[i] * 4U -
-				    dev_data->sof_cnt[i]);
+		int32_t diff = abs((int32_t) ((uint32_t) dev_data->idle_rate[i] * 4U -
+					      dev_data->sof_cnt[i]));
 
 		if (diff < 2 && reported == false) {
 			dev_data->sof_cnt[i] = 0U;

tests/kernel/timer/timer_api/src/main.c

@@ -17,7 +17,7 @@ struct timer_data {
 #define DURATION 100
 #define PERIOD 50
 #define EXPIRE_TIMES 4
-#define WITHIN_ERROR(var, target, epsilon) (abs((target) - (var)) <= (epsilon))
+#define WITHIN_ERROR(var, target, epsilon) (llabs((int64_t) ((target) - (var))) <= (epsilon))
 
 /* ms can be converted precisely to ticks only when a ms is exactly
  * represented by an integral number of ticks.  If the conversion is
@@ -104,7 +104,7 @@ static bool interval_check(int64_t interval, int64_t desired)
 		slop += 2 * k_ticks_to_ms_ceil32(1);
 	}
 
-	if (abs(interval - desired) > slop) {
+	if (!WITHIN_ERROR(interval, desired, slop)) {
 		return false;
 	}
 

tests/lib/newlib/heap_listener/src/main.c

@@ -35,6 +35,8 @@ static void heap_resized(uintptr_t heap_id, void *old_heap_end, void *new_heap_e
 
 static HEAP_LISTENER_RESIZE_DEFINE(listener, HEAP_ID_LIBC, heap_resized);
 
+void *ptr;
+
 /**
  * @brief Test that heap listener is notified when libc heap size changes.
  *
@@ -45,7 +47,6 @@ static HEAP_LISTENER_RESIZE_DEFINE(listener, HEAP_ID_LIBC, heap_resized);
 void test_alloc_and_trim(void)
 {
 	uintptr_t saved_heap_end;
-	void *ptr;
 
 	TC_PRINT("Allocating memory...\n");