tree-wide: add the NONSTRING attribute where needed

This declares all char arrays that intentionally are lacking the
terminated zero byte as `NONSTRING`.

sys/fmt/fmt.c

@@ -27,12 +27,14 @@
 #include <time.h>
 #include <unistd.h>
 
+#include "compiler_hints.h"
 #include "container.h"
 #include "fmt.h"
 #include "modules.h"
 
 extern ssize_t stdio_write(const void* buffer, size_t len);
 
+NONSTRING
 static const char _hex_chars[16] = "0123456789ABCDEF";
 
 static const uint32_t _tenmap[] = {

sys/fmt/table.c

@@ -24,9 +24,11 @@
 #include <unistd.h>
 #include <string.h>
 
+#include "compiler_hints.h"
 #include "fmt.h"
 #include "fmt_table.h"
 
+NONSTRING
 static const char fmt_table_spaces[16] = "                ";
 
 /**

tests/bench/sys_base64/main.c

@@ -22,15 +22,20 @@
 #include <string.h>
 
 #include "base64.h"
+#include "compiler_hints.h"
 #include "fmt.h"
 #include "macros/utils.h"
 #include "xtimer.h"
 
 static char buf[128];
 
+/* no need for the zero-termination here, base64_encode() gets the size of the
+ * string as explicit argument */
+NONSTRING
 static const char input[96] = "This is an extremely, enormously, greatly, "
                               "immensely, tremendously, remarkably lengthy "
                               "sentence!";
+NONSTRING
 static const char base64[128] =
 "VGhpcyBpcyBhbiBleHRyZW1lbHksIGVub3Jtb3VzbHksIGdyZWF0bHksIGltbWVuc2VseSwgdHJl"
 "bWVuZG91c2x5LCByZW1hcmthYmx5IGxlbmd0aHkgc2VudGVuY2Uh";

tests/sys/psa_crypto/main.c

@@ -20,6 +20,7 @@
 
 #include <stdio.h>
 #include "embUnit.h"
+#include "compiler_hints.h"
 #include "psa/crypto.h"
 
 void addFailurePSA(const char *func, psa_status_t errcode, long line, const char *file)
@@ -73,7 +74,9 @@ static void test_hash_interleaved(void)
 {
     const psa_algorithm_t alg = PSA_ALG_SHA_256;
 
+    NONSTRING
     const uint8_t in1[1] = "a";
+    NONSTRING
     const uint8_t in2[1] = "b";
 
     const uint8_t exp1[] = {

tests/sys/psa_crypto_ecdsa/test_ecdsa_p256_vectors.c

@@ -20,6 +20,7 @@
 #include <stdio.h>
 #include <stdint.h>
 
+#include "compiler_hints.h"
 #include "psa/crypto.h"
 
 /*
@@ -42,6 +43,7 @@ static const uint8_t public_key[] = {0x04, 0x60, 0xFE, 0xD4, 0xBA, 0x25, 0x5A, 0
 
 /* certain PSA backends require the data to be in RAM rather than ROM
  * so these values cannot be `const` */
+NONSTRING
 static uint8_t message[6] = "sample";
 static uint8_t signature[] = {0xEF, 0xD4, 0x8B, 0x2A, 0xAC, 0xB6, 0xA8, 0xFD, 0x11, 0x40,
     0xDD, 0x9C, 0xD4, 0x5E, 0x81, 0xD6, 0x9D, 0x2C, 0x87, 0x7B, 0x56, 0xAA, 0xF9, 0x91, 0xC3, 0x4D,

tests/sys/struct_tm_utility/main.c

@@ -29,17 +29,21 @@
 #include <stdlib.h>
 #include <stdbool.h>
 
+#include "compiler_hints.h"
 #include "shell.h"
 #include "tm.h"
 
+NONSTRING
 static const char MON_NAMES[12][3] = {
     "JAN", "FEB", "MAR", "APR",
     "MAY", "JUN", "JUL", "AUG",
     "SEP", "OCT", "NOV", "DEC",
 };
+NONSTRING
 static const char DAY_NAMES[7][3] = {
     "SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"
 };
+NONSTRING
 static const char BOOL_NAMES[2][3] = { "NO", "YES" };
 
 bool proper_atoi(const char *a, int *i)

tests/unittests/tests-fmt/tests-fmt.c

@@ -17,6 +17,7 @@
 
 #include "embUnit/embUnit.h"
 
+#include "compiler_hints.h"
 #include "fmt.h"
 #include "tests-fmt.h"
 
@@ -244,6 +245,7 @@ static void test_fmt_hex_bytes(void)
 
 static void test_fmt_u16_hex(void)
 {
+    NONSTRING
     char out[8] = "zzzzzzzz";
 
     /* Check return count with null buffer input */
@@ -260,6 +262,7 @@ static void test_fmt_u16_hex(void)
 
 static void test_fmt_u32_hex(void)
 {
+    NONSTRING
     char out[12] = "zzzzzzzzzzzz";
 
     /* Check return count with null buffer input */
@@ -276,6 +279,7 @@ static void test_fmt_u32_hex(void)
 
 static void test_fmt_u64_hex(void)
 {
+    NONSTRING
     char out[20] = "zzzzzzzzzzzzzzzzzzzz";
 
     /* Check return count with null buffer input */
@@ -292,6 +296,7 @@ static void test_fmt_u64_hex(void)
 
 static void test_fmt_u16_dec(void)
 {
+    NONSTRING
     char out[8] = "zzzzzzzz";
     uint8_t chars = 0;
 
@@ -310,6 +315,7 @@ static void test_fmt_u16_dec(void)
 
 static void test_fmt_u32_dec(void)
 {
+    NONSTRING
     char out[16] = "zzzzzzzzzzzzzzzz";
     uint8_t chars = 0;
 
@@ -329,6 +335,7 @@ static void test_fmt_u32_dec(void)
 
 static void test_fmt_u64_dec(void)
 {
+    NONSTRING
     char out[24] = "zzzzzzzzzzzzzzzzzzzzzzzz";
     uint8_t chars = 0;
 
@@ -345,6 +352,7 @@ static void test_fmt_u64_dec(void)
 
 static void test_fmt_u64_dec_zero(void)
 {
+    NONSTRING
     char out[24] = "zzzzzzzzzzzzzzzzzzzzzzzz";
     uint8_t chars = 0;
 
@@ -355,6 +363,7 @@ static void test_fmt_u64_dec_zero(void)
 
 static void test_fmt_u64_dec_u64max(void)
 {
+    NONSTRING
     char out[24] = "zzzzzzzzzzzzzzzzzzzzzzzz";
     uint8_t chars = 0;