1 files changed, 97 insertions, 0 deletions
diff --git a/libcxx/test/std/utilities/charconv/charconv.to.chars/integral.pass.cpp b/libcxx/test/std/utilities/charconv/charconv.to.chars/integral.pass.cpp
index 4bfe27d6dac..e30d3c84909 100644
--- a/libcxx/test/std/utilities/charconv/charconv.to.chars/integral.pass.cpp
+++ b/libcxx/test/std/utilities/charconv/charconv.to.chars/integral.pass.cpp
@@ -45,6 +45,56 @@ struct test_basics : to_chars_test_base<T>
         test(0xdeadbeaf, "deadbeaf", 16);
         test(0755, "755", 8);
 
+        // Test each len till len of UINT64_MAX = 20 because to_chars algorithm
+        // makes branches based on decimal digits count in the value string
+        // representation.
+        // Test driver automatically skips values not fitting into source type.
+        test(1UL, "1");
+        test(12UL, "12");
+        test(123UL, "123");
+        test(1234UL, "1234");
+        test(12345UL, "12345");
+        test(123456UL, "123456");
+        test(1234567UL, "1234567");
+        test(12345678UL, "12345678");
+        test(123456789UL, "123456789");
+        test(1234567890UL, "1234567890");
+        test(12345678901UL, "12345678901");
+        test(123456789012UL, "123456789012");
+        test(1234567890123UL, "1234567890123");
+        test(12345678901234UL, "12345678901234");
+        test(123456789012345UL, "123456789012345");
+        test(1234567890123456UL, "1234567890123456");
+        test(12345678901234567UL, "12345678901234567");
+        test(123456789012345678UL, "123456789012345678");
+        test(1234567890123456789UL, "1234567890123456789");
+        test(12345678901234567890UL, "12345678901234567890");
+
+        // Test special cases with zeros inside a value string representation,
+        // to_chars algorithm processes them in a special way and should not
+        // skip trailing zeros
+        // Test driver automatically skips values not fitting into source type.
+        test(0UL, "0");
+        test(10UL, "10");
+        test(100UL, "100");
+        test(1000UL, "1000");
+        test(10000UL, "10000");
+        test(100000UL, "100000");
+        test(1000000UL, "1000000");
+        test(10000000UL, "10000000");
+        test(100000000UL, "100000000");
+        test(1000000000UL, "1000000000");
+        test(10000000000UL, "10000000000");
+        test(100000000000UL, "100000000000");
+        test(1000000000000UL, "1000000000000");
+        test(10000000000000UL, "10000000000000");
+        test(100000000000000UL, "100000000000000");
+        test(1000000000000000UL, "1000000000000000");
+        test(10000000000000000UL, "10000000000000000");
+        test(100000000000000000UL, "100000000000000000");
+        test(1000000000000000000UL, "1000000000000000000");
+        test(10000000000000000000UL, "10000000000000000000");
+
         for (int b = 2; b < 37; ++b)
         {
             using xl = std::numeric_limits<T>;
@@ -73,6 +123,53 @@ struct test_signed : to_chars_test_base<T>
         test(-2647, "-101001010111", 2);
         test(-0xcc1, "-cc1", 16);
 
+        // Test each len till len of INT64_MAX = 19 because to_chars algorithm
+        // makes branches based on decimal digits count in the value string
+        // representation.
+        // Test driver automatically skips values not fitting into source type.
+        test(-1L, "-1");
+        test(-12L, "-12");
+        test(-123L, "-123");
+        test(-1234L, "-1234");
+        test(-12345L, "-12345");
+        test(-123456L, "-123456");
+        test(-1234567L, "-1234567");
+        test(-12345678L, "-12345678");
+        test(-123456789L, "-123456789");
+        test(-1234567890L, "-1234567890");
+        test(-12345678901L, "-12345678901");
+        test(-123456789012L, "-123456789012");
+        test(-1234567890123L, "-1234567890123");
+        test(-12345678901234L, "-12345678901234");
+        test(-123456789012345L, "-123456789012345");
+        test(-1234567890123456L, "-1234567890123456");
+        test(-12345678901234567L, "-12345678901234567");
+        test(-123456789012345678L, "-123456789012345678");
+        test(-1234567890123456789L, "-1234567890123456789");
+
+        // Test special cases with zeros inside a value string representation,
+        // to_chars algorithm processes them in a special way and should not
+        // skip trailing zeros
+        // Test driver automatically skips values not fitting into source type.
+        test(-10L, "-10");
+        test(-100L, "-100");
+        test(-1000L, "-1000");
+        test(-10000L, "-10000");
+        test(-100000L, "-100000");
+        test(-1000000L, "-1000000");
+        test(-10000000L, "-10000000");
+        test(-100000000L, "-100000000");
+        test(-1000000000L, "-1000000000");
+        test(-10000000000L, "-10000000000");
+        test(-100000000000L, "-100000000000");
+        test(-1000000000000L, "-1000000000000");
+        test(-10000000000000L, "-10000000000000");
+        test(-100000000000000L, "-100000000000000");
+        test(-1000000000000000L, "-1000000000000000");
+        test(-10000000000000000L, "-10000000000000000");
+        test(-100000000000000000L, "-100000000000000000");
+        test(-1000000000000000000L, "-1000000000000000000");
+
         for (int b = 2; b < 37; ++b)
         {
             using xl = std::numeric_limits<T>;