[libc-commits] [libc] [libc] Support C23 'b' (binary) modifier in printf (PR #80851)

[via libc-commits]

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@@ -410,6 +410,115 @@ TEST(LlvmLibcSPrintfTest, HexConv) {
   ASSERT_STREQ(buff, "007F 0x1000000000 002   ");
 }
 
+TEST(LlvmLibcSPrintfTest, BinConv) {
+  char buff[64];
+  int written;
+
+  // Basic Tests.
+
+  written = LIBC_NAMESPACE::sprintf(buff, "%b", 42);
+  EXPECT_EQ(written, 6);
+  ASSERT_STREQ(buff, "101010");
+
+  written = LIBC_NAMESPACE::sprintf(buff, "%B", 12081991);
+  EXPECT_EQ(written, 24);
+  ASSERT_STREQ(buff, "101110000101101101000111");
+
+  // Min Width Tests.
+
+  written = LIBC_NAMESPACE::sprintf(buff, "%10b", 0b101010);
+  EXPECT_EQ(written, 10);
+  ASSERT_STREQ(buff, "    101010");
+
+  written = LIBC_NAMESPACE::sprintf(buff, "%2B", 0b101010);
+  EXPECT_EQ(written, 6);
+  ASSERT_STREQ(buff, "101010");
+
+  // Precision Tests.
----------------
michaelrj-google wrote:

nit: It would be good to have a test where the precision equals the number of digits, such as ("%3b", 0b111) -> "111"

https://github.com/llvm/llvm-project/pull/80851