[libc-commits] [libc] [libc] Support %lc in printf (PR #169983)

[Alexey Samsonov via libc-commits]

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@@ -3487,3 +3492,61 @@ TEST(LlvmLibcSPrintfTest, IndexModeParsing) {
                    "why would u do this, this is such   a pain. %");
 }
 #endif // LIBC_COPT_PRINTF_DISABLE_INDEX_MODE
+
+#ifndef LIBC_COPT_PRINTF_DISABLE_WIDE
+TEST(LlvmLibcSprintfTest, WideCharConversion) {
+  char buff[16];
+  int written;
+
+  // Euro sign is a 3-byte UTF-8 character.
+  written = LIBC_NAMESPACE::sprintf(buff, "%lc", static_cast<wchar_t>(L'€'));
+  EXPECT_EQ(written, 3);
+  ASSERT_STREQ_LEN(written, buff, "€");
+
+  // Euro sign right justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%-4lc", static_cast<wchar_t>(L'€'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "€ ");
+
+  // Euro sign left justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%4lc", static_cast<wchar_t>(L'€'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, " €");
+
+  // Grinning face emoji is a 4-byte UTF-8 character.
+  written = LIBC_NAMESPACE::sprintf(buff, "%lc", static_cast<wchar_t>(L'😀'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "😀");
+
+  // Grinning face emoji left justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%-4lc", static_cast<wchar_t>(L'😀'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "😀");
+
+  // Grinning face emoji right justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%4lc", static_cast<wchar_t>(L'😀'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "😀");
+
+  // Grinning face emoji with smaller width, left justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%-3lc", static_cast<wchar_t>(L'😀'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "😀");
+
+  // Grinning face emoji with smaller width, right justified.
+  written = LIBC_NAMESPACE::sprintf(buff, "%3lc", static_cast<wchar_t>(L'😀'));
+  EXPECT_EQ(written, 4);
+  ASSERT_STREQ_LEN(written, buff, "😀");
+
+  // WEOF test.
+  written = LIBC_NAMESPACE::sprintf(buff, "%lc", static_cast<wchar_t>(WEOF));
+  EXPECT_EQ(written, -1);
+  EXPECT_EQ(static_cast<int>(libc_errno), EILSEQ);
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vonosmas wrote:

You should be using `ASSERT_ERRNO_EQ` macro, since it not only validates libc_errno, but also clears it out. Same below.

https://github.com/llvm/llvm-project/pull/169983