[libc-commits] [libc] [libc] Support %lc in printf (PR #169983)
Shubh Pachchigar via libc-commits
libc-commits at lists.llvm.org
Sat Dec 6 22:58:42 PST 2025
https://github.com/shubhe25p updated https://github.com/llvm/llvm-project/pull/169983
>From 7a33e23a7b5a94500ed62dc7cc9487c873ac4bf6 Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Wed, 3 Dec 2025 00:44:15 -0800
Subject: [PATCH 1/8] init
---
libc/src/stdio/printf_core/CMakeLists.txt | 5 ++
libc/src/stdio/printf_core/char_converter.h | 29 ++++++-
libc/src/stdio/printf_core/parser.h | 13 ++-
.../test/src/stdio/printf_core/CMakeLists.txt | 2 +
.../src/stdio/printf_core/converter_test.cpp | 82 ++++++++++++++++++-
.../src/stdio/printf_core/parser_test.cpp | 19 +++++
6 files changed, 142 insertions(+), 8 deletions(-)
diff --git a/libc/src/stdio/printf_core/CMakeLists.txt b/libc/src/stdio/printf_core/CMakeLists.txt
index 624129b2b36e7..798e8706b5331 100644
--- a/libc/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/src/stdio/printf_core/CMakeLists.txt
@@ -67,6 +67,7 @@ add_header_library(
parser.h
DEPENDS
.core_structs
+ libc.hdr.types.wint_t.h
libc.src.__support.arg_list
libc.src.__support.ctype_utils
libc.src.__support.str_to_integer
@@ -111,6 +112,8 @@ add_header_library(
.printf_config
.writer
libc.include.inttypes
+ libc.hdr.types.wchar_t
+ libc.hdr.types.wint_t
libc.src.__support.big_int
libc.src.__support.common
libc.src.__support.CPP.limits
@@ -123,6 +126,8 @@ add_header_library(
libc.src.__support.integer_to_string
libc.src.__support.libc_assert
libc.src.__support.uint128
+ libc.src.__support.wchar.mbstate
+ libc.src.__support.wchar.wcrtomb
libc.src.__support.StringUtil.error_to_string
libc.src.string.memory_utils.inline_memcpy
)
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index fd2eb2553887a..43d3ebb70e708 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -1,4 +1,4 @@
-//===-- String Converter for printf -----------------------------*- C++ -*-===//
+//===-- Character Converter for printf --------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -9,7 +9,11 @@
#ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CHAR_CONVERTER_H
#define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CHAR_CONVERTER_H
+#include "hdr/types/wchar_t.h"
+#include "hdr/types/wint_t.h"
#include "src/__support/macros/config.h"
+#include "src/__support/wchar/mbstate.h"
+#include "src/__support/wchar/wcrtomb.h"
#include "src/stdio/printf_core/converter_utils.h"
#include "src/stdio/printf_core/core_structs.h"
#include "src/stdio/printf_core/writer.h"
@@ -21,7 +25,6 @@ template <WriteMode write_mode>
LIBC_INLINE int convert_char(Writer<write_mode> *writer,
const FormatSection &to_conv) {
char c = static_cast<char>(to_conv.conv_val_raw);
-
constexpr int STRING_LEN = 1;
size_t padding_spaces =
@@ -33,7 +36,27 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
RET_IF_RESULT_NEGATIVE(writer->write(' ', padding_spaces));
}
- RET_IF_RESULT_NEGATIVE(writer->write(c));
+ if (to_conv.length_modifier == LengthModifier::l) {
+ wint_t wi = static_cast<wint_t>(to_conv.conv_val_raw);
+
+ if (wi == WEOF) {
+ return -1;
+ }
+
+ char mb_str[MB_LEN_MAX];
+ internal::mbstate mbstate;
+ wchar_t wc = static_cast<wchar_t>(wi);
+
+ auto ret = internal::wcrtomb(mb_str, wc, &internal_mbstate);
+ if (!ret.has_value()) {
+ return -1;
+ }
+
+ RET_IF_RESULT_NEGATIVE(writer->write({mb_str, ret.value()}));
+
+ } else {
+ RET_IF_RESULT_NEGATIVE(writer->write(c));
+ }
// If the padding is on the right side, write the spaces last.
if (padding_spaces > 0 &&
diff --git a/libc/src/stdio/printf_core/parser.h b/libc/src/stdio/printf_core/parser.h
index cef9b1ae58fa0..dea1ff966b6bb 100644
--- a/libc/src/stdio/printf_core/parser.h
+++ b/libc/src/stdio/printf_core/parser.h
@@ -9,6 +9,7 @@
#ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_PARSER_H
#define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_PARSER_H
+#include "hdr/types/wint_t.h"
#include "include/llvm-libc-macros/stdfix-macros.h"
#include "src/__support/CPP/algorithm.h" // max
#include "src/__support/CPP/limits.h"
@@ -73,9 +74,9 @@ template <typename ArgProvider> class Parser {
ArgProvider args_cur;
#ifndef LIBC_COPT_PRINTF_DISABLE_INDEX_MODE
- // args_start stores the start of the va_args, which is allows getting the
- // value of arguments that have already been passed. args_index is tracked so
- // that we know which argument args_cur is on.
+ // args_start stores the start of the va_args, which helps in getting the
+ // number of arguments that have already been passed. args_index is tracked
+ // so that we know which argument args_cur is on.
ArgProvider args_start;
size_t args_index = 1;
@@ -173,7 +174,11 @@ template <typename ArgProvider> class Parser {
section.has_conv = true;
break;
case ('c'):
- WRITE_ARG_VAL_SIMPLEST(section.conv_val_raw, int, conv_index);
+ if (section.length_modifier == LengthModifier::l) {
+ WRITE_ARG_VAL_SIMPLEST(section.conv_val_raw, wint_t, conv_index);
+ } else {
+ WRITE_ARG_VAL_SIMPLEST(section.conv_val_raw, int, conv_index);
+ }
break;
case ('d'):
case ('i'):
diff --git a/libc/test/src/stdio/printf_core/CMakeLists.txt b/libc/test/src/stdio/printf_core/CMakeLists.txt
index ff7ebbc4f5fd0..f65d2baef41c7 100644
--- a/libc/test/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/test/src/stdio/printf_core/CMakeLists.txt
@@ -7,6 +7,7 @@ add_libc_unittest(
LINK_LIBRARIES
LibcPrintfHelpers
DEPENDS
+ libc.hdr.types.wchar_t
libc.src.stdio.printf_core.parser
libc.src.stdio.printf_core.core_structs
libc.src.__support.CPP.string_view
@@ -32,6 +33,7 @@ add_libc_unittest(
SRCS
converter_test.cpp
DEPENDS
+ libc.hdr.types.wchar_t
libc.src.stdio.printf_core.converter
libc.src.stdio.printf_core.writer
libc.src.stdio.printf_core.core_structs
diff --git a/libc/test/src/stdio/printf_core/converter_test.cpp b/libc/test/src/stdio/printf_core/converter_test.cpp
index 2dae2a22c864c..296df9d9e6fa5 100644
--- a/libc/test/src/stdio/printf_core/converter_test.cpp
+++ b/libc/test/src/stdio/printf_core/converter_test.cpp
@@ -6,10 +6,10 @@
//
//===----------------------------------------------------------------------===//
+#include "hdr/types/wchar_t.h"
#include "src/stdio/printf_core/converter.h"
#include "src/stdio/printf_core/core_structs.h"
#include "src/stdio/printf_core/writer.h"
-
#include "test/UnitTest/Test.h"
class LlvmLibcPrintfConverterTest : public LIBC_NAMESPACE::testing::Test {
@@ -255,3 +255,83 @@ TEST_F(LlvmLibcPrintfConverterTest, OctConversion) {
ASSERT_STREQ(str, "1234");
ASSERT_EQ(writer.get_chars_written(), size_t{4});
}
+
+TEST_F(LlvmLibcPrintfConverterTest, WideCharConversion) {
+ LIBC_NAMESPACE::printf_core::FormatSection section;
+ section.has_conv = true;
+ section.raw_string = "%lc";
+ section.conv_name = 'c';
+ section.length_modifier = LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ section.conv_val_raw = static_cast<wchar_t>(L'€');
+
+ LIBC_NAMESPACE::printf_core::convert(&writer, section);
+
+ wb.buff[wb.buff_cur] = '\0';
+
+ ASSERT_STREQ(str, "€");
+ ASSERT_EQ(writer.get_chars_written(), size_t{1});
+}
+
+TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionLeftJustified) {
+ LIBC_NAMESPACE::printf_core::FormatSection left_justified_conv;
+ left_justified_conv.has_conv = true;
+ left_justified_conv.raw_string = "%-4lc";
+ left_justified_conv.conv_name = 'c';
+ left_justified_conv.length_modifier =
+ LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ left_justified_conv.flags =
+ LIBC_NAMESPACE::printf_core::FormatFlags::LEFT_JUSTIFIED;
+ left_justified_conv.min_width = 4;
+ left_justified_conv.conv_val_raw = static_cast<wchar_t>(L'€');
+
+ LIBC_NAMESPACE::printf_core::convert(&writer, left_justified_conv);
+ wb.buff[wb.buff_cur] = '\0';
+
+ ASSERT_STREQ(str, "€ ");
+ ASSERT_EQ(writer.get_chars_written(), size_t{4});
+}
+
+TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionRightJustified) {
+ LIBC_NAMESPACE::printf_core::FormatSection right_justified_conv;
+ right_justified_conv.has_conv = true;
+ right_justified_conv.raw_string = "%4lc";
+ right_justified_conv.conv_name = 'c';
+ right_justified_conv.length_modifier =
+ LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ right_justified_conv.min_width = 4;
+ right_justified_conv.conv_val_raw = static_cast<wchar_t>(L'€');
+
+ LIBC_NAMESPACE::printf_core::convert(&writer, right_justified_conv);
+ wb.buff[wb.buff_cur] = '\0';
+
+ ASSERT_STREQ(str, " €");
+ ASSERT_EQ(writer.get_chars_written(), size_t{4});
+}
+
+TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionInvalid) {
+ LIBC_NAMESPACE::printf_core::FormatSection section;
+ section.has_conv = true;
+ section.raw_string = "%lc";
+ section.conv_name = 'c';
+ section.length_modifier = LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ // An invalid wide character.
+ section.conv_val_raw = static_cast<wchar_t>(0xFFFFFFFF);
+
+ int ret = LIBC_NAMESPACE::printf_core::convert(&writer, section);
+
+ ASSERT_EQ(ret, -1);
+}
+
+TEST_F(LlvmLibcPrintfConverterTest, WideCharWEOFConversion) {
+ LIBC_NAMESPACE::printf_core::FormatSection section;
+ section.has_conv = true;
+ section.raw_string = "%lc";
+ section.conv_name = 'c';
+ section.length_modifier = LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ // WEOF value.
+ section.conv_val_raw = static_cast<wchar_t>(WEOF);
+
+ int ret = LIBC_NAMESPACE::printf_core::convert(&writer, section);
+
+ ASSERT_EQ(ret, -1);
+}
diff --git a/libc/test/src/stdio/printf_core/parser_test.cpp b/libc/test/src/stdio/printf_core/parser_test.cpp
index 9d192828860f7..b2edf2b61d992 100644
--- a/libc/test/src/stdio/printf_core/parser_test.cpp
+++ b/libc/test/src/stdio/printf_core/parser_test.cpp
@@ -6,6 +6,7 @@
//
//===----------------------------------------------------------------------===//
+#include "hdr/types/wchar_t.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/CPP/string_view.h"
#include "src/__support/arg_list.h"
@@ -370,6 +371,24 @@ TEST(LlvmLibcPrintfParserTest,
ASSERT_PFORMAT_EQ(expected, format_arr[0]);
}
+TEST(LlvmLibcPrintfParserTest, EvalOneArgWithWideCharacter) {
+ LIBC_NAMESPACE::printf_core::FormatSection format_arr[2];
+ const char *str = "%lc";
+ wchar_t arg1 = L'€';
+ evaluate(format_arr, str, arg1);
+
+ LIBC_NAMESPACE::printf_core::FormatSection expected;
+ expected.has_conv = true;
+
+ expected.raw_string = {str, 3};
+ expected.length_modifier = LIBC_NAMESPACE::printf_core::LengthModifier::l;
+ expected.conv_val_raw =
+ static_cast<LIBC_NAMESPACE::fputil::FPBits<double>::StorageType>(arg1);
+ expected.conv_name = 'c';
+
+ ASSERT_PFORMAT_EQ(expected, format_arr[0]);
+}
+
#ifndef LIBC_COPT_PRINTF_DISABLE_INDEX_MODE
TEST(LlvmLibcPrintfParserTest, IndexModeOneArg) {
>From a9c58577c6e98e1dcd3068202fcdfee532eff12e Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Wed, 3 Dec 2025 00:48:59 -0800
Subject: [PATCH 2/8] fix build
---
libc/src/stdio/printf_core/char_converter.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index 43d3ebb70e708..a05e9eb6f1a40 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -47,7 +47,7 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
internal::mbstate mbstate;
wchar_t wc = static_cast<wchar_t>(wi);
- auto ret = internal::wcrtomb(mb_str, wc, &internal_mbstate);
+ auto ret = internal::wcrtomb(mb_str, wc, &mbstate);
if (!ret.has_value()) {
return -1;
}
>From cef5d5bbf34b10da45ba8edf9c617b54144b2891 Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Thu, 4 Dec 2025 10:39:43 -0800
Subject: [PATCH 3/8] weof fix
---
libc/src/stdio/printf_core/CMakeLists.txt | 1 +
libc/src/stdio/printf_core/char_converter.h | 1 +
2 files changed, 2 insertions(+)
diff --git a/libc/src/stdio/printf_core/CMakeLists.txt b/libc/src/stdio/printf_core/CMakeLists.txt
index 798e8706b5331..6d1866ec755f2 100644
--- a/libc/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/src/stdio/printf_core/CMakeLists.txt
@@ -114,6 +114,7 @@ add_header_library(
libc.include.inttypes
libc.hdr.types.wchar_t
libc.hdr.types.wint_t
+ libc.hdr.wchar_macros
libc.src.__support.big_int
libc.src.__support.common
libc.src.__support.CPP.limits
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index a05e9eb6f1a40..e46507fb6d154 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -11,6 +11,7 @@
#include "hdr/types/wchar_t.h"
#include "hdr/types/wint_t.h"
+#include "hdr/wchar_macros.h"
#include "src/__support/macros/config.h"
#include "src/__support/wchar/mbstate.h"
#include "src/__support/wchar/wcrtomb.h"
>From a9e0814ee0d10ca905ce19b3a49bb7326c2a295f Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Thu, 4 Dec 2025 11:14:18 -0800
Subject: [PATCH 4/8] fix test errors
---
libc/test/src/stdio/printf_core/CMakeLists.txt | 1 +
libc/test/src/stdio/printf_core/converter_test.cpp | 7 ++++---
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/libc/test/src/stdio/printf_core/CMakeLists.txt b/libc/test/src/stdio/printf_core/CMakeLists.txt
index f65d2baef41c7..d3be991f9f226 100644
--- a/libc/test/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/test/src/stdio/printf_core/CMakeLists.txt
@@ -34,6 +34,7 @@ add_libc_unittest(
converter_test.cpp
DEPENDS
libc.hdr.types.wchar_t
+ libc.hdr.wchar_macros
libc.src.stdio.printf_core.converter
libc.src.stdio.printf_core.writer
libc.src.stdio.printf_core.core_structs
diff --git a/libc/test/src/stdio/printf_core/converter_test.cpp b/libc/test/src/stdio/printf_core/converter_test.cpp
index 296df9d9e6fa5..9476b799c9be3 100644
--- a/libc/test/src/stdio/printf_core/converter_test.cpp
+++ b/libc/test/src/stdio/printf_core/converter_test.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "hdr/types/wchar_t.h"
+#include "hdr/wchar_macros.h"
#include "src/stdio/printf_core/converter.h"
#include "src/stdio/printf_core/core_structs.h"
#include "src/stdio/printf_core/writer.h"
@@ -269,7 +270,7 @@ TEST_F(LlvmLibcPrintfConverterTest, WideCharConversion) {
wb.buff[wb.buff_cur] = '\0';
ASSERT_STREQ(str, "€");
- ASSERT_EQ(writer.get_chars_written(), size_t{1});
+ ASSERT_EQ(writer.get_chars_written(), size_t{3});
}
TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionLeftJustified) {
@@ -288,7 +289,7 @@ TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionLeftJustified) {
wb.buff[wb.buff_cur] = '\0';
ASSERT_STREQ(str, "€ ");
- ASSERT_EQ(writer.get_chars_written(), size_t{4});
+ ASSERT_EQ(writer.get_chars_written(), size_t{6});
}
TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionRightJustified) {
@@ -305,7 +306,7 @@ TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionRightJustified) {
wb.buff[wb.buff_cur] = '\0';
ASSERT_STREQ(str, " €");
- ASSERT_EQ(writer.get_chars_written(), size_t{4});
+ ASSERT_EQ(writer.get_chars_written(), size_t{6});
}
TEST_F(LlvmLibcPrintfConverterTest, WideCharConversionInvalid) {
>From 15a3e256a53bc30f6796d66bb2277e55e1e3edcb Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Sat, 6 Dec 2025 16:25:36 -0800
Subject: [PATCH 5/8] add snprintf test, flag for windows
---
libc/docs/dev/printf_behavior.rst | 6 +++
libc/src/stdio/printf_core/char_converter.h | 4 ++
libc/test/src/stdio/CMakeLists.txt | 2 +
libc/test/src/stdio/snprintf_test.cpp | 44 +++++++++++++++++++++
4 files changed, 56 insertions(+)
diff --git a/libc/docs/dev/printf_behavior.rst b/libc/docs/dev/printf_behavior.rst
index 01ab128a1f238..ec72113eff972 100644
--- a/libc/docs/dev/printf_behavior.rst
+++ b/libc/docs/dev/printf_behavior.rst
@@ -71,6 +71,12 @@ conversions (%r, %k); any fixed point number conversion will be treated as
invalid. This reduces code size. This has no effect if the current compiler does
not support fixed point numbers.
+LIBC_COPT_PRINTF_DISABLE_WCHAR_T
+--------------------------------
+When set, this flag disables support for wide characters (%lc). Any conversions
+will be ignored. This reduces code size. This will be set by default on windows
+platforms as current printf does not support UTF-16 wide characters.
+
LIBC_COPT_PRINTF_NO_NULLPTR_CHECKS
----------------------------------
When set, this flag disables the nullptr checks in %n and %s.
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index e46507fb6d154..4db6d44d94d7d 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -37,6 +37,7 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
RET_IF_RESULT_NEGATIVE(writer->write(' ', padding_spaces));
}
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
if (to_conv.length_modifier == LengthModifier::l) {
wint_t wi = static_cast<wint_t>(to_conv.conv_val_raw);
@@ -56,8 +57,11 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
RET_IF_RESULT_NEGATIVE(writer->write({mb_str, ret.value()}));
} else {
+ #endif // !LIBC_TARGET_OS_IS_WINDOWS
RET_IF_RESULT_NEGATIVE(writer->write(c));
+ #ifndef LIBC_TARGET_OS_IS_WINDOWS
}
+ #endif // !LIBC_TARGET_OS_IS_WINDOWS
// If the padding is on the right side, write the spaces last.
if (padding_spaces > 0 &&
diff --git a/libc/test/src/stdio/CMakeLists.txt b/libc/test/src/stdio/CMakeLists.txt
index a39428fb8d16c..22d593a682960 100644
--- a/libc/test/src/stdio/CMakeLists.txt
+++ b/libc/test/src/stdio/CMakeLists.txt
@@ -159,6 +159,8 @@ add_libc_test(
SRCS
snprintf_test.cpp
DEPENDS
+ libc.hdr.types.wchar_t
+ libc.hdr.wchar_macros
libc.src.stdio.snprintf
)
diff --git a/libc/test/src/stdio/snprintf_test.cpp b/libc/test/src/stdio/snprintf_test.cpp
index 95507e0885dbf..43f44b521a119 100644
--- a/libc/test/src/stdio/snprintf_test.cpp
+++ b/libc/test/src/stdio/snprintf_test.cpp
@@ -6,6 +6,8 @@
//
//===----------------------------------------------------------------------===//
+#include "hdr/types/wchar_t.h"
+#include "hdr/wchar_macros.h"
#include "src/stdio/snprintf.h"
#include "test/UnitTest/ErrnoCheckingTest.h"
@@ -74,3 +76,45 @@ TEST(LlvmLibcSNPrintfTest, CharsWrittenOverflow) {
EXPECT_LT(written, 0);
ASSERT_ERRNO_FAILURE();
}
+
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
+TEST(LlvmLibcSNPrintfTest, WideCharConversion) {
+ char buff[16];
+ int written;
+
+ written = LIBC_NAMESPACE::snprintf(buff, sizeof(buff), "%lc",
+ static_cast<wchar_t>(L'€'));
+ EXPECT_EQ(written, 3);
+ ASSERT_STREQ(buff, "€");
+}
+
+TEST(LlvmLibcSNPrintfTest, WideCharConversionLeftJustified) {
+ char buff[16];
+ int written;
+
+ written = LIBC_NAMESPACE::snprintf(buff, sizeof(buff), "%-4lc",
+ static_cast<wchar_t>(L'€'));
+ EXPECT_EQ(written, 6);
+ ASSERT_STREQ(buff, "€ ");
+}
+
+TEST(LlvmLibcSNPrintfTest, WideCharConversionRightJustified) {
+ char buff[16];
+ int written;
+
+ written = LIBC_NAMESPACE::snprintf(buff, sizeof(buff), "%4lc",
+ static_cast<wchar_t>(L'€'));
+ EXPECT_EQ(written, 6);
+ ASSERT_STREQ(buff, " €");
+}
+
+TEST(LlvmLibcSNPrintfTest, WideCharWEOFConversion) {
+ char buff[16];
+ int written;
+
+ written = LIBC_NAMESPACE::snprintf(buff, sizeof(buff), "%lc",
+ static_cast<wchar_t>(WEOF));
+ EXPECT_EQ(written, -1);
+ ASSERT_ERRNO_FAILURE();
+}
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
\ No newline at end of file
>From 58bb85030f2bc5a5566477d70178a36d64468c5f Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Sat, 6 Dec 2025 18:01:29 -0800
Subject: [PATCH 6/8] fix build errors
---
libc/src/stdio/printf_core/CMakeLists.txt | 3 ++-
libc/src/stdio/printf_core/char_converter.h | 7 ++++---
libc/test/src/stdio/CMakeLists.txt | 1 +
libc/test/src/stdio/snprintf_test.cpp | 2 +-
4 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/libc/src/stdio/printf_core/CMakeLists.txt b/libc/src/stdio/printf_core/CMakeLists.txt
index 6d1866ec755f2..2670355128452 100644
--- a/libc/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/src/stdio/printf_core/CMakeLists.txt
@@ -67,7 +67,7 @@ add_header_library(
parser.h
DEPENDS
.core_structs
- libc.hdr.types.wint_t.h
+ libc.hdr.types.wint_t
libc.src.__support.arg_list
libc.src.__support.ctype_utils
libc.src.__support.str_to_integer
@@ -129,6 +129,7 @@ add_header_library(
libc.src.__support.uint128
libc.src.__support.wchar.mbstate
libc.src.__support.wchar.wcrtomb
+ libc.src.__support.macros.properties.os
libc.src.__support.StringUtil.error_to_string
libc.src.string.memory_utils.inline_memcpy
)
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index 4db6d44d94d7d..e84e894a8bbeb 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -13,6 +13,7 @@
#include "hdr/types/wint_t.h"
#include "hdr/wchar_macros.h"
#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/os.h"
#include "src/__support/wchar/mbstate.h"
#include "src/__support/wchar/wcrtomb.h"
#include "src/stdio/printf_core/converter_utils.h"
@@ -57,11 +58,11 @@ LIBC_INLINE int convert_char(Writer<write_mode> *writer,
RET_IF_RESULT_NEGATIVE(writer->write({mb_str, ret.value()}));
} else {
- #endif // !LIBC_TARGET_OS_IS_WINDOWS
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
RET_IF_RESULT_NEGATIVE(writer->write(c));
- #ifndef LIBC_TARGET_OS_IS_WINDOWS
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
}
- #endif // !LIBC_TARGET_OS_IS_WINDOWS
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
// If the padding is on the right side, write the spaces last.
if (padding_spaces > 0 &&
diff --git a/libc/test/src/stdio/CMakeLists.txt b/libc/test/src/stdio/CMakeLists.txt
index 22d593a682960..adf0a33c2e0ee 100644
--- a/libc/test/src/stdio/CMakeLists.txt
+++ b/libc/test/src/stdio/CMakeLists.txt
@@ -161,6 +161,7 @@ add_libc_test(
DEPENDS
libc.hdr.types.wchar_t
libc.hdr.wchar_macros
+ libc.src.__support.macros.properties.os
libc.src.stdio.snprintf
)
diff --git a/libc/test/src/stdio/snprintf_test.cpp b/libc/test/src/stdio/snprintf_test.cpp
index 43f44b521a119..100eee52c161b 100644
--- a/libc/test/src/stdio/snprintf_test.cpp
+++ b/libc/test/src/stdio/snprintf_test.cpp
@@ -9,7 +9,7 @@
#include "hdr/types/wchar_t.h"
#include "hdr/wchar_macros.h"
#include "src/stdio/snprintf.h"
-
+#include "src/__support/macros/properties/os.h"
#include "test/UnitTest/ErrnoCheckingTest.h"
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
>From 9e356787a2897d924240a1a4451ddc41bf083e02 Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Sat, 6 Dec 2025 19:10:18 -0800
Subject: [PATCH 7/8] fix build error
---
libc/test/src/stdio/snprintf_test.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/test/src/stdio/snprintf_test.cpp b/libc/test/src/stdio/snprintf_test.cpp
index 100eee52c161b..bdc019106edd1 100644
--- a/libc/test/src/stdio/snprintf_test.cpp
+++ b/libc/test/src/stdio/snprintf_test.cpp
@@ -117,4 +117,4 @@ TEST(LlvmLibcSNPrintfTest, WideCharWEOFConversion) {
EXPECT_EQ(written, -1);
ASSERT_ERRNO_FAILURE();
}
-#endif // !LIBC_TARGET_OS_IS_WINDOWS
\ No newline at end of file
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
>From 728f399cfe2097417d536f6fb37233bef3e4c67d Mon Sep 17 00:00:00 2001
From: "shubh at DOE" <shubhp at mbm3a24.local>
Date: Sat, 6 Dec 2025 22:58:26 -0800
Subject: [PATCH 8/8] fix win errors
---
libc/src/stdio/printf_core/char_converter.h | 8 ++++++--
libc/test/src/stdio/snprintf_test.cpp | 4 +++-
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
index e84e894a8bbeb..637a5d871d16a 100644
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -9,13 +9,17 @@
#ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CHAR_CONVERTER_H
#define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CHAR_CONVERTER_H
+#include "src/__support/macros/properties/os.h"
+
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
#include "hdr/types/wchar_t.h"
#include "hdr/types/wint_t.h"
#include "hdr/wchar_macros.h"
-#include "src/__support/macros/config.h"
-#include "src/__support/macros/properties/os.h"
#include "src/__support/wchar/mbstate.h"
#include "src/__support/wchar/wcrtomb.h"
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
+
+#include "src/__support/macros/config.h"
#include "src/stdio/printf_core/converter_utils.h"
#include "src/stdio/printf_core/core_structs.h"
#include "src/stdio/printf_core/writer.h"
diff --git a/libc/test/src/stdio/snprintf_test.cpp b/libc/test/src/stdio/snprintf_test.cpp
index bdc019106edd1..0600dce170525 100644
--- a/libc/test/src/stdio/snprintf_test.cpp
+++ b/libc/test/src/stdio/snprintf_test.cpp
@@ -6,10 +6,12 @@
//
//===----------------------------------------------------------------------===//
+#include "src/__support/macros/properties/os.h"
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
#include "hdr/types/wchar_t.h"
#include "hdr/wchar_macros.h"
+#endif // !LIBC_TARGET_OS_IS_WINDOWS
#include "src/stdio/snprintf.h"
-#include "src/__support/macros/properties/os.h"
#include "test/UnitTest/ErrnoCheckingTest.h"
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
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