[libc-commits] [libc] [libc][annex_k] Add errno_t. (PR #163094)

Muhammad Bassiouni via libc-commits libc-commits at lists.llvm.org
Thu Oct 16 16:01:18 PDT 2025 

https://github.com/bassiounix updated https://github.com/llvm/llvm-project/pull/163094

>From 2a3f07f24c16b4c4c03c054034d3e87d66000f90 Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Sun, 12 Oct 2025 23:58:37 +0300
Subject: [PATCH 1/5] [libc][annex_k] Add Annex K support macros.

---
 libc/include/llvm-libc-macros/CMakeLists.txt  |  6 +++++
 .../include/llvm-libc-macros/annex-k-macros.h | 26 +++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 libc/include/llvm-libc-macros/annex-k-macros.h

diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
index 76c03d913ee12..f41da94e1d726 100644
--- a/libc/include/llvm-libc-macros/CMakeLists.txt
+++ b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -31,6 +31,12 @@ if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
 endif()
 
+add_macro_header(
+  annex_k_macros
+  HDR
+    annex-k-macros.h
+)
+
 add_macro_header(
   assert_macros
   HDR
diff --git a/libc/include/llvm-libc-macros/annex-k-macros.h b/libc/include/llvm-libc-macros/annex-k-macros.h
new file mode 100644
index 0000000000000..c3f845cd77574
--- /dev/null
+++ b/libc/include/llvm-libc-macros/annex-k-macros.h
@@ -0,0 +1,26 @@
+//===-- Definition of macros to be used with Annex K functions ------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_INCLUDE_LLVM_LIBC_MACROS_ANNEX_K_MACROS_H
+#define LLVM_LIBC_INCLUDE_LLVM_LIBC_MACROS_ANNEX_K_MACROS_H
+
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) ||              \
+    (defined(__cplusplus) && __cplusplus >= 201703L)
+
+// TODO(bassiounix): Who should def this macro (clang vs libc)? Where?
+#define __STDC_LIB_EXT1__ 201112L
+
+#if defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ == 1
+
+#define LIBC_HAS_ANNEX_K
+
+#endif // defined(__STDC_WANT_LIB_EXT1__) && __STDC_WANT_LIB_EXT1__ == 1
+
+#endif // (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) ||
+       // (defined(__cplusplus) && __cplusplus >= 201703L)
+#endif // LLVM_LIBC_INCLUDE_LLVM_LIBC_MACROS_ANNEX_K_MACROS_H

>From d215d654f9036ca16aadc969b5785c53e87f9986 Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Sun, 12 Oct 2025 22:18:17 +0300
Subject: [PATCH 2/5] [libc][annex_k] Add errno_t.

---
 libc/hdr/types/CMakeLists.txt               |  9 +++++++++
 libc/hdr/types/errno_t.h                    | 18 ++++++++++++++++++
 libc/include/CMakeLists.txt                 |  1 +
 libc/include/errno.h.def                    |  2 ++
 libc/include/llvm-libc-types/CMakeLists.txt |  2 ++
 libc/include/llvm-libc-types/errno_t.h      | 18 ++++++++++++++++++
 6 files changed, 50 insertions(+)
 create mode 100644 libc/hdr/types/errno_t.h
 create mode 100644 libc/include/llvm-libc-types/errno_t.h

diff --git a/libc/hdr/types/CMakeLists.txt b/libc/hdr/types/CMakeLists.txt
index 225843924c243..8ec2926ee16fc 100644
--- a/libc/hdr/types/CMakeLists.txt
+++ b/libc/hdr/types/CMakeLists.txt
@@ -162,6 +162,15 @@ add_proxy_header_library(
     libc.include.fcntl
 )
 
+add_proxy_header_library(
+  errno_t
+  HDRS
+    errno_t.h
+  FULL_BUILD_DEPENDS
+    libc.include.llvm-libc-types.errno_t
+    libc.include.errno
+)
+
 add_proxy_header_library(
   fenv_t
   HDRS
diff --git a/libc/hdr/types/errno_t.h b/libc/hdr/types/errno_t.h
new file mode 100644
index 0000000000000..91706b05c9155
--- /dev/null
+++ b/libc/hdr/types/errno_t.h
@@ -0,0 +1,18 @@
+//===-- Proxy for errno_t -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_HDR_TYPES_ERRNO_T_H
+#define LLVM_LIBC_HDR_TYPES_ERRNO_T_H
+
+#define LIBC_HAS_ANNEX_K
+
+#include "include/llvm-libc-types/errno_t.h"
+
+#undef LIBC_HAS_ANNEX_K
+
+#endif // LLVM_LIBC_HDR_TYPES_ERRNO_T_H
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index 81360aac984e0..c70d1190e8342 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -302,6 +302,7 @@ add_header_macro(
   DEPENDS
     .llvm-libc-macros.generic_error_number_macros
     .llvm-libc-macros.error_number_macros
+    .llvm-libc-types.errno_t
 )
 
 add_header_macro(
diff --git a/libc/include/errno.h.def b/libc/include/errno.h.def
index aa1f6c9e48444..35341c60e38b2 100644
--- a/libc/include/errno.h.def
+++ b/libc/include/errno.h.def
@@ -33,4 +33,6 @@ __END_C_DECLS
 
 #define errno (*__llvm_libc_errno())
 
+#include "llvm-libc-types/errno_t.h"
+
 #endif // LLVM_LIBC_ERRNO_H
diff --git a/libc/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index 5f506c4d25c9b..cfd0eabc42d5e 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -298,3 +298,5 @@ add_header(EFI_SYSTEM_TABLE
     .EFI_TABLE_HEADER
     .char16_t
 )
+
+add_header(errno_t HDR errno_t.h)
diff --git a/libc/include/llvm-libc-types/errno_t.h b/libc/include/llvm-libc-types/errno_t.h
new file mode 100644
index 0000000000000..f99fe1266ccd1
--- /dev/null
+++ b/libc/include/llvm-libc-types/errno_t.h
@@ -0,0 +1,18 @@
+//===-- Definition of type errno_t ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_INCLUDE_LLVM_LIBC_TYPES_ERRNO_T_H
+#define LLVM_LIBC_INCLUDE_LLVM_LIBC_TYPES_ERRNO_T_H
+
+#ifdef LIBC_HAS_ANNEX_K
+
+typedef int errno_t;
+
+#endif // LIBC_HAS_ANNEX_K
+
+#endif // LLVM_LIBC_INCLUDE_LLVM_LIBC_TYPES_ERRNO_T_H

>From 17c0bbe0c9f8791104f75bce37c29064bc4387b2 Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Tue, 14 Oct 2025 00:44:08 +0300
Subject: [PATCH 3/5] change location of errno_t

---
 libc/include/llvm-libc-types/CMakeLists.txt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libc/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index cfd0eabc42d5e..e8b3ae8c08a90 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -29,6 +29,7 @@ add_header(double_t HDR double_t.h)
 add_header(DIR HDR DIR.h)
 add_header(dev_t HDR dev_t.h)
 add_header(div_t HDR div_t.h)
+add_header(errno_t HDR errno_t.h)
 add_header(ldiv_t HDR ldiv_t.h)
 add_header(lldiv_t HDR lldiv_t.h)
 add_header(FILE HDR FILE.h)
@@ -298,5 +299,3 @@ add_header(EFI_SYSTEM_TABLE
     .EFI_TABLE_HEADER
     .char16_t
 )
-
-add_header(errno_t HDR errno_t.h)

>From f998c2bfca5013cb29043556912436df17850fcd Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Fri, 17 Oct 2025 01:17:20 +0300
Subject: [PATCH 4/5] add clarifying comment about LIBC_HAS_ANNEX_K

---
 libc/include/llvm-libc-types/errno_t.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libc/include/llvm-libc-types/errno_t.h b/libc/include/llvm-libc-types/errno_t.h
index f99fe1266ccd1..a37b5dece2c35 100644
--- a/libc/include/llvm-libc-types/errno_t.h
+++ b/libc/include/llvm-libc-types/errno_t.h
@@ -9,6 +9,9 @@
 #ifndef LLVM_LIBC_INCLUDE_LLVM_LIBC_TYPES_ERRNO_T_H
 #define LLVM_LIBC_INCLUDE_LLVM_LIBC_TYPES_ERRNO_T_H
 
+// LIBC_HAS_ANNEX_K is a necessary check guard here because errno_t is only
+// defined when Annex K is enabled. We use LIBC_HAS_ANNEX_K internally to
+// indicate whether Annex K is enabled or not.
 #ifdef LIBC_HAS_ANNEX_K
 
 typedef int errno_t;

>From d405dd76677d1bae7c85515e9c698a2ff11f5f7d Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Fri, 17 Oct 2025 01:57:02 +0300
Subject: [PATCH 5/5] add errno_t to hdrgen

---
 libc/include/errno.h.def | 2 --
 libc/include/errno.yaml  | 3 ++-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/libc/include/errno.h.def b/libc/include/errno.h.def
index 35341c60e38b2..aa1f6c9e48444 100644
--- a/libc/include/errno.h.def
+++ b/libc/include/errno.h.def
@@ -33,6 +33,4 @@ __END_C_DECLS
 
 #define errno (*__llvm_libc_errno())
 
-#include "llvm-libc-types/errno_t.h"
-
 #endif // LLVM_LIBC_ERRNO_H
diff --git a/libc/include/errno.yaml b/libc/include/errno.yaml
index 188a9fa1211a1..86afd2f03b20c 100644
--- a/libc/include/errno.yaml
+++ b/libc/include/errno.yaml
@@ -5,7 +5,8 @@ standards:
   - Linux
   - POSIX
 macros: []
-types: []
+types:
+  - type_name: errno_t
 enums: []
 objects: []
 functions: []

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