dispatch: Create alternative implementation with _Generic

.github/workflows/actions.yml

@@ -47,6 +47,39 @@ jobs:
             changed:
               - 'test/**'
 
+  dispatch-selection:
+    name: Dispatch backend selection
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Compile dispatch with gnu99
+        run: >
+          cc -std=gnu99 -Wall -Wextra -Werror -Iinclude
+          -DVSYNC_EXPECT_DISPATCH_BACKEND=VSYNC_DISPATCH_BACKEND_GNU
+          -c test/dispatch/dispatch_backend_probe.c
+          -o /tmp/dispatch_gnu.o
+      - name: Compile dispatch with c11 (_Generic)
+        run: >
+          cc -std=c11 -Wall -Wextra -Werror -Iinclude
+          -DVSYNC_EXPECT_DISPATCH_BACKEND=VSYNC_DISPATCH_BACKEND_C11
+          -c test/dispatch/dispatch_backend_probe.c
+          -o /tmp/dispatch_c11.o
+      - name: Ensure strict c99 dispatch include fails
+        run: |
+          set +e
+          cc -std=c99 -Werror -Iinclude \
+            -DVSYNC_EXPECT_DISPATCH_BACKEND=VSYNC_DISPATCH_BACKEND_DISABLED \
+            -c test/dispatch/dispatch_backend_probe.c \
+            -o /tmp/dispatch_c99.o 2> /tmp/dispatch_c99.log
+          status=$?
+          if [ $status -eq 0 ]; then
+            echo "Expected dispatch include to fail under strict ISO C99"
+            exit 1
+          fi
+          grep -q "requires -std=gnu99 or -std=c11+" /tmp/dispatch_c99.log
+
   test-install:
     strategy:
       matrix:

CMakeLists.txt

@@ -8,9 +8,11 @@ project(
     VERSION 2.3.1
     DESCRIPTION "VSync atomics")
 
+set(CMAKE_EXPORT_COMMANDS ON)
 set(CMAKE_C_STANDARD 99)
 set(CMAKE_C_STANDARD_REQUIRED ON)
-set(CMAKE_C_EXTENSIONS OFF)
+# Dispatch macros require GNU extensions when building as C99.
+set(CMAKE_C_EXTENSIONS ON)
 
 include(GNUInstallDirs)
 include(CheckSymbolExists)

include/vsync/atomic.hpp

@@ -7,7 +7,8 @@
 
 #include <cassert>
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/await.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_bool.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_BOOL_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_ptr.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_PTR_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_s16.hpp

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: MIT
  */
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_s32.hpp

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: MIT
  */
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_s64.hpp

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: MIT
  */
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_s8.hpp

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: MIT
  */
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_sz.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_SZ_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_u16.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_U16_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_u32.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_U32_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_u64.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_U64_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/core_u8.hpp

@@ -6,7 +6,7 @@
 #define VATOMIC_CORE_U8_HPP
 /*!!!Warning: File generated by tmplr; DO NOT EDIT.!!!*/
 extern "C" {
-#include <vsync/atomic.h>
+#include <vsync/atomic/core.h>
 }
 namespace vsync
 {

include/vsync/atomic/dispatch.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) Huawei Technologies Co., Ltd. 2022-2024. All rights reserved.
+ * Copyright (C) Huawei Technologies Co., Ltd. 2022-2025. All rights reserved.
  * SPDX-License-Identifier: MIT
  */
 
@@ -48,7 +48,7 @@
  * @return current value
  * @memord seq_cst
  */
-#define vatomic_read(a) V_DISPATCH(ALL_RET, read, mo_seq, a)
+#define vatomic_read(a) V_DISPATCH_CONST(ALL_RET, read, mo_seq, a)
 /**
  * @def vatomic_read_acq(a)
  * @brief Dispatches read calls with acquire memory order.
@@ -59,7 +59,7 @@
  * @return current value
  * @memord acquire
  */
-#define vatomic_read_acq(a) V_DISPATCH(ALL_RET, read, mo_acq, a)
+#define vatomic_read_acq(a) V_DISPATCH_CONST(ALL_RET, read, mo_acq, a)
 /**
  * @def vatomic_read_rlx(a)
  * @brief Dispatches read calls with relaxed memory order.
@@ -70,7 +70,7 @@
  * @return current value
  * @memord relaxed
  */
-#define vatomic_read_rlx(a) V_DISPATCH(ALL_RET, read, mo_rlx, a)
+#define vatomic_read_rlx(a) V_DISPATCH_CONST(ALL_RET, read, mo_rlx, a)
 
 /**
  * @def vatomic_write(a, v)
@@ -1250,7 +1250,8 @@
  * @return previously read value
  * @memord seq_cst
  */
-#define vatomic_await_eq(a, c) V_DISPATCH32(ALL_RET, await_eq, mo_seq, a, c)
+#define vatomic_await_eq(a, c)                                                 \
+    V_DISPATCH32_CONST(ALL_RET, await_eq, mo_seq, a, c)
 /**
  * @def vatomic_await_eq_acq(a, c)
  * @brief Dispatches await_eq calls with acquire memory order.
@@ -1262,7 +1263,8 @@
  * @return previously read value
  * @memord acquire
  */
-#define vatomic_await_eq_acq(a, c) V_DISPATCH32(ALL_RET, await_eq, mo_acq, a, c)
+#define vatomic_await_eq_acq(a, c)                                             \
+    V_DISPATCH32_CONST(ALL_RET, await_eq, mo_acq, a, c)
 /**
  * @def vatomic_await_eq_rlx(a, c)
  * @brief Dispatches await_eq calls with relaxed memory order.
@@ -1274,7 +1276,8 @@
  * @return previously read value
  * @memord relaxed
  */
-#define vatomic_await_eq_rlx(a, c) V_DISPATCH32(ALL_RET, await_eq, mo_rlx, a, c)
+#define vatomic_await_eq_rlx(a, c)                                             \
+    V_DISPATCH32_CONST(ALL_RET, await_eq, mo_rlx, a, c)
 /**
  * @def vatomic_await_neq(a, c)
  * @brief Dispatches await_neq calls with seq_cst memory order.
@@ -1286,7 +1289,8 @@
  * @return value satisfying condition
  * @memord seq_cst
  */
-#define vatomic_await_neq(a, c) V_DISPATCH32(ALL_RET, await_neq, mo_seq, a, c)
+#define vatomic_await_neq(a, c)                                                \
+    V_DISPATCH32_CONST(ALL_RET, await_neq, mo_seq, a, c)
 /**
  * @def vatomic_await_neq_acq(a, c)
  * @brief Dispatches await_neq calls with acquire memory order.
@@ -1299,7 +1303,7 @@
  * @memord acquire
  */
 #define vatomic_await_neq_acq(a, c)                                            \
-    V_DISPATCH32(ALL_RET, await_neq, mo_acq, a, c)
+    V_DISPATCH32_CONST(ALL_RET, await_neq, mo_acq, a, c)
 /**
  * @def vatomic_await_neq_rlx(a, c)
  * @brief Dispatches await_neq calls with relaxed memory order.
@@ -1312,7 +1316,7 @@
  * @memord relaxed
  */
 #define vatomic_await_neq_rlx(a, c)                                            \
-    V_DISPATCH32(ALL_RET, await_neq, mo_rlx, a, c)
+    V_DISPATCH32_CONST(ALL_RET, await_neq, mo_rlx, a, c)
 /**
  * @def vatomic_await_le(a, c)
  * @brief Dispatches await_le calls with seq_cst memory order.
@@ -1324,7 +1328,8 @@
  * @return value satisfying condition
  * @memord seq_cst
  */
-#define vatomic_await_le(a, c) V_DISPATCH32(INT_RET, await_le, mo_seq, a, c)
+#define vatomic_await_le(a, c)                                                 \
+    V_DISPATCH32_CONST(INT_RET, await_le, mo_seq, a, c)
 /**
  * @def vatomic_await_le_acq(a, c)
  * @brief Dispatches await_le calls with acquire memory order.
@@ -1336,7 +1341,8 @@
  * @return value satisfying condition
  * @memord acquire
  */
-#define vatomic_await_le_acq(a, c) V_DISPATCH32(INT_RET, await_le, mo_acq, a, c)
+#define vatomic_await_le_acq(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_le, mo_acq, a, c)
 /**
  * @def vatomic_await_le_rlx(a, c)
  * @brief Dispatches await_le calls with relaxed memory order.
@@ -1348,7 +1354,8 @@
  * @return value satisfying condition
  * @memord relaxed
  */
-#define vatomic_await_le_rlx(a, c) V_DISPATCH32(INT_RET, await_le, mo_rlx, a, c)
+#define vatomic_await_le_rlx(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_le, mo_rlx, a, c)
 /**
  * @def vatomic_await_lt(a, c)
  * @brief Dispatches await_lt calls with seq_cst memory order.
@@ -1360,7 +1367,8 @@
  * @return value satisfying condition
  * @memord seq_cst
  */
-#define vatomic_await_lt(a, c) V_DISPATCH32(INT_RET, await_lt, mo_seq, a, c)
+#define vatomic_await_lt(a, c)                                                 \
+    V_DISPATCH32_CONST(INT_RET, await_lt, mo_seq, a, c)
 /**
  * @def vatomic_await_lt_acq(a, c)
  * @brief Dispatches await_lt calls with acquire memory order.
@@ -1372,7 +1380,8 @@
  * @return value satisfying condition
  * @memord acquire
  */
-#define vatomic_await_lt_acq(a, c) V_DISPATCH32(INT_RET, await_lt, mo_acq, a, c)
+#define vatomic_await_lt_acq(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_lt, mo_acq, a, c)
 /**
  * @def vatomic_await_lt_rlx(a, c)
  * @brief Dispatches await_lt calls with relaxed memory order.
@@ -1384,7 +1393,8 @@
  * @return value satisfying condition
  * @memord relaxed
  */
-#define vatomic_await_lt_rlx(a, c) V_DISPATCH32(INT_RET, await_lt, mo_rlx, a, c)
+#define vatomic_await_lt_rlx(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_lt, mo_rlx, a, c)
 /**
  * @def vatomic_await_gt(a, c)
  * @brief Dispatches await_gt calls with seq_cst memory order.
@@ -1396,7 +1406,8 @@
  * @return value satisfying condition
  * @memord seq_cst
  */
-#define vatomic_await_gt(a, c) V_DISPATCH32(INT_RET, await_gt, mo_seq, a, c)
+#define vatomic_await_gt(a, c)                                                 \
+    V_DISPATCH32_CONST(INT_RET, await_gt, mo_seq, a, c)
 /**
  * @def vatomic_await_gt_acq(a, c)
  * @brief Dispatches await_gt calls with acquire memory order.
@@ -1408,7 +1419,8 @@
  * @return value satisfying condition
  * @memord acquire
  */
-#define vatomic_await_gt_acq(a, c) V_DISPATCH32(INT_RET, await_gt, mo_acq, a, c)
+#define vatomic_await_gt_acq(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_gt, mo_acq, a, c)
 /**
  * @def vatomic_await_gt_rlx(a, c)
  * @brief Dispatches await_gt calls with relaxed memory order.
@@ -1420,7 +1432,8 @@
  * @return value satisfying condition
  * @memord relaxed
  */
-#define vatomic_await_gt_rlx(a, c) V_DISPATCH32(INT_RET, await_gt, mo_rlx, a, c)
+#define vatomic_await_gt_rlx(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_gt, mo_rlx, a, c)
 /**
  * @def vatomic_await_ge(a, c)
  * @brief Dispatches await_ge calls with seq_cst memory order.
@@ -1432,7 +1445,8 @@
  * @return value satisfying condition
  * @memord seq_cst
  */
-#define vatomic_await_ge(a, c) V_DISPATCH32(INT_RET, await_ge, mo_seq, a, c)
+#define vatomic_await_ge(a, c)                                                 \
+    V_DISPATCH32_CONST(INT_RET, await_ge, mo_seq, a, c)
 /**
  * @def vatomic_await_ge_acq(a, c)
  * @brief Dispatches await_ge calls with acquire memory order.
@@ -1444,7 +1458,8 @@
  * @return value satisfying condition
  * @memord acquire
  */
-#define vatomic_await_ge_acq(a, c) V_DISPATCH32(INT_RET, await_ge, mo_acq, a, c)
+#define vatomic_await_ge_acq(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_ge, mo_acq, a, c)
 /**
  * @def vatomic_await_ge_rlx(a, c)
  * @brief Dispatches await_ge calls with relaxed memory order.
@@ -1456,7 +1471,8 @@
  * @return value satisfying condition
  * @memord relaxed
  */
-#define vatomic_await_ge_rlx(a, c) V_DISPATCH32(INT_RET, await_ge, mo_rlx, a, c)
+#define vatomic_await_ge_rlx(a, c)                                             \
+    V_DISPATCH32_CONST(INT_RET, await_ge, mo_rlx, a, c)
 
 /**
  * @def vatomic_await_eq_set(a, c, v)