Make all items of config-host.h consistent.  To keep the --disable-coroutine-pool
code visible to the compiler, mutuate the IS_ENABLED() macro from Linux.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qemu/compiler.h     | 15 +++++++++++++++
 meson.build                 |  2 +-
 tests/unit/test-coroutine.c |  2 +-
 util/qemu-coroutine.c       |  4 ++--
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 1109482a000..c797f0d4572 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -212,4 +212,19 @@
 # define QEMU_USED
 #endif
 
+/*
+ * Ugly CPP trick that is like "defined FOO", but also works in C
+ * code.  Useful to replace #ifdef with "if" statements; assumes
+ * the symbol was defined with Meson's "config.set()", so it is empty
+ * if defined.
+ */
+#define IS_ENABLED(x)                  IS_EMPTY(x)
+
+#define IS_EMPTY_JUNK_                 junk,
+#define IS_EMPTY(value)                IS_EMPTY_(IS_EMPTY_JUNK_##value)
+
+/* Expands to either SECOND_ARG(junk, 1, 0) or SECOND_ARG(IS_EMPTY_JUNK_CONFIG_FOO 1, 0)  */
+#define SECOND_ARG(first, second, ...) second
+#define IS_EMPTY_(junk_maybecomma)     SECOND_ARG(junk_maybecomma 1, 0)
+
 #endif /* COMPILER_H */
diff --git a/meson.build b/meson.build
index bd65a111aa8..010d2c649c2 100644
--- a/meson.build
+++ b/meson.build
@@ -2194,7 +2194,7 @@ if get_option('debug_stack_usage') and have_coroutine_pool
   message('Disabling coroutine pool to measure stack usage')
   have_coroutine_pool = false
 endif
-config_host_data.set10('CONFIG_COROUTINE_POOL', have_coroutine_pool)
+config_host_data.set('CONFIG_COROUTINE_POOL', have_coroutine_pool)
 config_host_data.set('CONFIG_DEBUG_GRAPH_LOCK', get_option('debug_graph_lock'))
 config_host_data.set('CONFIG_DEBUG_MUTEX', get_option('debug_mutex'))
 config_host_data.set('CONFIG_DEBUG_STACK_USAGE', get_option('debug_stack_usage'))
diff --git a/tests/unit/test-coroutine.c b/tests/unit/test-coroutine.c
index b0d21d673a0..a2563647e74 100644
--- a/tests/unit/test-coroutine.c
+++ b/tests/unit/test-coroutine.c
@@ -645,7 +645,7 @@ int main(int argc, char **argv)
      * with a sentinel value.  If there is no freelist this would legitimately
      * crash, so skip it.
      */
-    if (CONFIG_COROUTINE_POOL) {
+    if (IS_ENABLED(CONFIG_COROUTINE_POOL)) {
         g_test_add_func("/basic/no-dangling-access", test_no_dangling_access);
     }
 
diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
index 17a88f65053..5fd2dbaf8bb 100644
--- a/util/qemu-coroutine.c
+++ b/util/qemu-coroutine.c
@@ -57,7 +57,7 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry, void *opaque)
 {
     Coroutine *co = NULL;
 
-    if (CONFIG_COROUTINE_POOL) {
+    if (IS_ENABLED(CONFIG_COROUTINE_POOL)) {
         CoroutineQSList *alloc_pool = get_ptr_alloc_pool();
 
         co = QSLIST_FIRST(alloc_pool);
@@ -99,7 +99,7 @@ static void coroutine_delete(Coroutine *co)
 {
     co->caller = NULL;
 
-    if (CONFIG_COROUTINE_POOL) {
+    if (IS_ENABLED(CONFIG_COROUTINE_POOL)) {
         if (release_pool_size < qatomic_read(&pool_max_size) * 2) {
             QSLIST_INSERT_HEAD_ATOMIC(&release_pool, co, pool_next);
             qatomic_inc(&release_pool_size);
-- 
2.41.0