ceph/0039-src-common-dout.h.patch

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diff --git a/src/common/dout.h b/src/common/dout.h
index 4cd60efff8fef..db68a042a7f1b 100644
--- a/src/common/dout.h
+++ b/src/common/dout.h
@@ -144,17 +144,24 @@ struct is_dynamic<dynamic_marker_t<T>> : public std::true_type {};
#else
#define dout_impl(cct, sub, v) \
do { \
- const bool should_gather = [&](const auto cctX) { \
- if constexpr (ceph::dout::is_dynamic<decltype(sub)>::value || \
- ceph::dout::is_dynamic<decltype(v)>::value) { \
+ const bool should_gather = [&](const auto cctX, auto sub_, auto v_) { \
+ /* The check is performed on `sub_` and `v_` to leverage the C++'s \
+ * guarantee on _discarding_ one of blocks of `if constexpr`, which \
+ * includes also the checks for ill-formed code (`should_gather<>` \
+ * must not be feed with non-const expresions), BUT ONLY within \
+ * a template (thus the generic lambda) and under the restriction \
+ * it's dependant on a parameter of this template). \
+ * GCC prior to v14 was not enforcing these restrictions. */ \
+ if constexpr (ceph::dout::is_dynamic<decltype(sub_)>::value || \
+ ceph::dout::is_dynamic<decltype(v_)>::value) { \
return cctX->_conf->subsys.should_gather(sub, v); \
} else { \
- /* The parentheses are **essential** because commas in angle \
- * brackets are NOT ignored on macro expansion! A language's \
- * limitation, sorry. */ \
- return (cctX->_conf->subsys.template should_gather<sub, v>()); \
+ constexpr auto sub_helper = static_cast<decltype(sub_)>(sub); \
+ constexpr auto v_helper = static_cast<decltype(v_)>(v); \
+ return cctX->_conf->subsys.template should_gather<sub_helper, \
+ v_helper>(); \
} \
- }(cct); \
+ }(cct, sub, v); \
\
if (should_gather) { \
ceph::logging::MutableEntry _dout_e(v, sub); \