Merge bitcoin/bitcoin#25170: build: Enable RPC_DOC_CHECK on --enable-debug

fafae678f6 build: Enable RPC_DOC_CHECK on --enable-debug (MacroFake)

Pull request description:

  This probably makes no large difference, as the setting is already enabled by default in the functional tests. However, I think it is nice to also enable it in debug builds by default to catch issues while manually testing without the runtime flags specified.

  See also https://github.com/bitcoin/bitcoin/issues/24709

ACKs for top commit:
  vincenzopalazzo:
    utACK https://github.com/bitcoin/bitcoin/pull/25170/commits/fafae678f6cd8aaca2be8ece501b258160f7fbfa

Tree-SHA512: cea3276fc9b5a3bc0f6d9819be9a50b19ecf762729d3e3975abdf00da06beaa3f664b18a826fbab1fedd9143bc0624a95a490bfe40c4b5b0a0f94dbc565ce738

configure.ac

@@ -378,6 +378,7 @@ if test "$enable_debug" = "yes"; then
 
   AX_CHECK_PREPROC_FLAG([-DDEBUG], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG"], [], [$CXXFLAG_WERROR])
   AX_CHECK_PREPROC_FLAG([-DDEBUG_LOCKORDER], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG_LOCKORDER"], [], [$CXXFLAG_WERROR])
+  AX_CHECK_PREPROC_FLAG([-DRPC_DOC_CHECK], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DRPC_DOC_CHECK"], [], [$CXXFLAG_WERROR])
   AX_CHECK_PREPROC_FLAG([-DABORT_ON_FAILED_ASSUME], [DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DABORT_ON_FAILED_ASSUME"], [], [$CXXFLAG_WERROR])
   AX_CHECK_COMPILE_FLAG([-ftrapv], [DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -ftrapv"], [], [$CXXFLAG_WERROR])
 fi

src/rpc/util.h

@@ -22,7 +22,13 @@
 #include <variant>
 #include <vector>
 
-static constexpr bool DEFAULT_RPC_DOC_CHECK{false};
+static constexpr bool DEFAULT_RPC_DOC_CHECK{
+#ifdef RPC_DOC_CHECK
+    true
+#else
+    false
+#endif
+};
 
 /**
  * String used to describe UNIX epoch time in documentation, factored out to a