Merge #20255: util: Add Assume() identity function

faa05854f832405231c9198787a4eafe2cd4c5f0 util: Remove probably misleading TODO (MarcoFalke)
fac5efe730ab5b8694920547203deefc5252d294 util: Add Assume() identity function (MarcoFalke)
fa861569dcfff9e72686dc5f30b1faa645b4d54e util: Allow Assert(...) to be used in all contexts (practicalswift)

Pull request description:

  This is needed for #20138. Please refer to the added documentation for motivation.

ACKs for top commit:
  practicalswift:
    cr ACK faa05854f832405231c9198787a4eafe2cd4c5f0
  jnewbery:
    utACK faa05854f832405231c9198787a4eafe2cd4c5f0
  hebasto:
    ACK faa05854f832405231c9198787a4eafe2cd4c5f0, I have reviewed the code and it looks OK, I agree it can be merged.

Tree-SHA512: 72165fbd898b92ab9a79b070993fa1faa86c2e3545b6645e72c652bda295d5107bc298d0482bf3aaf0926fc0c3e6418a445c0e073b08568c44231f547f76a688

1 files changed, 18 insertions, 2 deletions

diff --git a/src/util/check.h b/src/util/check.h
index 9edf394492..e7620d97a0 100644
--- a/src/util/check.h
+++ b/src/util/check.h
@@ -46,7 +46,7 @@ class NonFatalCheckError : public std::runtime_error
 #error "Cannot compile without assertions!"
 #endif
 
-/** Helper for Assert(). TODO remove in C++14 and replace `decltype(get_pure_r_value(val))` with `T` (templated lambda) */
+/** Helper for Assert() */
 template <typename T>
 T get_pure_r_value(T&& val)
 {
@@ -54,6 +54,22 @@ T get_pure_r_value(T&& val)
 }
 
 /** Identity function. Abort if the value compares equal to zero */
-#define Assert(val) [&]() -> decltype(get_pure_r_value(val)) { auto&& check = (val); assert(#val && check); return std::forward<decltype(get_pure_r_value(val))>(check); }()
+#define Assert(val) ([&]() -> decltype(get_pure_r_value(val)) { auto&& check = (val); assert(#val && check); return std::forward<decltype(get_pure_r_value(val))>(check); }())
+
+/**
+ * Assume is the identity function.
+ *
+ * - Should be used to run non-fatal checks. In debug builds it behaves like
+ *   Assert()/assert() to notify developers and testers about non-fatal errors.
+ *   In production it doesn't warn or log anything.
+ * - For fatal errors, use Assert().
+ * - For non-fatal errors in interactive sessions (e.g. RPC or command line
+ *   interfaces), CHECK_NONFATAL() might be more appropriate.
+ */
+#ifdef ABORT_ON_FAILED_ASSUME
+#define Assume(val) Assert(val)
+#else
+#define Assume(val) ((void)(val))
+#endif
 
 #endif // BITCOIN_UTIL_CHECK_H