1465872 - Remove (replace?) MOZ_DEV_EDITION check, in the MOZ_DIAGNOSTIC_ASSERT definition

Status: NEW

(Core :: General, enhancement, P3)

Description

[Daniel Holbert [:dholbert]]

We'd like to make Firefox DevEdition into a repack of beta (bug 
1459240).  For that to succeed, we can't have any #if/#ifdef MOZ_DEV_EDITION checks in our C++ code.

One such check is for MOZ_DIAGNOSTIC_ASSERT:
========
#if defined(NIGHTLY_BUILD) || defined(MOZ_DEV_EDITION)
#  define MOZ_DIAGNOSTIC_ASSERT MOZ_RELEASE_ASSERT
#  define MOZ_DIAGNOSTIC_ASSERT_ENABLED 1
#else
#  define MOZ_DIAGNOSTIC_ASSERT MOZ_ASSERT
#  ifdef DEBUG
#    define MOZ_DIAGNOSTIC_ASSERT_ENABLED 1
#  endif
#endif
========
https://dxr.mozilla.org/mozilla-central/rev/5866d6685849311f057e7e229b9ace63a2641c29/mfbt/Assertions.h#462-470

In order for MOZ_DIAGNOSTIC_ASSERT to continue working in DevEdition builds, we would need to make its behavior depend on a pref-check (at least in beta builds), I think.

For non-DEBUG non-Nightly case, we'd want...
   MOZ_DIAGNOSTIC_ASSERT(condition, "string");
...to evaluate to:
   if (IsDevEdition()) {
     MOZ_RELEASE_ASSERT(condition, "string");
   }

Or something like that.  That means these asserts wouldn't be entirely free in release builds, but they'd still be pretty cheap if they use AddBoolVarCache for the pref-lookup.  Importantly: if the pref is disabled (in "real" beta biulds), we'd never have to evaluate the possibly-expensive assertion condition, which is one of the main goal of using these macros.

Comment 1

[J.C. Jones [:jcj] (he/they)]

Marking as an enhancement ; please change if relevant! Thanks.