converting c source c++

how converting graceful infinite (>300k), sincerely mature c codebase c++?

the kind c i have mind separate files roughly analogous modules (i.e. reduction granular customary oo class-based decomposition), controlling middle linkage lieu private functions data, outmost linkage open functions data. tellurian variables used extensively communication between modules. there unequivocally endless formation exam unit available, nonetheless section (i.e. module) turn tests.

i have mind whole strategy:

1. compile all c++'s c subset working.


2. convert modules vast classes, cross-references scoped category name, nonetheless withdrawal functions information stationary members, working.


3. convert vast classes instances suitable constructors initialized cross-references; reinstate stationary member accesses ambiguous accesses appropriate; working.


4. now, proceed digest an ill-factored oo application, section tests where dependencies tractable, spoil removed classes where not; idea here pierce operative way another during any transformation.

obviously, definitely bit work. there any box studies / fight stories out there kind translation? choice strategies? useful advice?

note 1: way compiler, substantially millions programs rest the intrepidity changing, slow rewriting graceful many an option.

note 2: source perceptibly 20 years old, maybe 30% formula shake (lines run-down + total / before sum lines) per year. heavily reliable extended, words. thus, goals boost mantainability.

[for effect question, assume interpretation c++ mandatory, withdrawal c not an option. indicate adding condition weed out "leave c" answers.]