How Hard Could It Be? Lessons Learned from Replacing int64 With int64_t.
summary
Google spends a year-plus migrating a typedef across ~250M lines to the standard int64_t, first proving the aliases are identical, then fixing ~1,000 template deduction failures, hundreds of format-string sites, virtual-signature mismatches, and dozens of ODR/linker issues. Built a replacement string printf → str format with constexpr-like checking, wrote many clang-tidy fixes (including the static const-expr pattern), used PGO remapping to avoid a measured ~2% web search regression, and lands the migration successfully.
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chapters (9)
- 0:00Introduction to C++ integers
- 1:02The problem with type aliases
- 5:37Strategies for refactoring
- 13:54Handling reference mismatches
- 18:34Overload resolution issues
- 23:46Silent logic errors
- 28:36Format string challenges
- 32:30Linker and definition errors
- 37:55Performance and conclusions
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