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Brad King authored
Since commit v3.4.0-rc1~321^2~2 (Genex: Store a backtrace, not a pointer to one, 2015-07-08) we treat cmListFileBacktrace instances as lightweight values. This was true at the time only because the backtrace information was kept in the cmState snapshot hierarchy. However, that forced us to accumulate a lot of otherwise short-lived snapshots just to have the backtrace fields available for reference by cmListFileBacktrace instances. Recent refactoring made backtrace instances independent of the snapshot hierarchy to avoid accumulating short-lived snapshots. This came at the cost of making backtrace values heavy again, leading to lots of string coying and slower execution. Fix this by refactoring cmListFileBacktrace to provide value semantics with efficient shared storage underneath. Teach cmMakefile to maintain its call stack using an instance of cmListFileBacktrace. This approach allows the current backtrace to be efficiently ...
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