https://issues.dlang.org/show_bug.cgi?id=21593
Issue ID: 21593
Summary: Only update file time if file to be written already
exists
Product: D
Version: D2
Hardware: All
OS: All
Status: NEW
Severity: enhancement
Priority: P1
Component: dmd
Assignee: [email protected]
Reporter: [email protected]
This is a suggestion from Andrei.
Because file writes are so much slower than reads, and because of weak
dependency management in build systems, the compiler will often generate the
same files again and again. This changes file writes to first see if the file
already exists and is identical. If so, it just updates the last written time
on that file instead of writing a new one.
We discussed whether to "touch" the file or not, and decided if it wasn't
touched, it would likely break many build systems.
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