Supress safe initialization warning in Run class #14465
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liufengyun reviewed Feb 13, 2022
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| I've put together an alternative fix here. If we decide that the other fix is good, I will close this PR. |
Due to the `this` pointer being passed to `start.setRun` in a function called during initialization, the initialization checker cannot prove that `this` is fully initialized. We would get the following error: ``` [error] -- Error: /*******/dotty/compiler/src/dotty/tools/dotc/Run.scala:84:17 [error] 84 | start.setRun(this) [error] | ^^^^ [error] |Cannot prove that the value is fully initialized. Only initialized values may be used as arguments. Calling trace: [error] | -> val run = new Run(this, initCtx) { [ ReplCompiler.scala:42 ] [error] | -> class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with ConstraintRunInfo {iler-b[ Run.scala:38 ] [error] | -> private var myCtx = rootContext(using ictx) [ Run.scala:89 ] [error] | -> val rootCtx = super.rootContext.fresh [ ReplCompiler.scala:62 ] ``` The call to `start.setRun` stores the reference to `this` in a store without accessing any of its fields. The instance of `Run` referrred to by `this` will be fully initialized immediately after that function call. Thus, we are able to safely mark `this` as `@unchecked` without worrying about uninitialized members of the `Run` instance being accessed. Review by @liufengyun 
Xavientois force-pushed the fix-setRun-safe-init-warning branch from 413180a to 3138600 Compare 
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Due to the
thispointer being passed tostart.setRunin a function called during initialization, the initialization checker cannot prove thatthisis fully initialized.We would get the following error:
The call to
start.setRunstores the reference tothisin a store without accessing any of its fields. The instance ofRunreferrred to bythiswill be fully initialized immediately after that function call. Thus, we are able to safely markthisas@uncheckedwithout worrying about uninitialized members of theRuninstance being accessed.Review by @liufengyun