Fix #5386: Normalize unary operator expressions #5479
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A unary operator expression `pre.op` where `op` is one of `+`, `-`, `~`, `!`
that has a constant type `ConstantType(v)` but that is not a constant expression
(i.e. `pre` has side-effects) is translated to
{ pre; v }
This avoids the situation where we have a Select node which does not have a symbol.
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Derived from biboudis:fix-#5386. Note: Always do PRs from staging then others can work on them. |
smarter
reviewed
Nov 20, 2018
| if (isIdempotentExpr(tree1)) Literal(value) | ||
| else tree1 match { | ||
| case Select(qual, _) if tree1.tpe.isInstanceOf[ConstantType] => | ||
| // it's a unary operator; Simplify `pre.op` to `{ pre; v }` where `v` is the value of `pre.op` |
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If we lose op before pickling, then it'll be missing from the IDE in go-to-definition/find-all-references
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Also I don't really get what's special about unary operators here ?
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They do not get a symbol. So nothing is lost when doing the transform.
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but why do they not get a symbol ?
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Because constant folding replaces the type with a ConstantType.
Add test showing that user-defined unary operators do not cause a problem, even if they have constant types.
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Nov 21, 2018
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Nov 21, 2018
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A unary operator expression
pre.opwhereopis one of+,-,~,!that has a constant type
ConstantType(v)but that is not a constant expression(i.e.
prehas side-effects) is translated toThis avoids the situation where we have a Select node which does not have a symbol.