Use simpler desugaring for splices #8660
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nicolasstucki
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liufengyun
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Apr 5, 2020
| @@ -53,7 +53,7 @@ trait QuotesAndSplices { | |||
| ctx.error(em"Quotes require stable QuoteContext, but found non stable $qctx", qctx.sourcePos) | |||
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| val tree1 = | |||
| if ctx.mode.is(Mode.Pattern) && level == 0 then | |||
| if ctx.mode.is(Mode.Pattern) then | |||
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Because if we are in a pattern and we go in the other branch we might generate some non-pattern trees (after some error has been emitted) which leads to crashes later in typer.
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tests/neg/i8052.scala had this issue. With this change, the error message is also more informative.
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If level == 0 is a correct check, it seems better to keep it, and fix crash & error message elsewhere. The reason is that we don't know whether the removal introduces crashes for more ill-formed programs or not.
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The point is that is was not a correct check. The level checks happen later in the Staging phase.
| case Some(qctxRef) => untpd.Apply(untpd.Apply(untpd.ref(defn.InternalQuoted_exprNestedSplice.termRef), qctxRef), expr) | ||
| case _ => untpd.Apply(untpd.ref(defn.InternalQuoted_exprSplice.termRef), expr) | ||
| case Some(qctxRef) => untpd.Apply(untpd.Apply(untpd.ref(defn.InternalQuoted_exprNestedSplice.termRef), qctxRef), tree.expr) | ||
| case _ => untpd.Apply(untpd.ref(defn.InternalQuoted_exprSplice.termRef), tree.expr) |
This allows writing explicitly the context function of a splice. It will make the desugaring simpler to explain as one can write it explicitly. The downside is that each nested context will get a generic "evidence" name which might be visible to the users. Though this is general limitation of context functions that might need a general fix.
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This allows writing explicitly the context function of a splice. It will make the desugaring simpler to explain as one can write it explicitly.
The downside is that each nested context will get a generic "evidence" name which might be visible to the users. Though this is general limitation of context functions that might need a general fix.