diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala index c5ded4e22dbf..932430c3d4e0 100644 --- a/compiler/src/dotty/tools/dotc/typer/Typer.scala +++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala @@ -2436,8 +2436,38 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer val capabilityProof = caughtExceptions.reduce(OrType(_, _, true)) untpd.Block(makeCanThrow(capabilityProof), expr) + /** Graphic explanation of NotNullInfo logic: + * Leftward exit indicates exceptional case + * Downward exit indicates normal case + * + * ┌─────┐ + * │ Try ├─────┬────────┬─────┐ + * └──┬──┘ ▼ ▼ │ + * │ ┌───────┐┌───────┐ │ + * │ │ Catch ││ Catch ├─┤ + * │ └───┬───┘└───┬───┘ │ + * └─┬──────┴────────┘ │ + * ▼ ▼ + * ┌─────────┐ ┌─────────┐ + * │ Finally ├──────┐ │ Finally ├──┐ + * └────┬────┘ │ └────┬────┘ │ + * ▼ └─────────┴───────┴─► + * α = tryEffect + * λ = α.retracted.seq.(catchEffects.reduce.alt) + * β = α.alt(λ) + * finallyCtx = β.retracted + * δ = finallyEffect + * resultNNInfo = β.seq(δ).alt(β.retracted.seq(δ).seq(empty.terminated)) + * + * It is sufficient to type finally once provided that we type it in a context + * that considers all the paths before it that reach the finally. Since the NNinfo + * that we get from typing finally summarizes the effect of the finally, we can + * type the finally once and use the obtained NN info twice: once sequenced + * with β (normalNNInfo) and once sequenced with β.retractedInfo but post-sequenced + * by empty.terminated (to indicate that this path does not reach the code after + * the try-catch-finally). + */ def typedTry(tree: untpd.Try, pt: Type)(using Context): Try = - var nnInfo = NotNullInfo.empty val expr2 :: cases2x = harmonic(harmonize, pt) { // We want to type check tree.expr first to comput NotNullInfo, but `addCanThrowCapabilities` // uses the types of patterns in `tree.cases` to determine the capabilities. @@ -2450,25 +2480,27 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer val casesEmptyBody2 = typedCases(casesEmptyBody1, EmptyTree, defn.ThrowableType, WildcardType) val expr1 = typed(addCanThrowCapabilities(tree.expr, casesEmptyBody2), pt.dropIfProto) - // Since we don't know at which point the the exception is thrown in the body, - // we have to collect any reference that is once retracted. - nnInfo = expr1.notNullInfo.retractedInfo - - val casesCtx = ctx.addNotNullInfo(nnInfo) + val casesCtx = ctx.addNotNullInfo(expr1.notNullInfo.retractedInfo) val cases1 = typedCases(tree.cases, EmptyTree, defn.ThrowableType, pt.dropIfProto)(using casesCtx) expr1 :: cases1 }: @unchecked val cases2 = cases2x.asInstanceOf[List[CaseDef]] - + val exprNNInfo = expr2.notNullInfo // It is possible to have non-exhaustive cases, and some exceptions are thrown and not caught. // Therefore, the code in the finalizer and after the try block can only rely on the retracted // info from the cases' body. - if cases2.nonEmpty then - nnInfo = nnInfo.seq(cases2.map(_.notNullInfo.retractedInfo).reduce(_.alt(_))) - - val finalizer1 = typed(tree.finalizer, defn.UnitType)(using ctx.addNotNullInfo(nnInfo)) - nnInfo = nnInfo.seq(finalizer1.notNullInfo) - assignType(cpy.Try(tree)(expr2, cases2, finalizer1), expr2, cases2).withNotNullInfo(nnInfo) + val casesNNInfo = if cases2.nonEmpty then + exprNNInfo.retractedInfo.seq(cases2.map(_.notNullInfo).reduce(_.alt(_))) + else + NotNullInfo.empty.terminatedInfo + val catchSuccessNNInfo = exprNNInfo.alt(casesNNInfo) + val catchFailNNInfo = catchSuccessNNInfo.retractedInfo + + val finalizer1 = typed(tree.finalizer, defn.UnitType)(using ctx.addNotNullInfo(catchFailNNInfo)) + val normalFinalNNInfo = catchSuccessNNInfo.seq(finalizer1.notNullInfo) + val exceptionalFinalNNInfo = catchFailNNInfo.seq(finalizer1.notNullInfo) + val resNNInfo = normalFinalNNInfo.alt(exceptionalFinalNNInfo.seq(NotNullInfo.empty.terminatedInfo)) + assignType(cpy.Try(tree)(expr2, cases2, finalizer1), expr2, cases2).withNotNullInfo(resNNInfo) def typedTry(tree: untpd.ParsedTry, pt: Type)(using Context): Try = val cases: List[untpd.CaseDef] = tree.handler match diff --git a/tests/explicit-nulls/neg/i21619.scala b/tests/explicit-nulls/neg/i21619.scala index d7af27e3fe64..014bb3639c61 100644 --- a/tests/explicit-nulls/neg/i21619.scala +++ b/tests/explicit-nulls/neg/i21619.scala @@ -13,6 +13,22 @@ def test1: String = x.replace("", "") // error def test2: String = + var x: String | Null = null + x = "" + var i: Int = 1 + try + i match + case _ => + x = null + throw new Exception() + x = "" + catch + case e: NoSuchMethodError => + x = "e" + x.replace("", "") // ok + +// From i24296 +def test2_2: String = var x: String | Null = null x = "" var i: Int = 1 @@ -25,8 +41,43 @@ def test2: String = catch case e: Exception => x = "e" + case _ => x.replace("", "") // error +def test2_3: String = + var x: String | Null = null + x = "" + var i: Int = 1 + try + i match + case _ => + x = null + throw new Exception() + x = "" + catch + case e: NoSuchMethodError => + x = "e" + case e: AbstractMethodError => + x = "e" + x.replace("", "") // ok + +def test2_4: String = + var x: String | Null = null + x = "" + var i: Int = 1 + try + i match + case _ => + x = null + throw new Exception() + x = "" + catch + case e: NoSuchMethodError => + x = "e" + case e: AbstractMethodError => + throw new Exception() + x.replace("", "") // ok + def test3: String = var x: String | Null = null x = "" @@ -89,4 +140,111 @@ def test6 = { } } x.replace("", "") // error -} \ No newline at end of file +} + +// From i24296 +def test7() = + var x: String | Null = null + try { + x = "" + } catch { + case e => + throw e + } + x.trim() // ok + +def test8() = + var x: String | Null = null + try { + try { + x = "" + } catch { + case e => throw e + } + } catch { + case e => throw e + } + x.trim() // ok + +def test9() = + var x: String | Null = null + try { + x = "" + } catch { + case e: AssertionError => + throw e + case _ => + } + x.trim() // error + +def test9_2() = + var x: String | Null = null + try { + x = "" + } catch { + case e: AssertionError => + throw e + } + x.trim() // ok + +def test10() = + var x: String | Null = null + try { + x = "" + } catch { + case e => + throw e + } finally { + x = null + } + x.trim() // error + +def test11() = + var x: String | Null = null + try { + x = "" + } catch { + case e => + x = null + throw e + } finally { + x = "" + } + x.trim() // ok + +def test12() = + var x: String | Null = null + try { + x = "" + } catch { + case e => + x = null + throw e + } finally { + throw new Exception + x = "" + } + x.trim() // ok + +def test12_2() = + var x: String | Null = null + try { + x = "" + } catch { + case e => + x = null + throw e + } finally { + throw new Exception + } + x.trim() // ok + +def test13() = + var x: String | Null = null + try { + x = null + throw new RuntimeException + } finally { + x.trim() // error + } + x.trim() // OK \ No newline at end of file