From e245b681291cb1234de30faf48a036a49a1000a2 Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Sat, 28 Jul 2012 09:27:06 -0700 Subject: Promote unchecked warnings into being emitted by default. To make that viable, suppression of unchecked warnings is now available on a per-type-argument basis. The @unchecked annotation has hereby been generalized beyond exhaustiveness to mean context-dependent "disable further compiler checking on this entity." Example of new usage: def f(x: Any) = x match { case xs: List[String @unchecked] => xs.head // no warning case xs: List[Int] => xs.head // unchecked warning } It turns out -unchecked has been put to other noisy uses such as the pattern matcher complaining about its budget like a careworn spouse. This actually simplified the path forward: I left -unchecked in place for that and general compatibility, so those warnings can be enabled as before with -unchecked. The erasure warnings I turned into regular warnings, subject to suppression by @unchecked. Review by @odersky. --- .../tools/nsc/settings/StandardScalaSettings.scala | 2 +- .../scala/tools/nsc/transform/ExplicitOuter.scala | 2 +- .../scala/tools/nsc/typechecker/Infer.scala | 23 +++++++----- .../tools/nsc/typechecker/PatternMatching.scala | 2 +- .../scala/tools/nsc/typechecker/Typers.scala | 2 +- src/library/scala/unchecked.scala | 42 +++++++++++----------- src/reflect/scala/reflect/internal/TreeInfo.scala | 3 -- 7 files changed, 38 insertions(+), 38 deletions(-) (limited to 'src') diff --git a/src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala index 0991577829..ee26bb2817 100644 --- a/src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala +++ b/src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala @@ -43,7 +43,7 @@ trait StandardScalaSettings { val target = ChoiceSetting ("-target", "target", "Target platform for object files. All JVM 1.5 targets are deprecated.", List("jvm-1.5", "jvm-1.5-fjbg", "jvm-1.5-asm", "jvm-1.6", "jvm-1.7", "msil"), "jvm-1.6") - val unchecked = BooleanSetting ("-unchecked", "Enable detailed unchecked (erasure) warnings.") + val unchecked = BooleanSetting ("-unchecked", "Enable additional warnings where generated code depends on assumptions.") val uniqid = BooleanSetting ("-uniqid", "Uniquely tag all identifiers in debugging output.") val usejavacp = BooleanSetting ("-usejavacp", "Utilize the java.class.path in classpath resolution.") val verbose = BooleanSetting ("-verbose", "Output messages about what the compiler is doing.") diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala index 1f7c34b8ad..f0979978b0 100644 --- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala +++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala @@ -416,7 +416,7 @@ abstract class ExplicitOuter extends InfoTransform val (checkExhaustive, requireSwitch) = nselector match { case Typed(nselector1, tpt) => - val unchecked = treeInfo.isUncheckedAnnotation(tpt.tpe) + val unchecked = tpt.tpe hasAnnotation UncheckedClass if (unchecked) nselector = nselector1 diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala index e096b75d6d..3be4a46a79 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala @@ -1366,14 +1366,16 @@ trait Infer { else if (param.isContravariant) >:> else =:= ) - val TypeRef(_, sym, args) = arg - - ( isLocalBinding(sym) - || arg.typeSymbol.isTypeParameterOrSkolem - || (sym.name == tpnme.WILDCARD) // avoid spurious warnings on HK types - || check(arg, param.tpe, conforms) - || warn("non-variable type argument " + arg) - ) + (arg hasAnnotation UncheckedClass) || { + val TypeRef(_, sym, args) = arg.withoutAnnotations + + ( isLocalBinding(sym) + || arg.typeSymbol.isTypeParameterOrSkolem + || (sym.name == tpnme.WILDCARD) // avoid spurious warnings on HK types + || check(arg, param.tpe, conforms) + || warn("non-variable type argument " + arg) + ) + } } // Checking if pt (the expected type of the pattern, and the type @@ -1404,8 +1406,11 @@ trait Infer { case _ => def where = ( if (inPattern) "pattern " else "" ) + typeToTest if (check(typeToTest, typeEnsured, =:=)) () + // Note that this is a regular warning, not an uncheckedWarning, + // which is now the province of such notifications as "pattern matcher + // exceeded its analysis budget." else warningMessages foreach (m => - context.unit.uncheckedWarning(tree.pos, s"$m in type $where is unchecked since it is eliminated by erasure")) + context.unit.warning(tree.pos, s"$m in type $where is unchecked since it is eliminated by erasure")) } } diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala index cf5c7265ad..dbb3067bf6 100644 --- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala +++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala @@ -1228,7 +1228,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL if (settings.XnoPatmatAnalysis.value) (true, false) else scrut match { case Typed(_, tpt) => - (treeInfo.isUncheckedAnnotation(tpt.tpe), + (tpt.tpe hasAnnotation UncheckedClass, // matches with two or fewer cases need not apply for switchiness (if-then-else will do) treeInfo.isSwitchAnnotation(tpt.tpe) && casesNoSubstOnly.lengthCompare(2) > 0) case _ => diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index b1c3249e35..87a1923df4 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -3211,7 +3211,7 @@ trait Typers extends Modes with Adaptations with Tags { // we don't create a new Context for a Match, so find the CaseDef, then go out one level and navigate back to the match that has this case // val thisCase = context.nextEnclosing(_.tree.isInstanceOf[CaseDef]) // val unchecked = thisCase.outer.tree.collect{case Match(selector, cases) if cases contains thisCase => selector} match { - // case List(Typed(_, tpt)) if treeInfo.isUncheckedAnnotation(tpt.tpe) => true + // case List(Typed(_, tpt)) if tpt.tpe hasAnnotation UncheckedClass => true // case t => println("outer tree: "+ (t, thisCase, thisCase.outer.tree)); false // } // println("wrapClassTagUnapply"+ (!isPastTyper && infer.containsUnchecked(pt), pt, uncheckedPattern)) diff --git a/src/library/scala/unchecked.scala b/src/library/scala/unchecked.scala index 10d34312cf..5b05792d97 100644 --- a/src/library/scala/unchecked.scala +++ b/src/library/scala/unchecked.scala @@ -6,32 +6,30 @@ ** |/ ** \* */ - - package scala -/** An annotation that gets applied to a selector in a match expression. - * If it is present, exhaustiveness warnings for that expression will be - * suppressed. - * For example, compiling the code: +/** An annotation to designate that the annotated entity + * should not be considered for additional compiler checks. + * Specific applications include annotating the subject of + * a match expression to suppress exhaustiveness warnings, and + * annotating a type argument in a match case to suppress + * unchecked warnings. + * + * Such suppression should be used with caution, without which + * one may encounter [[scala.MatchError]] or [[java.lang.ClassCastException]] + * at runtime. In most cases one can and should address the + * warning instead of suppressing it. + * * {{{ - * object test extends App { - * def f(x: Option[Int]) = x match { - * case Some(y) => y - * } - * f(None) + * object Test extends App { + * // This would normally warn "match is not exhaustive" + * // because `None` is not covered. + * def f(x: Option[String]) = (x: @unchecked) match { case Some(y) => y } + * // This would normally warn "type pattern is unchecked" + * // but here will blindly cast the head element to String. + * def g(xs: Any) = xs match { case x: List[String @unchecked] => x.head } * } - * }}} - * will display the following warning: - * {{{ - * test.scala:2: warning: does not cover case {object None} - * def f(x: Option[int]) = x match { - * ^ - * one warning found - * }}} - * The above message may be suppressed by substituting the expression `x` - * with `(x: @unchecked)`. Then the modified code will compile silently, - * but, in any case, a [[scala.MatchError]] will be raised at runtime. + * }}} * * @since 2.4 */ diff --git a/src/reflect/scala/reflect/internal/TreeInfo.scala b/src/reflect/scala/reflect/internal/TreeInfo.scala index 7ba749ed2c..dc05d221e6 100644 --- a/src/reflect/scala/reflect/internal/TreeInfo.scala +++ b/src/reflect/scala/reflect/internal/TreeInfo.scala @@ -326,9 +326,6 @@ abstract class TreeInfo { case _ => false } - /** a Match(Typed(_, tpt), _) is unchecked if isUncheckedAnnotation(tpt.tpe) */ - def isUncheckedAnnotation(tpe: Type) = tpe hasAnnotation definitions.UncheckedClass - /** a Match(Typed(_, tpt), _) must be translated into a switch if isSwitchAnnotation(tpt.tpe) */ def isSwitchAnnotation(tpe: Type) = tpe hasAnnotation definitions.SwitchClass -- cgit v1.2.3