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Commit67e77b9

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retronymdwijnand
authored andcommitted
[fport] More accurate outer checks in patterns
Avoids eliding outer checks that matter (run/t11534b.scala) andavoids emitting checks that don't (pos/t11534.scala) which avoidscompiler warnings when the tested class doesn't have an outerfield.The latter stops the annoying unchecked warning that appeared sincea recent refactoring made `TermName` a final class.(cherry picked from commit1115959)
1 parentb74ea55 commit67e77b9

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5 files changed

+239
-18
lines changed

5 files changed

+239
-18
lines changed

‎src/compiler/scala/tools/nsc/transform/patmat/MatchTreeMaking.scala‎

Lines changed: 72 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -369,9 +369,6 @@ trait MatchTreeMaking extends MatchCodeGen with Debugging {
369369
defeqTest(pat:Tree,testedBinder:Symbol)=REF(testedBinder)OBJ_EQ pat
370370

371371
overridedefwithOuterTest(orig:Tree)(testedBinder:Symbol,expectedTp:Type):Tree= {
372-
valexpectedPrefix= expectedTp.prefix
373-
valtestedPrefix= testedBinder.info.prefix
374-
375372
// Check if a type is defined in a static location. Unlike `tp.isStatic` before `flatten`,
376373
// this also includes methods and (possibly nested) objects inside of methods.
377374
defdefinedInStaticLocation(tp:Type):Boolean= {
@@ -383,20 +380,78 @@ trait MatchTreeMaking extends MatchCodeGen with Debugging {
383380
tp.typeSymbol.owner== tp.prefix.typeSymbol&& isStatic(tp.prefix)
384381
}
385382

386-
if ((expectedPrefix eqNoPrefix)
387-
|| expectedTp.typeSymbol.isJava
388-
|| definedInStaticLocation(expectedTp)
389-
|| testedPrefix=:= expectedPrefix) orig
390-
else gen.mkAttributedQualifierIfPossible(expectedPrefix)match {
391-
caseNone=> orig
392-
caseSome(expectedOuterRef)=>
393-
// ExplicitOuter replaces `Select(q, outerSym) OBJ_EQ expectedPrefix`
394-
// by `Select(q, outerAccessor(outerSym.owner)) OBJ_EQ expectedPrefix`
395-
// if there's an outer accessor, otherwise the condition becomes `true`
396-
// TODO: centralize logic whether there's an outer accessor and use here?
397-
valsynthOuterGetter= expectedTp.typeSymbol.newMethod(vpmName.outer, newFlags=SYNTHETIC|ARTIFACT) setInfo expectedPrefix
398-
valouterTest= (Select(codegen._asInstanceOf(testedBinder, expectedTp), synthOuterGetter))OBJ_EQ expectedOuterRef
399-
and(orig, outerTest)
383+
// In `def foo(a: b.B) match { case _: p.P }`
384+
// testedBinder.symbol.info = b.B
385+
// expectedTp = p.P
386+
387+
expectedTpmatch {
388+
case _if expectedTp.typeSymbolDirect.isAliasType=>
389+
withOuterTest(orig)(testedBinder, expectedTp.dealias)
390+
caseRefinedType(Nil, _)=> orig
391+
case rt@RefinedType(parent:: rest, scope)=>
392+
// If the pattern type is refined type, emit outer tests for each component.
393+
withOuterTest(withOuterTest(orig)(testedBinder, parent))(testedBinder, copyRefinedType(rt, rest, scope))
394+
case _=>
395+
valexpectedClass= expectedTp.typeSymbol
396+
assert(!expectedClass.isRefinementClass, orig)
397+
// .typeSymbol dealiases, so look at the prefix of the base type at the dealiased symbol,
398+
// not of expectedTp itself.
399+
valexpectedPrefix= expectedTp.baseType(expectedClass).prefix
400+
401+
// If P is a subclass of B, and b =:= p, b.B
402+
// If <fresh>.P a subtype of <fresh>.B and does b =:= p,
403+
// we can assume that a value inhabiting _#P with b.P conforms to p.P.
404+
//
405+
// It is not sufficient to show that p.P is a subtype of p.B, as this
406+
// would incorrectly elide the outer test in:
407+
//
408+
// class P extends p1.B
409+
// def test(b: p1.B) = b match { case _: p1.P }
410+
// test(new p2.P)
411+
defprefixAligns:Boolean= {
412+
expectedTpmatch {
413+
caseTypeRef(pre, _, _)if!pre.isStable=>// e.g. _: Outer#Inner
414+
false
415+
caseTypeRef(pre, sym, args)=>
416+
valtestedBinderClass= testedBinder.info.typeSymbol
417+
valtestedBinderType= testedBinder.info.baseType(testedBinderClass)
418+
419+
valtestedPrefixIsExpectedTypePrefix= pre=:= testedBinderType.prefix
420+
valtestedPrefixAndExpectedPrefixAreStaticallyIdentical:Boolean= {
421+
valfreshPrefix= prematch {
422+
caseThisType(thissym)=>
423+
ThisType(thissym.cloneSymbol(thissym.owner))
424+
case _=>
425+
valpreSym= pre.termSymbol
426+
valfreshPreSym= preSym.cloneSymbol(preSym.owner).setInfo(preSym.info)
427+
singleType(pre.prefix, freshPreSym)
428+
}
429+
valexpectedTpFromFreshPrefix=TypeRef(freshPrefix, sym, args)
430+
valbaseTypeFromFreshPrefix= expectedTpFromFreshPrefix.baseType(testedBinderClass)
431+
freshPrefix eq baseTypeFromFreshPrefix.prefix
432+
}
433+
testedPrefixAndExpectedPrefixAreStaticallyIdentical&& testedPrefixIsExpectedTypePrefix
434+
case _=>
435+
false
436+
}
437+
}
438+
439+
if ((expectedPrefix eqNoPrefix)
440+
|| expectedTp.typeSymbol.isJava
441+
|| definedInStaticLocation(expectedTp)
442+
|| testedBinder.info<:< expectedTp
443+
|| prefixAligns) orig
444+
else gen.mkAttributedQualifierIfPossible(expectedPrefix)match {
445+
caseNone=> orig
446+
caseSome(expectedOuterRef)=>
447+
// ExplicitOuter replaces `Select(q, outerSym) OBJ_EQ expectedPrefix`
448+
// by `Select(q, outerAccessor(outerSym.owner)) OBJ_EQ expectedPrefix`
449+
// if there's an outer accessor, otherwise the condition becomes `true`
450+
// TODO: centralize logic whether there's an outer accessor and use here?
451+
valsynthOuterGetter= expectedTp.typeSymbol.newMethod(vpmName.outer, newFlags=SYNTHETIC|ARTIFACT) setInfo expectedPrefix
452+
valouterTest= (Select(codegen._asInstanceOf(testedBinder, expectedTp), synthOuterGetter))OBJ_EQ expectedOuterRef
453+
and(orig, outerTest)
454+
}
400455
}
401456
}
402457
}

‎test/files/neg/t7721.check‎

Lines changed: 19 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,24 @@ t7721.scala:49: warning: abstract type pattern B.this.Foo is unchecked since it
2222
t7721.scala:49: warning: abstract type pattern B.this.Bar is unchecked since it is eliminated by erasure
2323
case x: Foo with Bar with Concrete => x.bippy + x.barry + x.dingo + x.conco + x.bongo
2424
^
25+
t7721.scala:13: warning: The outer reference in this type test cannot be checked at run time.
26+
case x: Foo with Concrete => x.bippy + x.conco
27+
^
28+
t7721.scala:17: warning: The outer reference in this type test cannot be checked at run time.
29+
case x: Concrete with Foo => x.bippy + x.conco
30+
^
31+
t7721.scala:21: warning: The outer reference in this type test cannot be checked at run time.
32+
case x: Foo with Bar => x.bippy + x.barry
33+
^
34+
t7721.scala:41: warning: The outer reference in this type test cannot be checked at run time.
35+
case x: Foo with Concrete => x.bippy + x.dingo + x.conco
36+
^
37+
t7721.scala:45: warning: The outer reference in this type test cannot be checked at run time.
38+
case x: Concrete with Foo => x.bippy + x.dingo + x.conco
39+
^
40+
t7721.scala:49: warning: The outer reference in this type test cannot be checked at run time.
41+
case x: Foo with Bar with Concrete => x.bippy + x.barry + x.dingo + x.conco + x.bongo
42+
^
2543
error: No warnings can be incurred under -Werror.
26-
8 warnings
44+
14 warnings
2745
1 error

‎test/files/pos/t11534.scala‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,7 @@
1+
objectTest1 {
2+
valg: scala.tools.nsc.Global=???
3+
importg._
4+
deftest(sym:Symbol)= sym.namematch {
5+
case_:TermName=>
6+
}
7+
}

‎test/files/run/t11534b.scala‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
objectTest {
2+
caseclassO(i:Int) {
3+
classA
4+
classBextendsA {
5+
defbOuter=O.this
6+
}
7+
traitC {
8+
defcOuter=O.this
9+
}
10+
classDextends o2.BwithC
11+
}
12+
valo1=newO(1);
13+
valo2=newO(2);
14+
defpat1(a:Test.o1.C)= amatch {
15+
caseb:Test.o1.B=>
16+
assert(b.bOuter eqTest.o1,
17+
s"expected${o1} as outer of value conforming to pattern `b: Test.o1.B`, but got${b.bOuter}")
18+
case _=>
19+
20+
}
21+
defmain(args:Array[String]):Unit= {
22+
pat1(new o1.D)
23+
}
24+
}

‎test/files/run/t11534c.scala‎

Lines changed: 117 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,117 @@
1+
// scalac: -unchecked
2+
importscala.util.Try
3+
4+
objectTest {
5+
classO(vali:Int) {
6+
classA {
7+
valaOuter= i
8+
}
9+
10+
classB1extendsA {
11+
valb1Outer= i
12+
}
13+
}
14+
classM(i:Int)extendsO(i) {
15+
classB2extends m2.A {
16+
valb2Outer= i
17+
}
18+
19+
defpat1(a:M.this.A)= amatch {
20+
caseb:M.this.B1=>// can elide outer check, (a : m1.A) && (a : O#B1) implies (a : m1.B1)
21+
assertOuter(m1.i, b.b1Outer)
22+
true
23+
case _=>
24+
false
25+
}
26+
defpat2(a: m2.A)= amatch {
27+
caseb:M.this.B2=>// needs runtime outer check
28+
assertOuter(m1.i, b.b2Outer)
29+
true
30+
case _=>
31+
false
32+
}
33+
defpat3(a:M.this.B1)= amatch {
34+
caseb:M.this.A=>// can elide outer check, (a : m1.B1) && (a : O#A) implies (a : m1.B1)
35+
assertOuter(m1.i, b.aOuter)
36+
true
37+
case _=>
38+
false
39+
}
40+
defpat4(a:M.this.B2)= amatch {
41+
caseb: m2.A=>// can elide outer check, (a : m1.B2) implies (a : m2.A)
42+
assertOuter(m2.i, b.aOuter)
43+
true
44+
case _=>
45+
false
46+
}
47+
}
48+
49+
valm1=newM(1);
50+
valm2=newM(2);
51+
52+
defpat1(a: m1.A)= amatch {
53+
caseb: m1.B1=>// can elide outer check, (a : m1.A) && (a : O#B1) implies (a : m1.B1)
54+
assertOuter(m1.i, b.b1Outer)
55+
true
56+
case _=>
57+
false
58+
}
59+
defpat2(a: m2.A)= amatch {
60+
caseb: m1.B2=>// needs runtime outer check
61+
assertOuter(m1.i, b.b2Outer)
62+
true
63+
case _=>
64+
false
65+
}
66+
defpat3(a: m1.B1)= amatch {
67+
caseb: m1.A=>// can elide outer check, (a : m1.B1) && (a : O#A) implies (a : m1.B1)
68+
assertOuter(m1.i, b.aOuter)
69+
true
70+
case _=>
71+
false
72+
}
73+
defpat4(a: m1.B2)= amatch {
74+
caseb: m2.A=>// can elide outer check, (a : m1.B2) implies (a : m2.A)
75+
assertOuter(m2.i, b.aOuter)
76+
true
77+
case _=>
78+
false
79+
}
80+
81+
defpat5(a:M#B2)= amatch {
82+
caseb: m2.A=>// can elide outer check, (a : A#B2) implies (a : m2.A)
83+
assertOuter(m2.i, b.aOuter)
84+
true
85+
case _=>
86+
false
87+
}
88+
defassertOuter(expected:Int,actual:Int):Unit= {
89+
if (expected!= actual)throwWrongOuter(expected, actual)
90+
}
91+
caseclassWrongOuter(expected:Int,actual:Int)extendsRuntimeException(s"expected:$expected, actual:$actual")
92+
93+
defmain(args:Array[String]):Unit= {
94+
assert(pat1(new m1.B1))
95+
assert(m1.pat1(new m1.B1))
96+
assert(Try(pat1((new m2.B1).asInstanceOf[m1.B1])).failed.get==WrongOuter(m1.i, m2.i))
97+
assert(Try(m1.pat1((new m2.B1).asInstanceOf[m1.B1])).failed.get==WrongOuter(m1.i, m2.i))
98+
99+
assert(!pat2(new m2.B2))
100+
assert(!m1.pat2(new m2.B2))
101+
assert(pat2(new m1.B2))
102+
assert(m1.pat2(new m1.B2))
103+
104+
assert(pat3(new m1.B1))
105+
assert(m1.pat3(new m1.B1))
106+
assert(Try(pat3((new m2.B1).asInstanceOf[m1.B1])).failed.get==WrongOuter(m1.i, m2.i))
107+
assert(Try(m1.pat3((new m2.B1).asInstanceOf[m1.B1])).failed.get==WrongOuter(m1.i, m2.i))
108+
109+
assert(pat4(new m1.B2))
110+
assert(m1.pat4(new m1.B2))
111+
assert(pat4((new m2.B2).asInstanceOf[m1.B2]))
112+
assert(m1.pat4((new m2.B2).asInstanceOf[m1.B2]))
113+
114+
assert(pat5(new m1.B2))
115+
assert(pat5(new m2.B2))
116+
}
117+
}

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