Refactor transformStats impls for consistency #3

retronym · 2015-02-03T05:20:15Z

Uses the same idiom in Flatten and LambdaLift as is established
in Extender and (recently) Delambdafy. This avoids any possibility
of adding a member to a package twice, as used to happen in SI-9097.

Uses the same idiom in `Flatten` and `LambdaLift` as is established in `Extender` and (recently) `Delambdafy`. This avoids any possibility of adding a member to a package twice, as used to happen in SI-9097.

Under `-Ydelambdafy:method`, a public, static accessor method is created to expose the private method containing the body of the lambda. Currently this accessor method has its parameters in the same order structure as those of the lambda body method. What is this order? There are three categories of parameters: 1. lambda parameters 2. captured parameters (added by lambdalift) 3. self parameters (added to lambda bodies that end up in trait impl classes by mixin, and added unconditionally to the static accessor method.) These are currently emitted in order #3, #1, #2. Here are examples of the current behaviour: BEFORE (trait): ``` % cat sandbox/test.scala && scalac-hash v2.11.5 -Ydelambdafy:method sandbox/test.scala && javap -private -classpath . 'Test$class' trait Member; class Capture; trait LambdaParam trait Test { def member: Member def foo { val local = new Capture (arg: LambdaParam) => "" + arg + member + local } } Compiled from "test.scala" public abstract class Test$class { public static void foo(Test); private static final java.lang.String $anonfun$1(Test, LambdaParam, Capture); public static void $init$(Test); public static final java.lang.String accessor$1(Test, LambdaParam, Capture); } ``` BEFORE (class): ``` % cat sandbox/test.scala && scalac-hash v2.11.5 -Ydelambdafy:method sandbox/test.scala && javap -private -classpath . Test trait Member; class Capture; trait LambdaParam abstract class Test { def member: Member def foo { val local = new Capture (arg: LambdaParam) => "" + arg + member + local } } Compiled from "test.scala" public abstract class Test { public abstract Member member(); public void foo(); private final java.lang.String $anonfun$1(LambdaParam, Capture); public Test(); public static final java.lang.String accessor$1(Test, LambdaParam, Capture); } ``` Contrasting the class case with Java: ``` % cat sandbox/Test.java && javac -d . sandbox/Test.java && javap -private -classpath . Test public abstract class Test { public static class Member {}; public static class Capture {}; public static class LambaParam {}; public static interface I { public abstract Object c(LambaParam arg); } public abstract Member member(); public void test() { Capture local = new Capture(); I i1 = (LambaParam arg) -> "" + member() + local; } } Compiled from "Test.java" public abstract class Test { public Test(); public abstract Test$Member member(); public void test(); private java.lang.Object lambda$test$0(Test$Capture, Test$LambaParam); } ``` We can see that in Java 8 lambda parameters come after captures. If we want to use Java's LambdaMetafactory to spin up our anoymous FunctionN subclasses on the fly, our ordering must change. I can see three options for change: 1. Adjust `LambdaLift` to always prepend captured parameters, rather than appending them. I think we could leave `Mixin` as it is, it already prepends the self parameter. This would result a parameter ordering, in terms of the list above: #3, #2, #1. 2. More conservatively, do this just for methods known to hold lambda bodies. This might avoid needlessly breaking code that has come to depend on our binary encoding. 3. Adjust the parameters of the accessor method only. The body of this method can permute params before calling the lambda body method. This commit implements option #2. In also prototyped #1, and found it worked so long as I limited it to non-constructors, to sidestep the need to make corresponding changes elsewhere in the compiler to avoid the crasher shown in the enclosed test case, which was minimized from a bootstrap failure from an earlier a version of this patch. We would need to defer option #1 to 2.12 in any case, as some of these lifted methods are publicied by the optimizer, and we must leave the signatures alone to comply with MiMa. I've included a test that shows this in all in action. However, that is currently disabled, as we don't have a partest category for tests that require Java 8.

The log messages intented to chronicle implicit search were always being filtered out by virtue of the fact that the the tree passed to `printTyping` was already typed, (e.g. with an implicit MethodType.) This commit enabled printing in this case, although it still filters out trees that are deemed unfit for typer tracing, such as `()`. In the context of implicit search, this happens to filter out the noise of: ``` | | | [search #2] start `()`, searching for adaptation to pt=Unit => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled | | | [search #3] start `()`, searching for adaptation to pt=(=> Unit) => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled | | | \-> <error> ``` ... which I think is desirable. The motivation for this fix was to better display the interaction between implicit search and type inference. For instance: ``` class Foo[A, B] class Test { implicit val f: Foo[Int, String] = ??? def t[A, B](a: A)(implicit f: Foo[A, B]) = ??? t(1) } ``` ```` % scalac -Ytyper-debug sandbox/instantiate.scala ... | |-- t(1) BYVALmode-EXPRmode (site: value <local Test> in Test) | | |-- t BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local Test> in Test) | | | [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing | | | \-> (a: A)(implicit f: Foo[A,B])Nothing | | |-- 1 BYVALmode-EXPRmode-POLYmode (site: value <local Test> in Test) | | | \-> Int(1) | | solving for (A: ?A, B: ?B) | | solving for (B: ?B) | | [search #1] start `[A, B](a: A)(implicit f: Foo[A,B])Nothing` inferring type B, searching for adaptation to pt=Foo[Int,B] (silent: value <local Test> in Test) implicits disabled | | [search #1] considering f | | [adapt] f adapted to => Foo[Int,String] based on pt Foo[Int,B] | | [search #1] solve tvars=?B, tvars.constr= >: String <: String | | solving for (B: ?B) | | [search #1] success inferred value of type Foo[Int,=?String] is SearchResult(Test.this.f, TreeTypeSubstituter(List(type B),List(String))) | | |-- [A, B](a: A)(implicit f: Foo[A,B])Nothing BYVALmode-EXPRmode (site: value <local Test> in Test) | | | \-> Nothing | | [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing | | \-> Nothing ```

must replace old trait accessor symbols by mixed in symbols in the infos of the mixed in symbols ``` trait T { val a: String ; val b: a.type } class C extends T { // a, b synthesized, but the a in b's type, a.type, refers to the original symbol, not the clone in C } ``` symbols occurring in types of synthesized members do not get rebound to other synthesized symbols package <empty>scala#4 { abstract <defaultparam/trait> trait N#7352 extends scala#22.AnyRef#2378 { <method> <deferred> <mutable> <accessor> <triedcooking> <sub_synth> def N$_setter_$self_$eq#15011(x$1#15012: <empty>#3.this.N#7352): scala#23.this.Unit#2340; <method> <deferred> <mutable> <accessor> <triedcooking> <sub_synth> def N$_setter_$n_$eq#15013(x$1#15014: N#7352.this.self#7442.type): scala#23.this.Unit#2340; <method> def /*N*/$init$scala#7441(): scala#23.this.Unit#2340 = { () }; <method> <deferred> <stable> <accessor> <triedcooking> <sub_synth> def self#7442: <empty>#3.this.N#7352; N#7352.this.N$_setter_$self_$eq#15011(scala#22.Predef#1729.$qmark$qmark$qmark#6917); <method> <deferred> <stable> <accessor> <sub_synth> def n#7443: N#7352.this.self#7442.type; N#7352.this.N$_setter_$n_$eq#15013(N#7352.this.self#7442) }; abstract class M#7353 extends scala#22.AnyRef#2378 { <method> <triedcooking> def <init>#13465(): <empty>#3.this.M#7353 = { M#7353.super.<init>scala#2719(); () }; <method> <deferred> <stable> <accessor> <triedcooking> def self#13466: <empty>#3.this.N#7352; <method> <deferred> <stable> <accessor> def n#13467: M#7353.this.self#13466.type }; class C#7354 extends M#7353 with <empty>#3.this.N#7352 { <method> <stable> <accessor> <triedcooking> def self#15016: <empty>#3.this.N#7352 = C#7354.this.self #15015; <triedcooking> private[this] val self #15015: <empty>#3.this.N#7352 = _; <method> <stable> <accessor> def n#15018: C#7354.this.self#7442.type = C#7354.this.n #15017; <triedcooking> private[this] val n #15017: C#7354.this.self#7442.type = _; <method> <mutable> <accessor> <triedcooking> def N$_setter_$self_$eq#15019(x$1#15021: <empty>#3.this.N#7352): scala#23.this.Unit#2340 = C#7354.this.self #15015 = x$1#15021; <method> <mutable> <accessor> <triedcooking> def N$_setter_$n_$eq#15022(x$1#15025: C#7354.this.self#7442.type): scala#23.this.Unit#2340 = C#7354.this.n #15017 = x$1#15025; <method> def <init>#14997(): <empty>#3.this.C#7354 = { C#7354.super.<init>#13465(); () } } } [running phase pickler on dependent_rebind.scala] [running phase refchecks on dependent_rebind.scala] test/files/trait-defaults/dependent_rebind.scala:16: error: overriding field n#15049 in trait N#7352 of type C#7354.this.self#15016.type; value n #15017 has incompatible type; found : => C#7354.this.self#7442.type (with underlying type => C#7354.this.self#7442.type) required: => N#7352.this.self#7442.type class C extends M with N ^

the info-transformed of constructors: - traits receive trait-setters for vals - classes receive fields & accessors for mixed in traits Constructors tree transformer - makes trees for decls added during above info transform - adds mixin super calls to the primary constructor ``` trait OneConcreteVal[T] { var x = 1 // : T = ??? def foo = x } trait OneOtherConcreteVal[T] { var y: T = ??? } class C extends OneConcreteVal[Int] with OneOtherConcreteVal[String] ``` we don't have a field -- only a getter -- so, where will we keep non-getter but-field annotations? mixin only deals with lazy accessors/vals do not used referenced to correlate getter/setter it messes with paramaccessor's usage, and we don't really need it make sure to clone info's, so we don't share symbols for method args this manifests itself as an exception in lambdalift, finding proxies Use NEEDS_TREES for all comms between InfoTransform and tree transform yep, need SYNTHESIZE_IMPL_IN_SUBCLASS distinguish accessors that should be mixed into subclass, and those that simply need to be implemented in tree transform, after info transform added the decl commit 4b4932e Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 6 days ago do assignment to trait fields in AddInterfaces regular class vals get assignments during constructors, as before impl classes get accessors + assignments through trait setters in addinterfaces so that constructors acts on them there, and produced the init method in the required spot (the impl class) bootstrapped compiler needs new partest commit baf568d Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 3 weeks ago produce identical bytecode for constant trait val getters I couldn't bring myself to emit the unused fields that we used to emit for constant vals, even though the getters immediately return the constant, and thus the field goes unused. In the next version, there's no need to synthesize impls for these in subclasses -- the getter can be implemented in the interface. commit b9052da Author: Lukas Rytz <lukas.rytz@gmail.com> Date: 3 weeks ago Fix enclosing method attribute for classes nested in trait fields Trait fields are now created as MethodSymbol (no longer TermSymbol). This symbol shows up in the `originalOwner` chain of a class declared within the field initializer. This promoted the field getter to being the enclosing method of the nested class, which it is not (the EnclosingMethod attribute is a source-level property). commit cf845ab Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 3 weeks ago don't suppress field for unit-typed vals it affects the memory model -- even a write of unit to a field is relevant... commit 337a9dd Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 4 weeks ago unit-typed lazy vals should never receive a field this need was unmasked by test/files/run/t7843-jsr223-service.scala, which no longer printed the output expected from the `0 to 10 foreach` Currently failing tests: - test/files/pos/t6780.scala - test/files/neg/anytrait.scala - test/files/neg/delayed-init-ref.scala - test/files/neg/t562.scala - test/files/neg/t6276.scala - test/files/run/delambdafy_uncurry_byname_inline.scala - test/files/run/delambdafy_uncurry_byname_method.scala - test/files/run/delambdafy_uncurry_inline.scala - test/files/run/delambdafy_uncurry_method.scala - test/files/run/inner-obj-auto.scala - test/files/run/lazy-traits.scala - test/files/run/reify_lazyunit.scala - test/files/run/showraw_mods.scala - test/files/run/t3670.scala - test/files/run/t3980.scala - test/files/run/t4047.scala - test/files/run/t6622.scala - test/files/run/t7406.scala - test/files/run/t7843-jsr223-service.scala - test/files/jvm/innerClassAttribute - test/files/specialized/SI-7343.scala - test/files/specialized/constant_lambda.scala - test/files/specialized/spec-early.scala - test/files/specialized/spec-init.scala - test/files/specialized/spec-matrix-new.scala - test/files/specialized/spec-matrix-old.scala - test/files/presentation/scope-completion-3 commit b1b4e5c Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 4 weeks ago wip: lambdalift fix test/files/trait-defaults/lambdalift.scala works, but still some related tests failing (note that we can't use a bootstrapped compiler yet due to binary incompatibility in partest) commit eae7dac Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 4 weeks ago update check now that trait vals can be concrete, use names not letters note the progression in a concrete trait val now being recognized as such ``` -trait T => true -method $init$ => false -value z1 => true -value z2 => true // z2 is actually concrete! ``` commit 6555c74 Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 4 weeks ago bootstraps again by running info transform once per class... not sure how this ever worked, as separate compilation would transform a trait's info multiple times, resulting in double defs... commit 273cb20 Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 6 weeks ago skip presuper vals in new encoding commit 728e71e Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 6 weeks ago incoherent cyclic references between synthesized members must replace old trait accessor symbols by mixed in symbols in the infos of the mixed in symbols ``` trait T { val a: String ; val b: a.type } class C extends T { // a, b synthesized, but the a in b's type, a.type, refers to the original symbol, not the clone in C } ``` symbols occurring in types of synthesized members do not get rebound to other synthesized symbols package <empty>scala#4 { abstract <defaultparam/trait> trait N#7352 extends scala#22.AnyRef#2378 { <method> <deferred> <mutable> <accessor> <triedcooking> <sub_synth> def N$_setter_$self_$eq#15011(x$1#15012: <empty>#3.this.N#7352): scala#23.this.Unit#2340; <method> <deferred> <mutable> <accessor> <triedcooking> <sub_synth> def N$_setter_$n_$eq#15013(x$1#15014: N#7352.this.self#7442.type): scala#23.this.Unit#2340; <method> def /*N*/$init$scala#7441(): scala#23.this.Unit#2340 = { () }; <method> <deferred> <stable> <accessor> <triedcooking> <sub_synth> def self#7442: <empty>#3.this.N#7352; N#7352.this.N$_setter_$self_$eq#15011(scala#22.Predef#1729.$qmark$qmark$qmark#6917); <method> <deferred> <stable> <accessor> <sub_synth> def n#7443: N#7352.this.self#7442.type; N#7352.this.N$_setter_$n_$eq#15013(N#7352.this.self#7442) }; abstract class M#7353 extends scala#22.AnyRef#2378 { <method> <triedcooking> def <init>#13465(): <empty>#3.this.M#7353 = { M#7353.super.<init>scala#2719(); () }; <method> <deferred> <stable> <accessor> <triedcooking> def self#13466: <empty>#3.this.N#7352; <method> <deferred> <stable> <accessor> def n#13467: M#7353.this.self#13466.type }; class C#7354 extends M#7353 with <empty>#3.this.N#7352 { <method> <stable> <accessor> <triedcooking> def self#15016: <empty>#3.this.N#7352 = C#7354.this.self #15015; <triedcooking> private[this] val self #15015: <empty>#3.this.N#7352 = _; <method> <stable> <accessor> def n#15018: C#7354.this.self#7442.type = C#7354.this.n #15017; <triedcooking> private[this] val n #15017: C#7354.this.self#7442.type = _; <method> <mutable> <accessor> <triedcooking> def N$_setter_$self_$eq#15019(x$1#15021: <empty>#3.this.N#7352): scala#23.this.Unit#2340 = C#7354.this.self #15015 = x$1#15021; <method> <mutable> <accessor> <triedcooking> def N$_setter_$n_$eq#15022(x$1#15025: C#7354.this.self#7442.type): scala#23.this.Unit#2340 = C#7354.this.n #15017 = x$1#15025; <method> def <init>#14997(): <empty>#3.this.C#7354 = { C#7354.super.<init>#13465(); () } } } [running phase pickler on dependent_rebind.scala] [running phase refchecks on dependent_rebind.scala] test/files/trait-defaults/dependent_rebind.scala:16: error: overriding field n#15049 in trait N#7352 of type C#7354.this.self#15016.type; value n #15017 has incompatible type; found : => C#7354.this.self#7442.type (with underlying type => C#7354.this.self#7442.type) required: => N#7352.this.self#7442.type class C extends M with N ^ pos/t9111-inliner-workaround revealed need for: - override def transformInfo(sym: Symbol, tp: Type): Type = synthFieldsAndAccessors(tp) + override def transformInfo(sym: Symbol, tp: Type): Type = if (!sym.isJavaDefined) synthFieldsAndAccessors(tp) else tp commit b56ca2f Author: Adriaan Moors <adriaan.moors@typesafe.com> Date: 6 weeks ago static forwarders & private[this] val in trait object Properties extends PropertiesTrait trait PropertiesTrait { // the protected member is not emitted as a static member of -- it works when dropping the access modifier // somehow, the module class member is considered deferred in BForwardersGen protected val propFilename: String = / } // [log jvm] No forwarder for 'getter propFilename' from Properties to 'module class Properties': false || m.isDeferred == true || false || false // the following method is missing compared to scalac // public final class Properties { // public static String propFilename() { // return Properties$.MODULE$.propFilename(); // } trait Chars { private[this] val char2uescapeArray = Array[Char]('\', 'u', 0, 0, 0, 0) } object Chars extends Chars // +++ w/reflect/scala/reflect/internal/Chars$.class // - private final [C scala83014char2uescapeArray constant fold in forwarder for backwards compat constant-typed final val in trait should yield impl method bean{setter,getter} delegates to setter/getter (commit 1655d1b)

Manually tested with: ``` % cat sandbox/test.scala package p { object X { def f(i: Int) = ??? ; def f(s: String) = ??? } object Main { val res = X.f(3.14) } } % qscalac -Ytyper-debug sandbox/test.scala |-- p EXPRmode-POLYmode-QUALmode (site: package <root>) | \-> p.type |-- object X BYVALmode-EXPRmode (site: package p) | |-- super EXPRmode-POLYmode-QUALmode (silent: <init> in X) | | |-- this EXPRmode (silent: <init> in X) | | | \-> p.X.type | | \-> p.X.type | |-- def f BYVALmode-EXPRmode (site: object X) | | |-- $qmark$qmark$qmark EXPRmode (site: method f in X) | | | \-> Nothing | | |-- Int TYPEmode (site: value i in X) | | | \-> Int | | |-- Int TYPEmode (site: value i in X) | | | \-> Int | | \-> [def f] (i: Int)Nothing | |-- def f BYVALmode-EXPRmode (site: object X) | | |-- $qmark$qmark$qmark EXPRmode (site: method f in X) | | | \-> Nothing | | |-- String TYPEmode (site: value s in X) | | | [adapt] String is now a TypeTree(String) | | | \-> String | | |-- String TYPEmode (site: value s in X) | | | [adapt] String is now a TypeTree(String) | | | \-> String | | \-> [def f] (s: String)Nothing | \-> [object X] p.X.type |-- object Main BYVALmode-EXPRmode (site: package p) | |-- X.f(3.14) EXPRmode (site: value res in Main) | | |-- X.f BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value res in Main) | | | |-- X EXPRmode-POLYmode-QUALmode (silent: value res in Main) | | | | \-> p.X.type | | | \-> (s: String)Nothing <and> (i: Int)Nothing | | |-- 3.14 BYVALmode-EXPRmode (silent: value res in Main) | | | \-> Double(3.14) | | [search #1] start `<?>`, searching for adaptation to pt=Double => String (silent: value res in Main) implicits disabled | | [search #2] start `<?>`, searching for adaptation to pt=(=> Double) => String (silent: value res in Main) implicits disabled | | [search #3] start `<?>`, searching for adaptation to pt=Double => Int (silent: value res in Main) implicits disabled | | 1 implicits in companion scope | | [search scala#4] start `<?>`, searching for adaptation to pt=(=> Double) => Int (silent: value res in Main) implicits disabled | | 1 implicits in companion scope | | second try: <error> and 3.14 | | [search scala#5] start `p.X.type`, searching for adaptation to pt=p.X.type => ?{def f(x$1: ? >: Double(3.14)): ?} (silent: value res in Main) implicits disabled | | [search scala#6] start `p.X.type`, searching for adaptation to pt=(=> p.X.type) => ?{def f(x$1: ? >: Double(3.14)): ?} (silent: value res in Main) implicits disabled sandbox/test.scala:4: error: overloaded method value f with alternatives: (s: String)Nothing <and> (i: Int)Nothing cannot be applied to (Double) val res = X.f(3.14) ^ ```

The following commit message is a squash of several commit messages. - This is the 1st commit message: Add position to stub error messages Stub errors happen when we've started the initialization of a symbol but key information of this symbol is missing (the information cannot be found in any entry of the classpath not sources). When this error happens, we better have a good error message with a position to the place where the stub error came from. This commit goes into this direction by adding a `pos` value to `StubSymbol` and filling it in in all the use sites (especifically `UnPickler`). This commit also changes some tests that test stub errors-related issues. Concretely, `t6440` is using special Partest infrastructure and doens't pretty print the position, while `t5148` which uses the conventional infrastructure does. Hence the difference in the changes for both tests. - This is the commit message #2: Add partest infrastructure to test stub errors `StubErrorMessageTest` is the friend I introduce in this commit to help state stub errors. The strategy to test them is easy and builds upon previous concepts: we reuse `StoreReporterDirectTest` and add some methods that will compile the code and simulate a missing classpath entry by removing the class files from the class directory (the folder where Scalac compiles to). This first iteration allow us to programmatically check that stub errors are emitted under certain conditions. - This is the commit message #3: Improve contents of stub error message This commit does three things: * Keep track of completing symbol while unpickling First, it removes the previous `symbolOnCompletion` definition to be more restrictive/clear and use only positions, since only positions are used to report the error (the rest of the information comes from the context of the `UnPickler`). Second, it adds a new variable called `lazyCompletingSymbol` that is responsible for keeping a reference to the symbol that produces the stub error. This symbol will usually (always?) come from the classpath entries and therefore we don't have its position (that's why we keep track of `symbolOnCompletion` as well). This is the one that we have to explicitly use in the stub error message, the culprit so to speak. Aside from these two changes, this commit modifies the existing tests that are affected by the change in the error message, which is more precise now, and adds new tests for stub errors that happen in complex inner cases and in return type of `MethodType`. * Check that order of initialization is correct With the changes introduced previously to keep track of position of symbols coming from source files, we may ask ourselves: is this going to work always? What happens if two symbols the initialization of two symbols is intermingled and the stub error message gets the wrong position? This commit adds a test case and modifications to the test infrastructure to double check empirically that this does not happen. Usually, this interaction in symbol initialization won't happen because the `UnPickler` will lazily load all the buckets necessary for a symbol to be truly initialized, with the pertinent addresses from which this information has to be deserialized. This ensures that this operation is atomic and no other symbol initialization can happen in the meantime. Even though the previous paragraph is the feeling I got from reading the sources, this commit creates a test to double-check it. My attempt to be better safe than sorry. * Improve contents of the stub error message This commit modifies the format of the previous stub error message by being more precise in its formulation. It follows the structured format: ``` s"""|Symbol '${name.nameKind} ${owner.fullName}.$name' is missing from the classpath. |This symbol is required by '${lazyCompletingSymbol.kindString} ${lazyCompletingSymbol.fullName}'. ``` This format has the advantage that is more readable and explicit on what's happening. First, we report what is missing. Then, why it was required. Hopefully, people working on direct dependencies will find the new message friendlier. Having a good test suite to check the previously added code is important. This commit checks that stub errors happen in presence of well-known and widely used Scala features. These include: * Higher kinded types. * Type definitions. * Inheritance and subclasses. * Typeclasses and implicits. - This is the commit message scala#4: Use `lastTreeToTyper` to get better positions The previous strategy to get the last user-defined position for knowing what was the root cause (the trigger) of stub errors relied on instrumenting `def info`. This instrumentation, while easy to implement, is inefficient since we register the positions for symbols that are already completed. However, we cannot do it only for uncompleted symbols (!hasCompleteInfo) because the positions won't be correct anymore -- definitions using stub symbols (val b = new B) are for the compiler completed, but their use throws stub errors. This means that if we initialize symbols between a definition and its use, we'll use their positions instead of the position of `b`. To work around this we use `lastTreeToTyper`. We assume that stub errors will be thrown by Typer at soonest. The benefit of this approach is better error messages. The positions used in them are now as concrete as possible since they point to the exact tree that **uses** a symbol, instead of the one that **defines** it. Have a look at `StubErrorComplexInnerClass` for an example. This commit removes the previous infrastructure and replaces it by the new one. It also removes the fields positions from the subclasses of `StubSymbol`s. - This is the commit message scala#5: Keep track of completing symbols Make sure that cycles don't happen by keeping track of all the symbols that are being completed by `completeInternal`. Stub errors only need the last completing symbols, but the whole stack of symbols may be useful to reporting other error like cyclic initialization issues. I've added this per Jason's suggestion. I've implemented with a list because `remove` in an array buffer is linear. Array was not an option because I would need to resize it myself. I think that even though list is not as efficient memory-wise, it probably doesn't matter since the stack will usually be small. - This is the commit message scala#6: Remove `isPackage` from `newStubSymbol` Remove `isPackage` since in 2.12.x its value is not used.

add readme with links

Refactor transformStats impls for consistency

486f92c

Uses the same idiom in `Flatten` and `LambdaLift` as is established in `Extender` and (recently) `Delambdafy`. This avoids any possibility of adding a member to a package twice, as used to happen in SI-9097.

retronym mentioned this pull request Feb 3, 2015

SI-9097 Remove spurious warning about conflicting filenames scala/scala#4263

Merged

lrytz merged commit 486f92c into lrytz:t9097 Feb 3, 2015

lrytz pushed a commit that referenced this pull request Mar 22, 2018

Merge pull request #3 from tpolecat/badger

8740eec

add readme with links

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Refactor transformStats impls for consistency #3

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Refactor transformStats impls for consistency #3

Refactor transformStats impls for consistency #3

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