tasty-reflect: Inspecting type tree fails when a macro is called inside a block or a non-type ascripted method

[neko-kai]

To reproduce execute:

git clone https://github.com/zio/izumi-reflect.git
cd izumi-reflect
git checkout feature/dotty-macro-expansion-fails-when-not-inside-type-ascripted-method
sbt '++0.24.0-bin-20200420-c560211-NIGHTLY test:compile'

Output

[error] 26 |      val bazTag = LTT[Baz]
[error]    |                   ^^^^^^^^
[error]    |Exception occurred while executing macro expansion.
[error]    |scala.NotImplementedError: an implementation is missing
[error]    |	at scala.Predef$.$qmark$qmark$qmark(Predef.scala:347)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:120)
[error]    |	at izumi.reflect.dottyreflection.Inspector.prefixOf(Inspector.scala:132)
[error]    |	at izumi.reflect.dottyreflection.Inspector.asNameRefSym(Inspector.scala:219)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:113)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:107)
[error]    |	at izumi.reflect.dottyreflection.Inspector.buildTypeRef(Inspector.scala:33)
[error]    |	at izumi.reflect.dottyreflection.TypeInspections$.apply(TypeInspections.scala:10)
[error]    |	at izumi.reflect.dottyreflection.Inspect$.inspectAny(Inspect.scala:21)
[error]    |
[error]    | This location contains code that was inlined from CurrentDottySupportExtentTest.scala:26
[error]    | This location contains code that was inlined from package.scala:73
[error] -- Error: /private/tmp/izumi-reflect/izumi-reflect/izumi-reflect/src/test/scala/izumi/reflect/test/CurrentDottySupportExtentTest.scala:27:23
[error] 27 |      val bazTag2 = LTT[Baz]
[error]    |                    ^^^^^^^^
[error]    |Exception occurred while executing macro expansion.
[error]    |scala.NotImplementedError: an implementation is missing
[error]    |	at scala.Predef$.$qmark$qmark$qmark(Predef.scala:347)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:120)
[error]    |	at izumi.reflect.dottyreflection.Inspector.prefixOf(Inspector.scala:132)
[error]    |	at izumi.reflect.dottyreflection.Inspector.asNameRefSym(Inspector.scala:219)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:113)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:107)
[error]    |	at izumi.reflect.dottyreflection.Inspector.buildTypeRef(Inspector.scala:33)
[error]    |	at izumi.reflect.dottyreflection.TypeInspections$.apply(TypeInspections.scala:10)
[error]    |	at izumi.reflect.dottyreflection.Inspect$.inspectAny(Inspect.scala:21)
[error]    |
[error]    | This location contains code that was inlined from CurrentDottySupportExtentTest.scala:27
[error]    | This location contains code that was inlined from package.scala:73
[error] -- Error: /private/tmp/izumi-reflect/izumi-reflect/izumi-reflect/src/test/scala/izumi/reflect/test/CurrentDottySupportExtentTest.scala:29:23
[error] 29 |      val barXTag = LTT[Bar[X]]
[error]    |                    ^^^^^^^^^^^
[error]    |Exception occurred while executing macro expansion.
[error]    |scala.NotImplementedError: an implementation is missing
[error]    |	at scala.Predef$.$qmark$qmark$qmark(Predef.scala:347)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:120)
[error]    |	at izumi.reflect.dottyreflection.Inspector.prefixOf(Inspector.scala:132)
[error]    |	at izumi.reflect.dottyreflection.Inspector.asNameRefSym(Inspector.scala:219)
[error]    |	at izumi.reflect.dottyreflection.Inspector.asNameRef(Inspector.scala:212)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:66)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:105)
[error]    |	at izumi.reflect.dottyreflection.Inspector.buildTypeRef(Inspector.scala:33)
[error]    |	at izumi.reflect.dottyreflection.TypeInspections$.apply(TypeInspections.scala:10)
[error]    |	at izumi.reflect.dottyreflection.Inspect$.inspectAny(Inspect.scala:21)
[error]    |
[error]    | This location contains code that was inlined from CurrentDottySupportExtentTest.scala:29
[error]    | This location contains code that was inlined from package.scala:73

Expectation

Compilation succeeds if the commented out wrappng method def test(): Unit = { ... } is uncommented.

That is, the content of the quoted.Type[_] value depends directly on whether or not the LTT inline method is called inside a def test or inside the class body, even though the types referred to are defined inside the current block in both situations. Moreover if the inline calls are placed inside a method, but without a type ascription, def test() = { ... }, the result is the same error.

/cc @nicolasstucki

[odersky]

Can you try to minimize this into a self contained example? We will treat these with priority.

[neko-kai]

@odersky I'll try, but I probably wouldn't have enough time until next week. As it is, the macro codebase of that project is fairly small, but yes, it's not an isolated snippet and may be not ideal for debugging.

[nicolasstucki]

@neko-kai what tree do you get in Inspector.scala#L118? I notice that you don't match ValDef.

[neko-kai]

@nicolasstucki
I've pushed a commit adding debug messages to exceptions in that branch. The tree is a ValDef - but that's not supposed to be there, we're recursing over symbol.tree to collect information about the inheritance hierarchy, so we need the tree to always be the definition tree, unless there's some other way to traverse the type hierarchy.

Error:(26, 23) Exception occurred while executing macro expansion.
java.lang.RuntimeException: SYMBOL TREE, UNSUPPORTED: class dotty.tools.dotc.ast.Trees$ValDef - ValDef(<local CurrentDottySupportExtentTest>,TypeTree[NoType],EmptyTree)
	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:120)
	at izumi.reflect.dottyreflection.Inspector.prefixOf(Inspector.scala:132)
	at izumi.reflect.dottyreflection.Inspector.asNameRefSym(Inspector.scala:217)
	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:113)
	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:107)
	at izumi.reflect.dottyreflection.Inspector.buildTypeRef(Inspector.scala:33)
	at izumi.reflect.dottyreflection.TypeInspections$.apply(TypeInspections.scala:10)
	at izumi.reflect.dottyreflection.Inspect$.inspectAny(Inspect.scala:21)
      val bazTag = LTT[Baz]

Note, if I add code to recurse on the ValDef#tpt it arrives nowhere anyway:

Error:(26, 23) Exception occurred while executing macro expansion.
java.lang.RuntimeException: TTYPE, UNSUPPORTED: class dotty.tools.dotc.core.Types$NoType$ - NoType
	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:94)
	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:105)
	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:119)
	at izumi.reflect.dottyreflection.Inspector.prefixOf(Inspector.scala:134)
	at izumi.reflect.dottyreflection.Inspector.asNameRefSym(Inspector.scala:219)
	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:113)
	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:107)
	at izumi.reflect.dottyreflection.Inspector.buildTypeRef(Inspector.scala:33)
	at izumi.reflect.dottyreflection.TypeInspections$.apply(TypeInspections.scala:10)
	at izumi.reflect.dottyreflection.Inspect$.inspectAny(Inspect.scala:21)
      val bazTag = LTT[Baz]

[neko-kai]

Also, in the macro expansion for LTT[List[Int]], below LTT[Baz] aboe, a Types.LazyRef occurs, which seems like is a very low-level type that doesn't have any methods in tasty-reflect, specifically there's no way to call .underlying and dereference it:

[error] 52 |      val listIntTag0 = LTT[List[Int]]
[error]    |                        ^^^^^^^^^^^^^^
[error]    |Exception occurred while executing macro expansion.
[error]    |java.lang.RuntimeException: TTYPE, UNSUPPORTED: class dotty.tools.dotc.core.Types$LazyRef - LazyRef(...)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:94)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectToB(Inspector.scala:154)
[error]    |	at izumi.reflect.dottyreflection.Inspector.$anonfun$3(Inspector.scala:64)
[error]    |	at scala.collection.immutable.List.map(List.scala:223)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:64)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:71)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:90)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTree(Inspector.scala:105)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectSymbol(Inspector.scala:115)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectTType(Inspector.scala:87)
[error]    |	at izumi.reflect.dottyreflection.Inspector.inspectToB(Inspector.scala:154)
[error]    |	at izumi.reflect.dottyreflection.Inspector.$anonfun$3(Inspector.scala:64)
[error]    |	at scala.collection.immutable.List.map(List.scala:223)