XcheckMacro types of Block expression and Apply/TypeApply function (#18242)

Also improve the stack trace shown to the user when a macro assertion
fails.

Fixes #18113

Author: nicolasstucki

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -625,9 +625,11 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
     object Apply extends ApplyModule:
       def apply(fun: Term, args: List[Term]): Apply =
+        xCheckMacroAssert(fun.tpe.widen.isInstanceOf[dotc.core.Types.MethodType], "Expected `fun.tpe` to widen into a `MethodType`")
         xCheckMacroValidExprs(args)
         withDefaultPos(tpd.Apply(fun, args))
       def copy(original: Tree)(fun: Term, args: List[Term]): Apply =
+        xCheckMacroAssert(fun.tpe.widen.isInstanceOf[dotc.core.Types.MethodType], "Expected `fun.tpe` to widen into a `MethodType`")
         xCheckMacroValidExprs(args)
         tpd.cpy.Apply(original)(fun, args)
       def unapply(x: Apply): (Term, List[Term]) =
@@ -666,8 +668,10 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
     object TypeApply extends TypeApplyModule:
       def apply(fun: Term, args: List[TypeTree]): TypeApply =
+        xCheckMacroAssert(fun.tpe.widen.isInstanceOf[dotc.core.Types.PolyType], "Expected `fun.tpe` to widen into a `PolyType`")
         withDefaultPos(tpd.TypeApply(fun, args))
       def copy(original: Tree)(fun: Term, args: List[TypeTree]): TypeApply =
+        xCheckMacroAssert(fun.tpe.widen.isInstanceOf[dotc.core.Types.PolyType], "Expected `fun.tpe` to widen into a `PolyType`")
         tpd.cpy.TypeApply(original)(fun, args)
       def unapply(x: TypeApply): (Term, List[TypeTree]) =
         (x.fun, x.args)
@@ -791,7 +795,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
     object Block extends BlockModule:
       def apply(stats: List[Statement], expr: Term): Block =
-        xCheckMacroBlockOwners(withDefaultPos(tpd.Block(stats, expr)))
+        xCheckMacroBlockOwners(withDefaultPos(tpd.Block(stats, xCheckMacroValidExpr(expr))))
       def copy(original: Tree)(stats: List[Statement], expr: Term): Block =
         xCheckMacroBlockOwners(tpd.cpy.Block(original)(stats, expr))
       def unapply(x: Block): (List[Statement], Term) =
@@ -3095,13 +3099,22 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       if xCheckMacro then termOpt.foreach(xCheckMacroValidExpr)
       termOpt
     private def xCheckMacroValidExpr(term: Term): term.type =
-      if xCheckMacro then
-        assert(!term.tpe.widenDealias.isInstanceOf[dotc.core.Types.MethodicType],
+      xCheckMacroAssert(!term.tpe.widenDealias.isInstanceOf[dotc.core.Types.MethodicType],
           "Reference to a method must be eta-expanded before it is used as an expression: " + term.show)
       term
 
     private inline def xCheckMacroAssert(inline cond: Boolean, inline msg: String): Unit =
-      assert(!xCheckMacro || cond, msg)
+      if xCheckMacro && !cond then
+        xCheckMacroAssertFail(msg)
+
+    private def xCheckMacroAssertFail(msg: String): Unit =
+      val error = new AssertionError(msg)
+      if !yDebugMacro then
+        // start stack trace at the place where the user called the reflection method
+        error.setStackTrace(
+          error.getStackTrace
+            .dropWhile(_.getClassName().startsWith("scala.quoted.runtime.impl")))
+      throw error
 
     object Printer extends PrinterModule:
 

tests/neg-macros/i18113.check

@@ -0,0 +1,15 @@
+
+-- Error: tests/neg-macros/i18113/Test_2.scala:7:8 ---------------------------------------------------------------------
+ 7 |  X.test(ref) // error
+   |  ^^^^^^^^^^^
+   |Exception occurred while executing macro expansion.
+   |java.lang.AssertionError: Reference to a method must be eta-expanded before it is used as an expression: x.Main.ref.plus
+   |	at x.X$.testImpl(Macro_1.scala:16)
+   |
+   |--------------------------------------------------------------------------------------------------------------------
+   |Inline stack trace
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |This location contains code that was inlined from Macro_1.scala:11
+11 |   inline def test(ref:IntRef):Int = ${ testImpl('ref) }
+   |                                     ^^^^^^^^^^^^^^^^^^^
+    --------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i18113/Macro_1.scala

@@ -0,0 +1,21 @@
+package x
+
+import scala.quoted.*
+
+class IntRef(var x: Int) {
+   def plus(y:Int): Int = ???
+}
+
+object X {
+
+   inline def test(ref:IntRef):Int = ${ testImpl('ref) }
+
+   def testImpl(ref:Expr[IntRef])(using Quotes):Expr[Int] = {
+     import quotes.reflect.*
+     val fun0 = Select.unique(ref.asTerm,"plus")
+     val fun1 = Block(List(Assign(Select.unique(ref.asTerm,"x"),Literal(IntConstant(1)))),fun0)
+     val r = Apply(fun1,List(Literal(IntConstant(2))))
+     r.asExprOf[Int]
+   }
+
+}

tests/neg-macros/i18113/Test_2.scala

@@ -0,0 +1,9 @@
+package x
+
+object Main {
+
+  val ref = IntRef(0)
+
+  X.test(ref) // error
+
+}

tests/neg-macros/i18113b.check

@@ -0,0 +1,15 @@
+
+-- Error: tests/neg-macros/i18113b/Test_2.scala:7:8 --------------------------------------------------------------------
+ 7 |  X.test(ref) // error
+   |  ^^^^^^^^^^^
+   |  Exception occurred while executing macro expansion.
+   |  java.lang.AssertionError: Expected `fun.tpe` to widen into a `MethodType`
+   |  	at x.X$.testImpl(Macro_1.scala:27)
+   |
+   |--------------------------------------------------------------------------------------------------------------------
+   |Inline stack trace
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |This location contains code that was inlined from Macro_1.scala:12
+12 |   inline def test(ref:IntRef):Int = ${ testImpl('ref) }
+   |                                     ^^^^^^^^^^^^^^^^^^^
+    --------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i18113b/Macro_1.scala

@@ -0,0 +1,31 @@
+package x
+
+import scala.quoted.*
+
+class IntRef(var x: Int) {
+   def plus(y:Int): Int = ???
+}
+
+
+object X {
+
+   inline def test(ref:IntRef):Int = ${ testImpl('ref) }
+
+   def testImpl(ref:Expr[IntRef])(using Quotes):Expr[Int] = {
+     import quotes.reflect.*
+     val fun0 = Select.unique(ref.asTerm,"plus")
+     val mt = MethodType(List("p"))(
+                _ => List(TypeRepr.of[Int]),
+                _ => TypeRepr.of[Int]
+              )
+     val etaExpanded = Lambda(Symbol.spliceOwner, mt, (owner, params) => {
+             Block(
+               List(Assign(Select.unique(ref.asTerm,"x"),Literal(IntConstant(1)))),
+               Apply(fun0,params.map(_.asInstanceOf[Term]))
+             )
+     })
+     val r = Apply(etaExpanded,List(Literal(IntConstant(2))))
+     r.asExprOf[Int]
+   }
+
+}

tests/neg-macros/i18113b/Test_2.scala

@@ -0,0 +1,9 @@
+package x
+
+object Main {
+
+  val ref = IntRef(0)
+
+  X.test(ref) // error
+
+}