Detect macro dependencies within the current run

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -1239,17 +1239,48 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
     assert(level == 0)
     val inlinedFrom = enclosingInlineds.last
     val ctx1 = tastyreflect.MacroExpansion.context(inlinedFrom)
-    val evaluatedSplice = Splicer.splice(body, inlinedFrom.sourcePos, MacroClassLoader.fromContext)(ctx1)
 
-    val inlinedNormailizer = new TreeMap {
-      override def transform(tree: tpd.Tree)(implicit ctx: Context): tpd.Tree = tree match {
-        case Inlined(EmptyTree, Nil, expr) if enclosingInlineds.isEmpty => transform(expr)
-        case _ => super.transform(tree)
+    val dependencies = macroDependencies(body)
+
+    if (dependencies.nonEmpty) {
+      var location = inlinedFrom.symbol
+      if (location.isLocalDummy) location = location.owner
+
+      val msg =
+        em"""Failed to expand macro. This macro depends on an implementation that is defined in the same project and not yet compiled.
+           |In particular ${inlinedFrom.symbol} depends on ${dependencies.map(_.show).mkString(", ")}.
+           |
+           |Moving ${dependencies.map(_.show).mkString(", ")} to a different project would fix this.
+           |""".stripMargin
+      ctx.error(msg, inlinedFrom.sourcePos)
+      EmptyTree
+    } else {
+      val evaluatedSplice = Splicer.splice(body, inlinedFrom.sourcePos, MacroClassLoader.fromContext)(ctx1)
+
+      val inlinedNormailizer = new TreeMap {
+        override def transform(tree: tpd.Tree)(implicit ctx: Context): tpd.Tree = tree match {
+          case Inlined(EmptyTree, Nil, expr) if enclosingInlineds.isEmpty => transform(expr)
+          case _ => super.transform(tree)
+        }
       }
+      val normalizedSplice = inlinedNormailizer.transform(evaluatedSplice)
+      if (normalizedSplice.isEmpty) normalizedSplice
+      else normalizedSplice.withSpan(span)
     }
-    val normalizedSplice = inlinedNormailizer.transform(evaluatedSplice)
-    if (normalizedSplice.isEmpty) normalizedSplice
-    else normalizedSplice.withSpan(span)
+  }
+
+  /** Return the set of symbols that are refered by the tree and defined in the current run */
+  private def macroDependencies(tree: Tree)(implicit ctx: Context) = {
+    new TreeAccumulator[Set[Symbol]] {
+      override def apply(syms: Set[Symbol], tree: tpd.Tree)(implicit ctx: Context): Set[Symbol] = {
+        val newSyms = tree match {
+          case tree: RefTree if tree.symbol.isDefinedInCurrentRun && tree.symbol.owner != ctx.owner =>
+            syms + tree.symbol
+          case _ => syms
+        }
+        foldOver(newSyms, tree)
+      }
+    }.apply(Set.empty, tree)
   }
 }
 

tests/neg-macros/macros-in-same-project-1.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg-macros/macros-in-same-project-1/Bar.scala:2:13 -----------------------------------------------------
+2 |  Foo.myMacro() // error
+  |  ^^^^^^^^^^^^^
+  |Failed to expand macro. This macro depends on an implementation that is defined in the same project and not yet compiled.
+  |In particular method myMacro depends on method aMacroImplementation.
+  |
+  |Moving method aMacroImplementation to a different project would fix this.
+  | This location is in code that was inlined at Bar.scala:2

tests/neg-macros/macros-in-same-project-1/Bar.scala

@@ -0,0 +1,3 @@
+object Bar {
+  Foo.myMacro() // error
+}

tests/neg-macros/macros-in-same-project-1/Foo.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+object Foo {
+
+  inline def myMacro(): Unit = ${ aMacroImplementation }
+
+  def aMacroImplementation given QuoteContext: Expr[Unit] = '{ println("Hello") }
+
+}

tests/neg-macros/macros-in-same-project-2.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg-macros/macros-in-same-project-2/Bar.scala:5:9 ------------------------------------------------------
+5 |  myMacro() // error
+  |  ^^^^^^^^^
+  |Failed to expand macro. This macro depends on an implementation that is defined in the same project and not yet compiled.
+  |In particular method myMacro depends on method aMacroImplementation, object Foo.
+  |
+  |Moving method aMacroImplementation, object Foo to a different project would fix this.
+  | This location is in code that was inlined at Bar.scala:5

tests/neg-macros/macros-in-same-project-2/Bar.scala

@@ -0,0 +1,7 @@
+object Bar {
+
+  inline def myMacro(): Unit = ${ Foo.aMacroImplementation }
+
+  myMacro() // error
+
+}

tests/neg-macros/macros-in-same-project-2/Foo.scala

@@ -0,0 +1,7 @@
+import scala.quoted._
+
+object Foo {
+
+  def aMacroImplementation given QuoteContext: Expr[Unit] = '{ println("Hello") }
+
+}

tests/neg-macros/macros-in-same-project-3.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg-macros/macros-in-same-project-3/Baz.scala:2:13 -----------------------------------------------------
+2 |  Bar.myMacro() // error
+  |  ^^^^^^^^^^^^^
+  |Failed to expand macro. This macro depends on an implementation that is defined in the same project and not yet compiled.
+  |In particular method myMacro depends on method aMacroImplementation.
+  |
+  |Moving method aMacroImplementation to a different project would fix this.
+  | This location is in code that was inlined at Baz.scala:2

tests/neg-macros/macros-in-same-project-3/Bar.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+object Bar {
+
+  inline def myMacro(): Unit = ${ aMacroImplementation }
+
+  def aMacroImplementation given QuoteContext: Expr[Unit] = Foo.hello()
+
+}

tests/neg-macros/macros-in-same-project-3/Baz.scala

@@ -0,0 +1,3 @@
+object Baz {
+  Bar.myMacro() // error
+}

tests/neg-macros/macros-in-same-project-3/Foo.scala

@@ -0,0 +1,7 @@
+import scala.quoted._
+
+object Foo {
+
+  def hello() given QuoteContext: Expr[Unit] = '{ println("Hello") }
+
+}

tests/neg-macros/macros-in-same-project-4.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg-macros/macros-in-same-project-4/Bar.scala:5:13 -----------------------------------------------------
+5 |  Foo.myMacro() // error
+  |  ^^^^^^^^^^^^^
+  |Failed to expand macro. This macro depends on an implementation that is defined in the same project and not yet compiled.
+  |In particular method myMacro depends on method aMacroImplementation.
+  |
+  |Moving method aMacroImplementation to a different project would fix this.
+  | This location is in code that was inlined at Bar.scala:5

tests/neg-macros/macros-in-same-project-4/Bar.scala

@@ -0,0 +1,8 @@
+import scala.quoted._
+
+object Bar {
+
+  Foo.myMacro() // error
+
+  def hello() given QuoteContext: Expr[Unit] = '{ println("Hello") }
+}

tests/neg-macros/macros-in-same-project-4/Foo.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+object Foo {
+
+  inline def myMacro(): Unit = ${ aMacroImplementation }
+
+  def aMacroImplementation given QuoteContext: Expr[Unit] = Bar.hello()
+
+}