From 71f9a9fded4be902221ab73437dd6678d2287ef7 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Thu, 24 Aug 2023 16:27:04 +0200
Subject: [PATCH] Fix macro dependency tracking for `this`

The symbols of trees do not have enough information to determine the
full dependencies. For example, if we have an `Ident` we need to look at
its type to figure out which is the `this` prefix on which it is defined.

Fix #18434
---
 .../dotty/tools/dotc/inlines/Inliner.scala    | 20 +++++++++++++------
 tests/pos-macros/i18434/Inline_2.scala        |  8 ++++++++
 tests/pos-macros/i18434/Macro_1.scala         |  7 +++++++
 tests/pos-macros/i18434/Test_2.scala          |  5 +++++
 4 files changed, 34 insertions(+), 6 deletions(-)
 create mode 100644 tests/pos-macros/i18434/Inline_2.scala
 create mode 100644 tests/pos-macros/i18434/Macro_1.scala
 create mode 100644 tests/pos-macros/i18434/Test_2.scala

diff --git a/compiler/src/dotty/tools/dotc/inlines/Inliner.scala b/compiler/src/dotty/tools/dotc/inlines/Inliner.scala
index 8bd89a71fa50..9703332f9e61 100644
--- a/compiler/src/dotty/tools/dotc/inlines/Inliner.scala
+++ b/compiler/src/dotty/tools/dotc/inlines/Inliner.scala
@@ -1065,15 +1065,23 @@ class Inliner(val call: tpd.Tree)(using Context):
    *  This corresponds to the symbols that will need to be interpreted.
    */
   private def macroDependencies(tree: Tree)(using Context) =
+    val typeAccumulator = new TypeAccumulator[List[Symbol]] {
+      def apply(x: List[Symbol], tp: Type): List[Symbol] = tp match
+        case tp: TermRef =>
+          if tp.symbol.isDefinedInCurrentRun then foldOver(tp.symbol :: x, tp)
+          else foldOver(x, tp)
+        case tp: ThisType if tp.typeSymbol.isDefinedInCurrentRun =>
+          foldOver(tp.typeSymbol :: x, tp)
+        case _ =>
+          x
+    }
     new TreeAccumulator[List[Symbol]] {
       override def apply(syms: List[Symbol], tree: tpd.Tree)(using Context): List[Symbol] =
-        tree match {
-          case tree: RefTree if tree.isTerm && level == -1 && tree.symbol.isDefinedInCurrentRun && !tree.symbol.isLocal =>
-            foldOver(tree.symbol :: syms, tree)
-          case _: This if level == -1 && tree.symbol.isDefinedInCurrentRun =>
-            tree.symbol :: syms
+        tree match
+          case tree: RefTree if tree.isTerm && level == -1 && !tree.symbol.isLocal =>
+            typeAccumulator(syms, tree.tpe)
           case _: TypTree => syms
           case _ => foldOver(syms, tree)
-        }
     }.apply(Nil, tree)
+
 end Inliner
diff --git a/tests/pos-macros/i18434/Inline_2.scala b/tests/pos-macros/i18434/Inline_2.scala
new file mode 100644
index 000000000000..6818df6b81e3
--- /dev/null
+++ b/tests/pos-macros/i18434/Inline_2.scala
@@ -0,0 +1,8 @@
+package user
+
+import defn.Macro
+
+object Inline extends Macro {
+  inline def callMacro(): Int =
+    ${ impl() }
+}
diff --git a/tests/pos-macros/i18434/Macro_1.scala b/tests/pos-macros/i18434/Macro_1.scala
new file mode 100644
index 000000000000..fe99162bdf84
--- /dev/null
+++ b/tests/pos-macros/i18434/Macro_1.scala
@@ -0,0 +1,7 @@
+package defn
+
+import scala.quoted.*
+
+abstract class Macro {
+  def impl()(using Quotes): Expr[Int] = '{1}
+}
diff --git a/tests/pos-macros/i18434/Test_2.scala b/tests/pos-macros/i18434/Test_2.scala
new file mode 100644
index 000000000000..666bf5fd379f
--- /dev/null
+++ b/tests/pos-macros/i18434/Test_2.scala
@@ -0,0 +1,5 @@
+package user
+
+object Test {
+  Inline.callMacro()
+}