From d0b02b72f833bc83cf6f598897c8fe3f4ba1e1f2 Mon Sep 17 00:00:00 2001
From: Guillaume Martres <smarter@ubuntu.com>
Date: Thu, 26 Sep 2024 16:14:47 +0200
Subject: [PATCH] Handle suspension due to macro call completed in arbitrary
 phases

Previously we only supported suspension in Typer and Inliner. In the added test
case this happens in PostTyper, but I've seen it happen in Mixin too.

Fixes #18517.
---
 compiler/src/dotty/tools/dotc/core/Phases.scala | 14 +++++++++-----
 .../dotty/tools/dotc/transform/Inlining.scala   |  8 +-------
 tests/pos-macros/i18517/Caller.scala            | 17 +++++++++++++++++
 tests/pos-macros/i18517/Macro.scala             |  7 +++++++
 tests/pos-macros/i18517/User.scala              |  6 ++++++
 5 files changed, 40 insertions(+), 12 deletions(-)
 create mode 100644 tests/pos-macros/i18517/Caller.scala
 create mode 100644 tests/pos-macros/i18517/Macro.scala
 create mode 100644 tests/pos-macros/i18517/User.scala

diff --git a/compiler/src/dotty/tools/dotc/core/Phases.scala b/compiler/src/dotty/tools/dotc/core/Phases.scala
index 5dff95fc51fb..85df3f9f2c18 100644
--- a/compiler/src/dotty/tools/dotc/core/Phases.scala
+++ b/compiler/src/dotty/tools/dotc/core/Phases.scala
@@ -378,14 +378,18 @@ object Phases {
               ()
             else
               run
-          catch case ex: Throwable if !ctx.run.enrichedErrorMessage =>
-            println(ctx.run.enrichErrorMessage(s"unhandled exception while running $phaseName on $unit"))
-            throw ex
+            buf += unitCtx.compilationUnit
+          catch
+            case _: CompilationUnit.SuspendException => // this unit will be run again in `Run#compileSuspendedUnits`
+            case ex: Throwable if !ctx.run.enrichedErrorMessage =>
+              println(ctx.run.enrichErrorMessage(s"unhandled exception while running $phaseName on $unit"))
+              throw ex
           finally ctx.run.advanceUnit()
-          buf += unitCtx.compilationUnit
         end if
       end for
-      buf.result()
+      val res = buf.result()
+      ctx.run.nn.checkSuspendedUnits(res)
+      res
     end runOn
 
     /** Convert a compilation unit's tree to a string; can be overridden */
diff --git a/compiler/src/dotty/tools/dotc/transform/Inlining.scala b/compiler/src/dotty/tools/dotc/transform/Inlining.scala
index 335d5a38931a..751636c7d806 100644
--- a/compiler/src/dotty/tools/dotc/transform/Inlining.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Inlining.scala
@@ -36,13 +36,7 @@ class Inlining extends MacroTransform, IdentityDenotTransformer {
 
   override def run(using Context): Unit =
     if ctx.compilationUnit.needsInlining || ctx.compilationUnit.hasMacroAnnotations then
-      try super.run
-      catch case _: CompilationUnit.SuspendException => ()
-
-  override def runOn(units: List[CompilationUnit])(using Context): List[CompilationUnit] =
-    val newUnits = super.runOn(units).filterNot(_.suspended)
-    ctx.run.nn.checkSuspendedUnits(newUnits)
-    newUnits
+      super.run
 
   override def checkPostCondition(tree: Tree)(using Context): Unit =
     tree match {
diff --git a/tests/pos-macros/i18517/Caller.scala b/tests/pos-macros/i18517/Caller.scala
new file mode 100644
index 000000000000..3f5ce9eee903
--- /dev/null
+++ b/tests/pos-macros/i18517/Caller.scala
@@ -0,0 +1,17 @@
+package dummy
+
+trait BG {
+  val   description: { type Structure }
+  type  Structure =  description.Structure
+}
+
+abstract class Caller extends BG {
+  type Foo >: this.type <: this.type
+
+  transparent inline def generate2() =
+    ${Macro.impl() }
+
+  final val description = {
+    generate2()
+  }
+}
diff --git a/tests/pos-macros/i18517/Macro.scala b/tests/pos-macros/i18517/Macro.scala
new file mode 100644
index 000000000000..d18b07e910a5
--- /dev/null
+++ b/tests/pos-macros/i18517/Macro.scala
@@ -0,0 +1,7 @@
+package dummy
+
+import scala.quoted.*
+
+object Macro:
+  def impl()(using quotes:Quotes) : Expr[Any] =
+    '{ null }
diff --git a/tests/pos-macros/i18517/User.scala b/tests/pos-macros/i18517/User.scala
new file mode 100644
index 000000000000..8216c581937b
--- /dev/null
+++ b/tests/pos-macros/i18517/User.scala
@@ -0,0 +1,6 @@
+package dummy
+
+trait User:
+  final def bar(cell:Any) : Unit =
+    (cell: cell.type) match
+      case c: (Caller & cell.type) => ()