From 467cbc7856411667bc4948a739f0f22b2d6ac7d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Pa=C5=82ka?= <prolativus@gmail.com>
Date: Tue, 24 Aug 2021 15:04:52 +0200
Subject: [PATCH] Disallow inline secondary constructors

---
 compiler/src/dotty/tools/dotc/typer/Inliner.scala | 2 ++
 compiler/src/dotty/tools/dotc/typer/Typer.scala   | 2 ++
 tests/neg/i12986a/Bar.scala                       | 2 ++
 tests/neg/i12986a/Test.scala                      | 1 +
 tests/neg/i12986b.scala                           | 4 ++++
 5 files changed, 11 insertions(+)
 create mode 100644 tests/neg/i12986a/Bar.scala
 create mode 100644 tests/neg/i12986a/Test.scala
 create mode 100644 tests/neg/i12986b.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/Inliner.scala b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
index cab9f397d507..7d5b26a7be85 100644
--- a/compiler/src/dotty/tools/dotc/typer/Inliner.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Inliner.scala
@@ -97,6 +97,8 @@ object Inliner {
     if tree.symbol.isExperimental then
       Feature.checkExperimentalDef(tree.symbol, tree)
 
+    if tree.symbol.isConstructor then return tree // error already reported for the inline constructor definition
+
     /** Set the position of all trees logically contained in the expansion of
      *  inlined call `call` to the position of `call`. This transform is necessary
      *  when lifting bindings from the expansion to the outside of the call.
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 6c13afa219b8..c04239aafefa 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -2164,6 +2164,8 @@ class Typer extends Namer
       PrepareInlineable.registerInlineInfo(sym, rhsToInline)
 
     if sym.isConstructor then
+      if sym.is(Inline) then
+        report.error("constructors cannot be `inline`", ddef)
       if sym.isPrimaryConstructor then
         if sym.owner.is(Case) then
           for
diff --git a/tests/neg/i12986a/Bar.scala b/tests/neg/i12986a/Bar.scala
new file mode 100644
index 000000000000..fcc12aca6259
--- /dev/null
+++ b/tests/neg/i12986a/Bar.scala
@@ -0,0 +1,2 @@
+class Bar(i: Int):
+  inline def this() = this(0) // error
diff --git a/tests/neg/i12986a/Test.scala b/tests/neg/i12986a/Test.scala
new file mode 100644
index 000000000000..84399837c008
--- /dev/null
+++ b/tests/neg/i12986a/Test.scala
@@ -0,0 +1 @@
+val bar = new Bar()
diff --git a/tests/neg/i12986b.scala b/tests/neg/i12986b.scala
new file mode 100644
index 000000000000..d8de9dbfb51c
--- /dev/null
+++ b/tests/neg/i12986b.scala
@@ -0,0 +1,4 @@
+class Bar(i: Int):
+  transparent inline def this() = this(0) // error
+
+val bar = Bar()