From 01c39b3204d927e1e52b8b90ce109a275b0ad845 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Kozak?= <b.kozak@avsystem.com>
Date: Thu, 22 Aug 2024 16:41:37 +0200
Subject: [PATCH] add byNameImplicitParameter rule

---
 .../commons/analyzer/AnalyzerPlugin.scala     |  1 +
 .../analyzer/ByNameImplicitParameter.scala    | 18 +++++++++++
 .../analyzer/ByNameParametersTest.scala       | 32 +++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 analyzer/src/main/scala/com/avsystem/commons/analyzer/ByNameImplicitParameter.scala
 create mode 100644 analyzer/src/test/scala/com/avsystem/commons/analyzer/ByNameParametersTest.scala

diff --git a/analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerPlugin.scala b/analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerPlugin.scala
index e91ef8d0c..a3221f2c9 100644
--- a/analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerPlugin.scala
+++ b/analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerPlugin.scala
@@ -59,6 +59,7 @@ final class AnalyzerPlugin(val global: Global) extends Plugin { plugin =>
     new BadSingletonComponent(global),
     new ConstantDeclarations(global),
     new BasePackage(global),
+    new ByNameImplicitParameter(global),
   )
 
   private lazy val rulesByName = rules.map(r => (r.name, r)).toMap
diff --git a/analyzer/src/main/scala/com/avsystem/commons/analyzer/ByNameImplicitParameter.scala b/analyzer/src/main/scala/com/avsystem/commons/analyzer/ByNameImplicitParameter.scala
new file mode 100644
index 000000000..57bf69f00
--- /dev/null
+++ b/analyzer/src/main/scala/com/avsystem/commons/analyzer/ByNameImplicitParameter.scala
@@ -0,0 +1,18 @@
+package com.avsystem.commons
+package analyzer
+
+import scala.tools.nsc.Global
+
+final class ByNameImplicitParameter(g: Global) extends AnalyzerRule(g, "byNameImplicitParameter") {
+
+  import global.*
+
+  private def isByNameImplicit(x: ValDef): Boolean =
+    x.symbol.isImplicit && x.symbol.isByNameParam && !x.symbol.isSynthetic
+  def analyze(unit: CompilationUnit): Unit = unit.body.foreach {
+    case tree: DefDef if !tree.symbol.isSynthetic && tree.vparamss.flatten.exists(isByNameImplicit) =>
+      report(tree.pos, "Implicit by-name parameters are disabled")
+    case _ =>
+  }
+
+}
\ No newline at end of file
diff --git a/analyzer/src/test/scala/com/avsystem/commons/analyzer/ByNameParametersTest.scala b/analyzer/src/test/scala/com/avsystem/commons/analyzer/ByNameParametersTest.scala
new file mode 100644
index 000000000..89e32be68
--- /dev/null
+++ b/analyzer/src/test/scala/com/avsystem/commons/analyzer/ByNameParametersTest.scala
@@ -0,0 +1,32 @@
+package com.avsystem.commons
+package analyzer
+
+import org.scalatest.funsuite.AnyFunSuite
+
+final class ByNameParametersTest extends AnyFunSuite with AnalyzerTest {
+  test("should report by-name implicit parameters") {
+    assertErrors(2,
+      //language=Scala
+      """
+        |object whatever {
+        |  def byName(x: => Int) = x
+        |  def byName(implicit x: => String) = x
+        |  def byName(x: => Int)(implicit y: => Int) = x
+        |  def byName(implicit x: Int) = x
+        |}
+      """.stripMargin
+    )
+  }
+
+  test("should report by-name implicit constructor parameters") {
+    assertErrors(2,
+      //language=Scala
+      """
+        |object whatever {
+        |  class C(x: => Int)(implicit y: => Int, z: String)
+        |  class D(implicit y: => Int, z: => String)
+        |}
+        |""".stripMargin
+    )
+  }
+}
\ No newline at end of file