showAst annotation interpreted by commons-analyzer

Author: ghik

commons-analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerPlugin.scala

@@ -11,7 +11,8 @@ final class AnalyzerPlugin(val global: Global) extends Plugin { plugin =>
     new VarargsAtLeast[global.type](global),
     new CheckMacroPrivate[global.type](global),
     new ExplicitGenerics[global.type](global),
-    new ValueEnumExhaustiveMatch[global.type](global)
+    new ValueEnumExhaustiveMatch[global.type](global),
+    new ShowAst[global.type](global)
   )
   val rulesByName = rules.map(r => (r.name, r)).toMap
 

commons-analyzer/src/main/scala/com/avsystem/commons/analyzer/AnalyzerRule.scala

@@ -6,11 +6,12 @@ import java.io.{PrintWriter, StringWriter}
 import scala.tools.nsc.Global
 import scala.util.control.NonFatal
 
-abstract class AnalyzerRule[C <: Global with Singleton](val global: C, val name: String) {
+abstract class AnalyzerRule[C <: Global with Singleton](
+  val global: C, val name: String, defaultLevel: Level = Level.Warn) {
 
   import global._
 
-  var level: Level = Level.Warn
+  var level: Level = defaultLevel
 
   protected def classType(fullName: String) =
     try rootMirror.staticClass(fullName).asType.toType.erasure catch {

commons-analyzer/src/main/scala/com/avsystem/commons/analyzer/ShowAst.scala

@@ -0,0 +1,30 @@
+package com.avsystem.commons
+package analyzer
+
+import scala.tools.nsc.Global
+
+class ShowAst[C <: Global with Singleton](g: C) extends AnalyzerRule(g, "showAst", Level.Error) {
+
+  import global._
+
+  lazy val showAstAnnotType: Type = classType("com.avsystem.commons.annotation.showAst")
+
+  def analyze(unit: CompilationUnit) = if (showAstAnnotType != NoType) {
+    def analyzeTree(tree: Tree): Unit = analyzer.macroExpandee(tree) match {
+      case `tree` | EmptyTree =>
+        tree match {
+          case Annotated(annot, arg) if annot.tpe <:< showAstAnnotType =>
+            report(arg.pos, showCode(arg))
+          case Typed(expr, tpt) if tpt.tpe.annotations.exists(_.tpe <:< showAstAnnotType) =>
+            report(expr.pos, showCode(expr))
+          case _: MemberDef if tree.symbol.annotations.exists(_.tpe <:< showAstAnnotType) =>
+            report(tree.pos, showCode(tree))
+          case _ =>
+        }
+        tree.children.foreach(analyzeTree)
+      case prevTree =>
+        analyzeTree(prevTree)
+    }
+    analyzeTree(unit.body)
+  }
+}

commons-annotations/src/main/scala/com/avsystem/commons/annotation/showAst.scala

@@ -0,0 +1,11 @@
+package com.avsystem.commons
+package annotation
+
+import scala.annotation.StaticAnnotation
+
+/**
+  * When applied on a definition (`class`, `object`, `def`, `val`, etc.) or expression, will cause the
+  * AVSystem static analyzer to print compilation error with AST of annotated code fragment.
+  * This is useful primarily for debugging macro expansions.
+  */
+class showAst extends StaticAnnotation

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "1.28.0"
+version in ThisBuild := "1.28.1"