Add noUniversalEquality option to DisableSyntax

scalafix-rules/src/main/scala/scalafix/internal/rule/DisableSyntax.scala

@@ -196,6 +196,12 @@ final class DisableSyntax(config: DisableSyntaxConfig)
               "Default args makes it hard to use methods as functions.",
               m.pos)
           }
+      case Term.ApplyInfix(_, t @ Term.Name("=="), _, _)
+          if config.noUniversalEquality =>
+        Seq(noUniversalEqualityDiagnostic(t))
+      case Term.Apply(Term.Select(_, t @ Term.Name("==")), _)
+          if config.noUniversalEquality =>
+        Seq(noUniversalEqualityDiagnostic(t))
     }
     val FinalizeMatcher = DisableSyntax.FinalizeMatcher("noFinalize")
     doc.tree.collect(DefaultMatcher.orElse(FinalizeMatcher)).flatten
@@ -211,11 +217,16 @@ final class DisableSyntax(config: DisableSyntaxConfig)
     LintCategory.error(
       id = "noFinalVal",
       explain = "Final vals cause problems with incremental compilation")
+
   private val noValPatternCategory: LintCategory =
     LintCategory.error(
       id = "noValPatterns",
       explain = "Pattern matching in val assignment can result in match error, " +
         "use \"_ match { ... }\" with a fallback case instead.")
+
+  private def noUniversalEqualityDiagnostic(t: Term.Name): Diagnostic =
+    Diagnostic("==", config.noUniversalEqualityMessage, t.pos)
+
 }
 
 object DisableSyntax {

scalafix-rules/src/main/scala/scalafix/internal/rule/DisableSyntaxConfig.scala

@@ -64,6 +64,15 @@ case class DisableSyntaxConfig(
     @Description(
       "Report error when pattern matching in val assignment with non-tuple patterns.")
     noValPatterns: Boolean = false,
+    @Description(
+      "Report error on `==` (universal equality)"
+    )
+    noUniversalEquality: Boolean = false,
+    @Description(
+      "Reporter message for noUniversalEquality"
+    )
+    noUniversalEqualityMessage: String =
+      "Universal equality should be avoided since it's not typesafe",
     @Description(
       "Report error if the text contents of a source file matches a given regex.")
     @ExampleValue(

scalafix-tests/input/src/main/scala/test/DisableSyntaxMoreRules.scala

@@ -6,6 +6,9 @@ DisableSyntax.noDefaultArgs = true
 DisableSyntax.noValInAbstract = true
 DisableSyntax.noImplicitObject = true
 DisableSyntax.noImplicitConversion = true
+DisableSyntax.noUniversalEquality = true
+DisableSyntax.noUniversalEqualityMessage =
+  "== is not typesafe, use === from cats.Eq instead"
 */
 package test
 
@@ -85,4 +88,15 @@ Default args makes it hard to use methods as functions.
 
   implicit def toString(a: Any): String = a.toString // assert: DisableSyntax.implicitConversion
   implicit def toImplicitString(implicit foo: Foo) = foo.toString // ok
+
+  1 == 2 /* assert: DisableSyntax.==
+    ^^
+    == is not typesafe, use === from cats.Eq instead
+  */
+
+  1.==(2) /* assert: DisableSyntax.==
+    ^^
+    == is not typesafe, use === from cats.Eq instead
+  */
+
 }