Add missing version of ValDef.let which also accepts flags to Quotes API (#23388)

Author: jchyb

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -369,6 +369,12 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       def unapply(vdef: ValDef): (String, TypeTree, Option[Term]) =
         (vdef.name.toString, vdef.tpt, optional(vdef.rhs))
 
+      def let(owner: Symbol, name: String, rhs: Term, flags: Flags)(body: Ref => Term): Term =
+        Symbol.checkValidFlags(flags.toTermFlags, Flags.validValInLetFlags)
+        val vdef = tpd.SyntheticValDef(name.toTermName, rhs, flags)(using ctx.withOwner(owner))
+        val ref = tpd.ref(vdef.symbol).asInstanceOf[Ref]
+        Block(List(vdef), body(ref))
+
       def let(owner: Symbol, name: String, rhs: Term)(body: Ref => Term): Term =
         val vdef = tpd.SyntheticValDef(name.toTermName, rhs)(using ctx.withOwner(owner))
         val ref = tpd.ref(vdef.symbol).asInstanceOf[Ref]
@@ -2863,7 +2869,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
       def noSymbol: Symbol = dotc.core.Symbols.NoSymbol
 
-      private inline def checkValidFlags(inline flags: Flags, inline valid: Flags): Unit =
+      private[QuotesImpl] inline def checkValidFlags(inline flags: Flags, inline valid: Flags): Unit =
         xCheckMacroAssert(
           flags <= valid,
           s"Received invalid flags. Expected flags ${flags.show} to only contain a subset of ${valid.show}."
@@ -3250,7 +3256,8 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       private[QuotesImpl] def validMethodFlags: Flags = Private | Protected | Override | Deferred | Final | Method | Implicit | Given | Local | AbsOverride | JavaStatic | Synthetic | Artifact // Flags that could be allowed: Synthetic | ExtensionMethod | Exported | Erased | Infix | Invisible
       // Keep: aligned with Quotes's `newVal` doc
       private[QuotesImpl] def validValFlags: Flags = Private | Protected | Override | Deferred | Final | Param | Implicit | Lazy | Mutable | Local | ParamAccessor | Module | Package | Case | CaseAccessor | Given | Enum | AbsOverride | JavaStatic | Synthetic | Artifact // Flags that could be added: Synthetic | Erased | Invisible
-
+      // Keep: aligned with Quotes's `let` doc
+      private[QuotesImpl] def validValInLetFlags: Flags = Final | Implicit | Lazy | Mutable | Given | Synthetic
       // Keep: aligned with Quotes's `newBind` doc
       private[QuotesImpl] def validBindFlags: Flags = Case // Flags that could be allowed: Implicit | Given | Erased
 

library/src/scala/quoted/Quotes.scala

@@ -682,6 +682,22 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       def copy(original: Tree)(name: String, tpt: TypeTree, rhs: Option[Term]): ValDef
       def unapply(vdef: ValDef): (String, TypeTree, Option[Term])
 
+      /** Creates a block `{ val <name> = <rhs: Term>; <body(x): Term> }`
+       *
+       *  Usage:
+       *  ```
+       *  ValDef.let(owner, "x", rhs1, Flags.Lazy) { x =>
+       *    ValDef.let(x.symbol.owner, "y", rhs2, Flags.Mutable) { y =>
+       *      // use `x` and `y`
+       *    }
+       *  }
+       *  ```
+       *
+       *  @param flags extra flags to with which the symbol should be constructed. Can be `Final | Implicit | Lazy | Mutable | Given | Synthetic`
+       */
+      // Keep: `flags` doc aligned with QuotesImpl's `validValInLetFlags`
+      def let(owner: Symbol, name: String, rhs: Term, flags: Flags)(body: Ref => Term): Term
+
       /** Creates a block `{ val <name> = <rhs: Term>; <body(x): Term> }`
        *
        *  Usage:

project/MiMaFilters.scala

@@ -22,8 +22,10 @@ object MiMaFilters {
 
         ProblemFilters.exclude[DirectMissingMethodProblem]("scala.Conversion.underlying"),
         ProblemFilters.exclude[MissingClassProblem]("scala.Conversion$"),
-        
+
         ProblemFilters.exclude[MissingClassProblem]("scala.annotation.stableNull"),
+
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ValDefModule.let"),
       ),
 
       // Additions since last LTS
@@ -129,6 +131,7 @@ object MiMaFilters {
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#MethodTypeMethods.methodTypeKind"),
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#MethodTypeMethods.isContextual"),
           ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ImplicitsModule.searchIgnoring"),
+          ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ValDefModule.let"),
           // Change `experimental` annotation to a final class
           ProblemFilters.exclude[FinalClassProblem]("scala.annotation.experimental"),
         ),

tests/neg-macros/i23008.check

@@ -5,8 +5,8 @@
   |                 Exception occurred while executing macro expansion.
   |                 java.lang.IllegalArgumentException: requirement failed: value of StringConstant cannot be `null`
   |                 	at scala.Predef$.require(Predef.scala:337)
-  |                 	at scala.quoted.runtime.impl.QuotesImpl$reflect$StringConstant$.apply(QuotesImpl.scala:2534)
-  |                 	at scala.quoted.runtime.impl.QuotesImpl$reflect$StringConstant$.apply(QuotesImpl.scala:2533)
+  |                 	at scala.quoted.runtime.impl.QuotesImpl$reflect$StringConstant$.apply(QuotesImpl.scala:2540)
+  |                 	at scala.quoted.runtime.impl.QuotesImpl$reflect$StringConstant$.apply(QuotesImpl.scala:2539)
   |                 	at scala.quoted.ToExpr$StringToExpr.apply(ToExpr.scala:80)
   |                 	at scala.quoted.ToExpr$StringToExpr.apply(ToExpr.scala:78)
   |                 	at scala.quoted.Expr$.apply(Expr.scala:70)

tests/run-macros/ValDef-let-flags.check

@@ -0,0 +1 @@
+x: 1, y: string

tests/run-macros/ValDef-let-flags/Macro_1.scala

@@ -0,0 +1,15 @@
+import scala.quoted._
+
+object Macro:
+  inline def makeBlock(): Unit = ${makeBlockImpl}
+  def makeBlockImpl(using Quotes): Expr[Unit] = {
+    import quotes.reflect._
+    ValDef.let(Symbol.spliceOwner, "x", '{0}.asTerm, Flags.Mutable) { x =>
+      ValDef.let(Symbol.spliceOwner, "y", '{"string"}.asTerm, Flags.Lazy) { y =>
+        '{
+          ${Assign(x, '{1}.asTerm).asExpr}
+          println("x: " + ${x.asExprOf[Int]} + ", y: " + ${y.asExprOf[String]})
+        }.asTerm
+      }
+    }.asExprOf[Unit]
+  }

tests/run-macros/ValDef-let-flags/Test_2.scala

@@ -0,0 +1 @@
+@main def Test = Macro.makeBlock()