Intrinsify StringContext.f

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -553,6 +553,9 @@ class Definitions {
     @tu lazy val Seq_length       : Symbol = SeqClass.requiredMethod(nme.length)
     @tu lazy val Seq_toSeq        : Symbol = SeqClass.requiredMethod(nme.toSeq)
 
+  @tu lazy val StringOps: Symbol = requiredClass("scala.collection.StringOps")
+    @tu lazy val StringOps_format: Symbol  = StringOps.requiredMethod(nme.format)
+
   @tu lazy val ArrayType: TypeRef = requiredClassRef("scala.Array")
   def ArrayClass(using Context): ClassSymbol = ArrayType.symbol.asClass
     @tu lazy val Array_apply     : Symbol = ArrayClass.requiredMethod(nme.apply)
@@ -684,7 +687,13 @@ class Definitions {
   @tu lazy val SerializableType: TypeRef       = JavaSerializableClass.typeRef
   def SerializableClass(using Context): ClassSymbol = SerializableType.symbol.asClass
 
-   @tu lazy val JavaEnumClass: ClassSymbol = {
+  @tu lazy val JavaBigIntegerClass: ClassSymbol = requiredClass("java.math.BigInteger")
+  @tu lazy val JavaBigDecimalClass: ClassSymbol = requiredClass("java.math.BigDecimal")
+  @tu lazy val JavaCalendarClass: ClassSymbol = requiredClass("java.util.Calendar")
+  @tu lazy val JavaDateClass: ClassSymbol = requiredClass("java.util.Date")
+  @tu lazy val JavaFormattableClass: ClassSymbol = requiredClass("java.util.Formattable")
+
+  @tu lazy val JavaEnumClass: ClassSymbol = {
     val cls = requiredClass("java.lang.Enum")
     // jl.Enum has a single constructor protected(name: String, ordinal: Int).
     // We remove the arguments from the primary constructor, and enter
@@ -733,9 +742,6 @@ class Definitions {
     @tu lazy val StringContextModule_standardInterpolator: Symbol = StringContextModule.requiredMethod(nme.standardInterpolator)
     @tu lazy val StringContextModule_processEscapes: Symbol = StringContextModule.requiredMethod(nme.processEscapes)
 
-  @tu lazy val InternalStringContextMacroModule: Symbol = requiredModule("dotty.internal.StringContextMacro")
-    @tu lazy val InternalStringContextMacroModule_f: Symbol = InternalStringContextMacroModule.requiredMethod(nme.f)
-
   @tu lazy val PartialFunctionClass: ClassSymbol = requiredClass("scala.PartialFunction")
     @tu lazy val PartialFunction_isDefinedAt: Symbol = PartialFunctionClass.requiredMethod(nme.isDefinedAt)
     @tu lazy val PartialFunction_applyOrElse: Symbol = PartialFunctionClass.requiredMethod(nme.applyOrElse)

compiler/src/dotty/tools/dotc/core/StdNames.scala

@@ -477,6 +477,7 @@ object StdNames {
     val flagsFromBits : N       = "flagsFromBits"
     val flatMap: N              = "flatMap"
     val foreach: N              = "foreach"
+    val format: N               = "format"
     val fromDigits: N           = "fromDigits"
     val fromProduct: N          = "fromProduct"
     val genericArrayOps: N      = "genericArrayOps"

compiler/src/dotty/tools/dotc/transform/localopt/StringInterpolatorOpt.scala

@@ -7,8 +7,9 @@ import dotty.tools.dotc.core.Decorators._
 import dotty.tools.dotc.core.Constants.Constant
 import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.core.StdNames._
+import dotty.tools.dotc.core.NameKinds._
 import dotty.tools.dotc.core.Symbols._
-import dotty.tools.dotc.core.Types.MethodType
+import dotty.tools.dotc.core.Types._
 import dotty.tools.dotc.transform.MegaPhase.MiniPhase
 
 /**
@@ -116,6 +117,7 @@ class StringInterpolatorOpt extends MiniPhase {
     val sym = tree.symbol
     val isInterpolatedMethod = // Test names first to avoid loading scala.StringContext if not used
       (sym.name == nme.raw_ && sym.eq(defn.StringContext_raw)) ||
+      (sym.name == nme.f && sym.eq(defn.StringContext_f)) ||
       (sym.name == nme.s && sym.eq(defn.StringContext_s))
     if (isInterpolatedMethod)
       tree match {
@@ -132,6 +134,11 @@ class StringInterpolatorOpt extends MiniPhase {
             if (!str.const.stringValue.isEmpty) concat(str)
           }
           result
+        case Apply(intp, args :: Nil) if sym.eq(defn.StringContext_f) =>
+          val partsStr = StringContextChecker.checkedParts(intp, args).mkString
+          resolveConstructor(defn.StringOps.typeRef, List(Literal(Constant(partsStr))))
+            .select(nme.format)
+            .appliedTo(args)
         // Starting with Scala 2.13, s and raw are macros in the standard
         // library, so we need to expand them manually.
         // sc.s(args)    -->   standardInterpolator(processEscapes, args, sc.parts)

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -3257,21 +3257,10 @@ class Typer extends Namer
         if ((inlined ne tree) && errorCount == ctx.reporter.errorCount) readaptSimplified(inlined)
         else inlined
       }
-      else if tree.symbol.name == nme.f && tree.symbol == defn.StringContext_f then
-        // To avoid forcing StringContext_f when compiling StingContex
-        // we test the name before accession symbol StringContext_f.
-
-        // As scala.StringContext.f is defined in the standard library which
-        // we currently do not bootstrap we cannot implement the macro in the library.
-        // To overcome the current limitation we intercept the call and rewrite it into
-        // a call to dotty.internal.StringContext.f which we can implement using the new macros.
-        // As the macro is implemented in the bootstrapped library, it can only be used from the bootstrapped compiler.
-        val Apply(TypeApply(Select(sc, _), _), args) = tree
-        val newCall = ref(defn.InternalStringContextMacroModule_f).appliedTo(sc).appliedToArgs(args).withSpan(tree.span)
-        readaptSimplified(Inliner.inlineCall(newCall))
       else if (tree.symbol.isScala2Macro &&
-               // raw and s are eliminated by the StringInterpolatorOpt phase
+               // `raw`, `f` and `s` are eliminated by the StringInterpolatorOpt phase
               tree.symbol != defn.StringContext_raw &&
+              tree.symbol != defn.StringContext_f &&
               tree.symbol != defn.StringContext_s)
         if (ctx.settings.XignoreScala2Macros.value) {
           report.warning("Scala 2 macro cannot be used in Dotty, this call will crash at runtime. See https://dotty.epfl.ch/docs/reference/dropped-features/macros.html", tree.srcPos.startPos)

project/Build.scala

@@ -1045,7 +1045,6 @@ object Build {
             )).get
 
           ++ (dir / "js/src/test/scala/org/scalajs/testsuite/javalib" ** (("*.scala": FileFilter)
-            -- "FormatterJSTest.scala" // compile error with the f"" interpolator
             -- "ObjectJSTest.scala" // non-native JS classes
             )).get
 

tests/neg/f-interpolator-neg.scala

@@ -0,0 +1,83 @@
+object Test {
+
+  def numberArgumentsTests(s : String, d : Int) = {
+    new StringContext().f() // error
+    new StringContext("", " is ", "%2d years old").f(s) // error
+    new StringContext("", " is ", "%2d years old").f(s, d, d) // error
+    new StringContext("", "").f() // error
+  }
+
+  def interpolationMismatches(s : String, f : Double, b : Boolean) = {
+    f"$s%b" // error
+    f"$s%c" // error
+    f"$f%c" // error
+    f"$s%x" // error
+    f"$b%d" // error
+    f"$s%d" // error
+    f"$f%o" // error
+    f"$s%e" // error
+    f"$b%f" // error
+    f"$s%i" // error
+  }
+
+  def flagMismatches(s : String, c : Char, d : Int, f : Double, t : java.util.Date) = {
+    f"$s%+ 0,(s" // error
+    f"$c%#+ 0,(c" // error
+    f"$d%#d" // error
+    f"$d%,x" // error
+    f"$d%+ (x" // error
+    f"$f%,(a" // error
+    f"$t%#+ 0,(tT" // error
+    f"%-#+ 0,(n" // error
+    f"%#+ 0,(%" // error
+  }
+
+  def badPrecisions(c : Char, d : Int, f : Double, t : java.util.Date) = {
+    f"$c%.2c" // error
+    f"$d%.2d" // error
+    f"%.2%" // error
+    f"%.2n" // error
+    f"$f%.2a" // error
+    f"$t%.2tT" // error
+  }
+
+  def badIndexes() = {
+    f"%<s" // error
+    f"%<c" // error
+    f"%<tT" // error
+    f"${8}%d ${9}%d %3$$d" // error
+    f"${8}%d ${9}%d%0$$d" // error
+  }
+
+  def warnings(s : String) = {
+    f"${8}%d ${9}%1$$d"
+    f"$s%s $s%s %1$$<s"
+    f"$s%s $s%1$$s"
+  }
+
+  def badArgTypes(s : String) = {
+    f"$s%#s" // error
+  }
+
+  def misunderstoodConversions(t : java.util.Date, s : String) = {
+    f"$t%tG" // error
+    f"$t%t" // error
+    f"$s%10.5" // error
+  }
+
+  def otherBrainFailures(d : Int) = {
+    f"${d}random-leading-junk%d" // error
+    f"%1$$n"
+    f"%1$$d" // error
+    f"blablablabla %% %.2d" // error
+    f"blablablabla %.2b %%" // error
+
+    f"ana${3}%.2f%2${true}%bb" // error
+    f"ac{2c{2{c.ca "
+
+    f"b%c.%2ii%iin" // error
+    f"b}22%2.c<{%{"  // error
+    f"%%bci.2${'i'}%..2c2" // error
+  }
+
+}