[Macros] Use the resolved macro for evaluation.

Don't look up the macro name again when doing expansion; that's already
been done when we found the macro definition.

Author: DougGregor

lib/ASTGen/Sources/ASTGen/Macros.swift

@@ -85,6 +85,7 @@ private func allocateUTF8String(
 @_cdecl("swift_ASTGen_evaluateMacro")
 @usableFromInline
 func evaluateMacro(
+  macroPtr: UnsafeMutablePointer<UInt8>,
   sourceFilePtr: UnsafePointer<UInt8>,
   sourceLocationPtr: UnsafePointer<UInt8>?,
   expandedSourcePointer: UnsafeMutablePointer<UnsafePointer<UInt8>?>,
@@ -117,13 +118,12 @@ func evaluateMacro(
     }
 
     guard let parentSyntax = token.parent,
-      parentSyntax.is(MacroExpansionExprSyntax.self)
+          let parentExpansion = parentSyntax.as(MacroExpansionExprSyntax.self)
     else {
       print("not on a macro expansion node: \(token.recursiveDescription)")
       return -1
     }
 
-    let macroSystem = MacroSystem.exampleSystem
     let converter = SourceLocationConverter(
       file: sourceFile.pointee.fileName, tree: sf
     )
@@ -132,10 +132,15 @@ func evaluateMacro(
       sourceLocationConverter: converter
     )
 
-    let evaluatedSyntax = parentSyntax.evaluateMacro(
-      with: macroSystem, context: context
-    ) { error in
-      /* TODO: Report errors */
+    let evaluatedSyntax: ExprSyntax = macroPtr.withMemoryRebound(to: ExportedMacro.self, capacity: 1) { macro in
+      guard let exprMacro = macro.pointee.macro as? ExpressionMacro.Type else {
+        print("not an expression macro")
+        return ExprSyntax(parentExpansion)
+      }
+
+      let expansion = exprMacro.apply(parentExpansion, in: context)
+      // FIXME: Produce diagnostics.
+      return expansion.rewritten
     }
 
     var evaluatedSyntaxStr = evaluatedSyntax.withoutTrivia().description

lib/Sema/TypeCheckMacros.cpp

@@ -40,7 +40,7 @@ extern "C" void *swift_ASTGen_lookupMacro(const char *macroName);
 extern "C" void swift_ASTGen_destroyMacro(void *macro);
 
 extern "C" ptrdiff_t swift_ASTGen_evaluateMacro(
-    void *sourceFile, const void *sourceLocation,
+    void *macro, void *sourceFile, const void *sourceLocation,
     const char **evaluatedSource, ptrdiff_t *evaluatedSourceLength);
 
 /// Produce the mangled name for the nominal type descriptor of a type
@@ -177,10 +177,10 @@ Expr *swift::expandMacroExpr(
       if (!astGenSourceFile)
         return nullptr;
 
-      // FIXME: Tell ASTGen which macro to use.
       const char *evaluatedSourceAddress;
       ptrdiff_t evaluatedSourceLength;
       swift_ASTGen_evaluateMacro(
+          macroDef.getAsBuiltin(),
           astGenSourceFile, expr->getStartLoc().getOpaquePointerValue(),
           &evaluatedSourceAddress, &evaluatedSourceLength);
       if (!evaluatedSourceAddress)
@@ -206,8 +206,7 @@ Expr *swift::expandMacroExpr(
          /*range*/ Lexer::getCharSourceRangeFromSourceRange(
              sourceMgr, expr->getSourceRange()), ctx, pluginDiags);
       for (auto &diag : pluginDiags) {
-        // FIXME: Switch to DeclName in the diagnostics.
-        auto loc = sourceMgr.getLocForOffset(*bufferID, diag.position);
+\        auto loc = sourceMgr.getLocForOffset(*bufferID, diag.position);
         Diag<DeclName, StringRef> diagID;
         switch (diag.severity) {
         case CompilerPlugin::DiagnosticSeverity::Note: