Fix bug 1991, variable resolution in string interpolation

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 7076 matching lines @@
 // If the name cannot be resolved, turn it into an instance field access
 // if we're compiling an instance method, or issue an error message
 // if we're compiling a static method.
 AstNode* Parser::ResolveVarOrField(intptr_t ident_pos, const String& ident) {
   TRACE_PARSER("ResolveVarOrField");
   // First try to find the variable in the local scope (block scope or
   // class scope).
   AstNode* var_or_field = NULL;
   ResolveIdentInLocalScope(ident_pos, ident, &var_or_field);
   if (var_or_field == NULL) {
-    // Not found in the local scope, so try finding the variable in the
-    // library scope (current library and all libraries imported by it).
+    // Check whether the identifier is a type parameter. Type parameters
+    // can never be used in primary expressions.
+    const Class& scope_class = Class::Handle(TypeParametersScopeClass());
+    if (!scope_class.IsNull()) {
+      TypeParameter& type_param = TypeParameter::Handle(
+          scope_class.LookupTypeParameter(ident, ident_pos));
+      if (!type_param.IsNull()) {
+        String& type_param_name = String::Handle(type_param.Name());
+        ErrorMsg(ident_pos, "illegal use of type parameter %s",
+                 type_param_name.ToCString());
+      }
+    }
+    // Not found in the local scope, and the name is not a type parameter.
+    // Try finding the variable in the library scope (current library
+    // and all libraries imported by it).
     QualIdent qual_ident;
     qual_ident.lib_prefix = NULL;
     qual_ident.ident_pos = ident_pos;
     qual_ident.ident = &(String::ZoneHandle(ident.raw()));
     var_or_field = ResolveIdentInLibraryScope(library_,
                                               qual_ident,
                                               kResolveIncludingImports);
   }
   if (var_or_field->IsPrimaryNode()) {
     PrimaryNode* primary = var_or_field->AsPrimaryNode();
@@ skipping 1266 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart