fix(compiler): throw an error if variable with the same name is already defined. (#7209)

* fix(compiler): throw an error if variable with the same name is already defined. Closes #6492

* fix(compiler): Clean up formatting for issue #6492

* fix(compiler): throw an error if reference with the same name is already defined.

Closes #6492

modules/@angular/compiler/src/template_parser.ts

@@ -155,6 +155,9 @@ export class TemplateParser {
     } else {
       result = [];
     }
+
+    this._assertNoReferenceDuplicationOnTemplate(result, errors);
+
     if (errors.length > 0) {
       return new TemplateParseResult(result, errors);
     }
@@ -164,6 +167,25 @@ export class TemplateParser {
     }
     return new TemplateParseResult(result, errors);
   }
+
+  _assertNoReferenceDuplicationOnTemplate(result:any[], errors:TemplateParseError[]):void {
+    const existingReferences = [];
+    result
+      .filter(element => !!element.references)
+      .forEach(element => element.references.forEach(reference=> {
+        const name = reference.name;
+        if (existingReferences.indexOf(name) < 0) {
+          existingReferences.push(name);
+        }
+        else {
+          const error = new TemplateParseError(
+            `Reference "#${name}" is defined several times`,
+            reference.sourceSpan,
+            ParseErrorLevel.FATAL);
+          errors.push(error);
+        }
+      }));
+  }
 }
 
 class TemplateParseVisitor implements HtmlAstVisitor {
@@ -522,9 +544,11 @@ class TemplateParseVisitor implements HtmlAstVisitor {
 
   private _parseVariable(identifier: string, value: string, sourceSpan: ParseSourceSpan,
                          targetVars: VariableAst[]) {
+
     if (identifier.indexOf('-') > -1) {
       this._reportError(`"-" is not allowed in variable names`, sourceSpan);
     }
+
     targetVars.push(new VariableAst(identifier, value, sourceSpan));
   }
 
@@ -533,6 +557,7 @@ class TemplateParseVisitor implements HtmlAstVisitor {
     if (identifier.indexOf('-') > -1) {
       this._reportError(`"-" is not allowed in reference names`, sourceSpan);
     }
+
     targetRefs.push(new ElementOrDirectiveRef(identifier, value, sourceSpan));
   }
 

modules/@angular/compiler/test/template_parser_spec.ts

@@ -822,6 +822,16 @@ There is no directive with "exportAs" set to "dirA" ("<div [ERROR ->]#a="dirA"><
 "let-" is only supported on template elements. ("<div [ERROR ->]let-a></div>"): TestComp@0:5`);
         });
 
+        it('should report duplicate reference names', () => {

+          expect(() => parse('<div #a></div><div #a></div>', []))

+            .toThrowError(`Template parse errors:
+Reference "#a" is defined several times ("<div #a></div><div [ERROR ->]#a></div>"): TestComp@0:19`);

+        });
+
+


        it('should not throw error when there is same reference name in different templates', () => {

+            expect(() => parse('<div #a><template #a><span>OK</span></template></div>', [])).not.toThrowError();

+        });
+
         it('should assign references with empty value to components', () => {
           var dirA = CompileDirectiveMetadata.create({
             selector: '[a]',

modules/@angular/core/test/linker/query_integration_spec.ts

@@ -1059,11 +1059,11 @@ class NeedsContentChildWithRead {
 
 @Component({
   selector: 'needs-view-children-read',
-  template: '<div #q text="va"></div><div #q text="vb"></div>',
+  template: '<div #q text="va"></div><div #w text="vb"></div>',
   directives: [TextDirective]
 })
 class NeedsViewChildrenWithRead {
-  @ViewChildren('q', {read: TextDirective}) textDirChildren: QueryList<TextDirective>;
+  @ViewChildren('q,w', {read: TextDirective}) textDirChildren: QueryList<TextDirective>;
   @ViewChildren('nonExisting', {read: TextDirective}) nonExistingVar: QueryList<TextDirective>;
 }