Merge pull request #1769 from asger-semmle/ts-rest-pattern-default

Approved by esben-semmle

Author: semmle-qlci

javascript/extractor/src/com/semmle/js/parser/TypeScriptASTConverter.java

@@ -2220,7 +2220,7 @@ private Node convertYieldExpression(JsonObject node, SourceLocation loc) throws
    * ObjectExpression} with {@link ObjectPattern} and {@link SpreadElement} with {@link
    * RestElement}.
    */
-  private Expression convertLValue(Expression e) {
+  private Expression convertLValue(Expression e) throws ParseError {
     if (e == null) return null;
 
     SourceLocation loc = e.getLoc();
@@ -2249,8 +2249,14 @@ private Expression convertLValue(Expression e) {
     if (e instanceof ParenthesizedExpression)
       return new ParenthesizedExpression(
           loc, convertLValue(((ParenthesizedExpression) e).getExpression()));
-    if (e instanceof SpreadElement)
-      return new RestElement(e.getLoc(), convertLValue(((SpreadElement) e).getArgument()));
+    if (e instanceof SpreadElement) {
+      Expression argument = convertLValue(((SpreadElement) e).getArgument());
+      if (argument instanceof AssignmentPattern) {
+        throw new ParseError(
+            "Rest patterns cannot have a default value", argument.getLoc().getStart());
+      }
+      return new RestElement(e.getLoc(), argument);
+    }
     return e;
   }
 

javascript/extractor/tests/ts/input/restPatternWithDefault.ts

@@ -0,0 +1,3 @@
+var a: number[];
+var x: number[];
+[...x = a] = a;  // Error, rest element cannot have initializer

javascript/extractor/tests/ts/output/trap/restPatternWithDefault.ts.trap

@@ -0,0 +1,42 @@
+#10000=@"/restPatternWithDefault.ts;sourcefile"
+files(#10000,"/restPatternWithDefault.ts","restPatternWithDefault","ts",0)
+#10001=@"/;folder"
+folders(#10001,"/","")
+containerparent(#10001,#10000)
+#10002=@"loc,{#10000},0,0,0,0"
+locations_default(#10002,#10000,0,0,0,0)
+hasLocation(#10000,#10002)
+#20000=@"global_scope"
+scopes(#20000,0)
+#20001=@"script;{#10000},1,1"
+toplevels(#20001,0)
+#20002=@"loc,{#10000},1,1,1,1"
+locations_default(#20002,#10000,1,1,1,1)
+hasLocation(#20001,#20002)
+#20003=*
+jsParseErrors(#20003,#20001,"Error: Rest patterns cannot have a default value","[...x = a] = a;  // Error, rest element cannot have initializer
+")
+#20004=@"loc,{#10000},3,5,3,5"
+locations_default(#20004,#10000,3,5,3,5)
+hasLocation(#20003,#20004)
+#20005=*
+lines(#20005,#20001,"var a: number[];","
+")
+#20006=@"loc,{#10000},1,1,1,16"
+locations_default(#20006,#10000,1,1,1,16)
+hasLocation(#20005,#20006)
+#20007=*
+lines(#20007,#20001,"var x: number[];","
+")
+#20008=@"loc,{#10000},2,1,2,16"
+locations_default(#20008,#10000,2,1,2,16)
+hasLocation(#20007,#20008)
+#20009=*
+lines(#20009,#20001,"[...x = a] = a;  // Error, rest element cannot have initializer","
+")
+#20010=@"loc,{#10000},3,1,3,63"
+locations_default(#20010,#10000,3,1,3,63)
+hasLocation(#20009,#20010)
+numlines(#20001,3,0,0)
+numlines(#10000,3,0,0)
+filetype(#10000,"typescript")