Merge pull request #16161 from RasmusWL/js/strict-mode

JS: Parser: Never run in strict mode

javascript/extractor/src/com/semmle/jcorn/Parser.java

@@ -244,7 +244,13 @@ public Parser(Options options, String input, int startPos) {
     this.exprAllowed = true;
 
     // Figure out if it's a module code.
-    this.strict = this.inModule = options.sourceType().equals("module");
+    this.inModule = options.sourceType().equals("module");
+
+    // We don't care to report syntax errors in code that might be using strict mode. In
+    // the end, we don't know whether that code is put through additional build steps
+    // causing our alleged syntax errors to disappear. Therefore, we hardcode
+    // this.strict to false.
+    this.strict = false;
 
     // Used to signify the start of a potential arrow function
     this.potentialArrowAt = -1;
@@ -323,18 +329,13 @@ protected void next() {
     this.nextToken();
   }
 
-  // Toggle strict mode. Re-reads the next number or string to please
-  // pedantic tests (`"use strict"; 010;` should fail).
+  // DEPRECATED. When we respected strict mode, this method was used to toggle strict
+  // mode (and would re-read the next number or string to please pedantic tests (`"use
+  // strict"; 010;` should fail)).
 
   public void setStrict(boolean strict) {
-    this.strict = strict;
-    if (this.type != TokenType.num && this.type != TokenType.string) return;
-    this.pos = this.start;
-    while (this.pos < this.lineStart) {
-      this.lineStart = this.input.lastIndexOf("\n", this.lineStart - 2) + 1;
-      --this.curLine;
-    }
-    this.nextToken();
+    // always false
+    return;
   }
 
   public TokContext curContext() {
@@ -3107,7 +3108,7 @@ protected BlockStatement parseBlock(boolean allowStrict) {
       if (stmt != null) body.add(stmt);
       if (first && allowStrict && this.isUseStrict(stmt)) {
         oldStrict = this.strict;
-        this.setStrict(this.strict = true);
+        this.setStrict(true);
       }
       first = false;
     }

javascript/extractor/src/com/semmle/js/extractor/Main.java

@@ -41,7 +41,7 @@ public class Main {
    * A version identifier that should be updated every time the extractor changes in such a way that
    * it may produce different tuples for the same file under the same {@link ExtractorConfig}.
    */
-  public static final String EXTRACTOR_VERSION = "2023-10-13";
+  public static final String EXTRACTOR_VERSION = "2024-04-17";
 
   public static final Pattern NEWLINE = Pattern.compile("\n");
 

javascript/extractor/tests/strictmode/output/trap/assignargs.js.trap

@@ -196,29 +196,5 @@ successor(#20045,#20048)
 successor(#20057,#20041)
 successor(#20038,#20037)
 successor(#20054,#20038)
-#20059=*
-js_parse_errors(#20059,#20001,"Error: Assigning to arguments in strict mode","  arguments = 42;
-")
-#20060=@"loc,{#10000},3,3,3,3"
-locations_default(#20060,#10000,3,3,3,3)
-hasLocation(#20059,#20060)
-#20061=*
-lines(#20061,#20001,"function f() {","
-")
-hasLocation(#20061,#20003)
-#20062=*
-lines(#20062,#20001,"  'use strict';","
-")
-hasLocation(#20062,#20005)
-indentation(#10000,2," ",2)
-#20063=*
-lines(#20063,#20001,"  arguments = 42;","
-")
-hasLocation(#20063,#20007)
-indentation(#10000,3," ",2)
-#20064=*
-lines(#20064,#20001,"}","")
-hasLocation(#20064,#20009)
-numlines(#20001,4,0,0)
 numlines(#10000,4,4,0)
 filetype(#10000,"javascript")

javascript/ql/src/change-notes/2024-04-17-strict-mode.md

@@ -0,0 +1,7 @@
+---
+category: minorAnalysis
+---
+* The JavaScript extractor will on longer report syntax errors related to "strict mode".
+  Files containing such errors are now being fully analyzed along with other sources files.
+  This improves our support for source files that technically break the "strict mode" rules,
+  but where a build steps transforms the code such that it ends up working at runtime.