TS: Support declare modifier for fields

Author: asger-semmle

javascript/extractor/src/com/semmle/js/ast/DeclarationFlags.java

@@ -17,9 +17,10 @@ public class DeclarationFlags {
   public static final int protected_ = 1 << 6;
   public static final int optional = 1 << 7;
   public static final int definiteAssignmentAssertion = 1 << 8;
+  public static final int declareKeyword = 1 << 9;
 
   public static final int none = 0;
-  public static final int numberOfFlags = 9;
+  public static final int numberOfFlags = 10;
 
   public static final List<String> names =
       Arrays.asList(
@@ -31,7 +32,8 @@ public class DeclarationFlags {
           "private",
           "protected",
           "optional",
-          "definiteAssignmentAssertion");
+          "definiteAssignmentAssertion",
+          "declare");
 
   public static final List<String> relationNames =
       Arrays.asList(
@@ -43,7 +45,8 @@ public class DeclarationFlags {
           "hasPrivateKeyword",
           "hasProtectedKeyword",
           "isOptionalMember",
-          "hasDefiniteAssignmentAssertion");
+          "hasDefiniteAssignmentAssertion",
+          "hasDeclareKeyword");
 
   public static boolean isComputed(int flags) {
     return (flags & computed) != 0;
@@ -81,6 +84,10 @@ public static boolean hasDefiniteAssignmentAssertion(int flags) {
     return (flags & definiteAssignmentAssertion) != 0;
   }
 
+  public static boolean hasDeclareKeyword(int flags) {
+    return (flags & declareKeyword) != 0;
+  }
+
   /** Returns a mask with the computed bit set to the value of <tt>enable</tt>. */
   public static int getComputed(boolean enable) {
     return enable ? computed : 0;
@@ -128,6 +135,11 @@ public static int getDefiniteAssignmentAssertion(boolean enable) {
     return enable ? definiteAssignmentAssertion : 0;
   }
 
+  /** Returns a mask with the declare keyword bit set to the value of <tt>enable</tt>. */
+  public static int getDeclareKeyword(boolean enable) {
+    return enable ? declareKeyword : 0;
+  }
+
   /** Returns true if the <tt>n</tt>th bit is set in <tt>flags</tt>. */
   public static boolean hasNthFlag(int flags, int n) {
     return (flags & (1 << n)) != 0;

javascript/extractor/src/com/semmle/js/ast/MemberDefinition.java

@@ -75,6 +75,11 @@ public boolean hasReadonlyKeyword() {
     return DeclarationFlags.isReadonly(flags);
   }
 
+  /** Returns true if this has the <tt>declare</tt> modifier. */
+  public boolean hasDeclareKeyword() {
+    return DeclarationFlags.hasDeclareKeyword(flags);
+  }
+
   /**
    * Returns the expression denoting the name of the member, or {@code null} if this is a
    * call/construct signature.

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

@@ -1410,6 +1410,10 @@ public Label visit(MemberDefinition<?> nd, Context c) {
         }
       }
 
+      if (nd.hasDeclareKeyword()) {
+        trapwriter.addTuple("hasDeclareKeyword", methkey);
+      }
+
       return methkey;
     }
 

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

@@ -2009,6 +2009,9 @@ private Node convertPropertyDeclaration(JsonObject node, String kind, SourceLoca
     if (node.get("exclamationToken") != null) {
       flags |= DeclarationFlags.definiteAssignmentAssertion;
     }
+    if (hasModifier(node, "DeclareKeyword")) {
+      flags |= DeclarationFlags.declareKeyword;
+    }
     FieldDefinition fieldDefinition =
         new FieldDefinition(
             loc,

javascript/ql/src/semmle/javascript/Classes.qll

@@ -1059,6 +1059,12 @@ class FieldDeclaration extends MemberDeclaration, @field {
 
   /** Holds if this is a TypeScript field marked as definitely assigned with the `!` operator. */
   predicate hasDefiniteAssignmentAssertion() { hasDefiniteAssignmentAssertion(this) }
+
+  override predicate isAmbient() {
+    hasDeclareKeyword(this)
+    or
+    getParent().isAmbient()
+  }
 }
 
 /**

javascript/ql/src/semmlecode.javascript.dbscheme

@@ -200,8 +200,8 @@ case @stmt.kind of
 
 isInstantiated(unique int decl: @namespacedeclaration ref);
 
-@declarablestmt = @declstmt | @namespacedeclaration | @classdeclstmt | @functiondeclstmt | @enumdeclaration | @externalmoduledeclaration | @globalaugmentationdeclaration;
-hasDeclareKeyword(unique int stmt: @declarablestmt ref);
+@declarablenode = @declstmt | @namespacedeclaration | @classdeclstmt | @functiondeclstmt | @enumdeclaration | @externalmoduledeclaration | @globalaugmentationdeclaration | @field;
+hasDeclareKeyword(unique int stmt: @declarablenode ref);
 
 isForAwaitOf(unique int forof: @forofstmt ref);
 

javascript/ql/test/library-tests/TypeScript/DeclareInClass/test.expected

@@ -0,0 +1 @@
+| tst.ts:2:5:2:22 | declare x: number; | true |

javascript/ql/test/library-tests/TypeScript/DeclareInClass/test.ql

@@ -0,0 +1,5 @@
+import javascript
+
+from FieldDeclaration f, boolean ambient
+where if f.isAmbient() then ambient = true else ambient = false
+select f, ambient

javascript/ql/test/library-tests/TypeScript/DeclareInClass/tst.ts

@@ -0,0 +1,3 @@
+class C {
+    declare x: number;
+}