1216630 - Print class source when calling toString on the constructor.

This is accomplished in the following ways.
LazyScripts and JSScripts now have 4 offsets:
- Source begin and end for the actual source. This is used for lazy parsing.

- toString begin and end for toString. Some kinds of functions, like async, only have a different begin offset. Class constructors have different offsets for both begin and end.

For syntactically present (i.e. non-default) constructors, the class source span is remembered directly on the LazyScript or JSScript. The toString implementation then splices out the substring directly. For default constructors, a new SRC_CLASS SrcNote type is added. It's binary and has as its arguments the begin and end offsets of the class expression or statement. MakeDefaultConstructor reads the note and overrides the cloned self-hosted function's source object. This is probably the least intrusive way to accomplish this.

1 files changed, 11 insertions, 0 deletions

diff --git a/js/src/frontend/SharedContext.h b/js/src/frontend/SharedContext.h
index f5a74e18c..213a0a461 100644
--- a/js/src/frontend/SharedContext.h
+++ b/js/src/frontend/SharedContext.h
@@ -38,6 +38,7 @@ enum class StatementKind : uint8_t
     ForOfLoop,
     DoLoop,
     WhileLoop,
+    Class,
 
     // Used only by BytecodeEmitter.
     Spread
@@ -451,6 +452,7 @@ class FunctionBox : public ObjectBox, public SharedContext
     uint32_t        startLine;
     uint32_t        startColumn;
     uint32_t        preludeStart;
+    uint32_t        postludeEnd;
     uint16_t        length;
 
     uint8_t         generatorKindBits_;     /* The GeneratorKind of this function. */
@@ -501,6 +503,7 @@ class FunctionBox : public ObjectBox, public SharedContext
     void initFromLazyFunction();
     void initStandaloneFunction(Scope* enclosingScope);
     void initWithEnclosingParseContext(ParseContext* enclosing, FunctionSyntaxKind kind);
+    void resetForAbortedSyntaxParse(ParseContext* enclosing, FunctionSyntaxKind kind);
 
     ObjectBox* toObjectBox() override { return this; }
     JSFunction* function() const { return &object->as<JSFunction>(); }
@@ -603,6 +606,14 @@ class FunctionBox : public ObjectBox, public SharedContext
         tokenStream.srcCoords.lineNumAndColumnIndex(bufStart, &startLine, &startColumn);
     }
 
+    void setEnd(uint32_t end) {
+        // For all functions except class constructors, the buffer and
+        // postlude ending positions are the same. Class constructors override
+        // the postlude ending position with the end of the class definition.
+        bufEnd = end;
+        postludeEnd = end;
+    }
+
     void trace(JSTracer* trc) override;
 };