Infer whether a variable is assigned

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 19 matching lines @@
 #include <string.h>
 
 #include "src/v8.h"
 
 #include "src/compiler.h"
 #include "src/execution.h"
 #include "src/isolate.h"
 #include "src/objects.h"
 #include "src/parser.h"
 #include "src/preparser.h"
+#include "src/rewriter.h"
 #include "src/scanner-character-streams.h"
 #include "src/token.h"
 #include "src/utils.h"
 #include "test/cctest/cctest.h"
 
 TEST(ScanKeywords) {
   struct KeywordToken {
     const char* keyword;
     i::Token::Value token;
   };
@@ skipping 2492 matching lines @@
   v8::Local<v8::String> source =
       v8::String::NewFromTwoByte(isolate, two_byte_source);
   v8::Local<v8::Value> result = CompileRun(source);
   CHECK(result->IsString());
   v8::Local<v8::String> expected_name =
       v8::String::NewFromTwoByte(isolate, two_byte_name);
   CHECK(result->Equals(expected_name));
   i::DeleteArray(two_byte_source);
   i::DeleteArray(two_byte_name);
 }
+
+
+TEST(InnerAssignment) {
+  i::Isolate* isolate = CcTest::i_isolate();
+  i::Factory* factory = isolate->factory();
+  i::HandleScope scope(isolate);
+  LocalContext env;
+
+  const char* prefix = "function f() {";
+  const char* midfix = " function g() {";
+  const char* suffix = "}}";
+  struct { const char* source; bool assigned; bool strict; } outers[] = {
+    // Actual assignments.
+    { "var x; var x = 5;", true, false },
+    { "var x; { var x = 5; }", true, false },
+    { "'use strict'; let x; x = 6;", true, true },
+    // Actual non-assignments.
+    { "var x;", false, false },
+    { "var x = 5;", false, false },
+    { "'use strict'; let x;", false, true },
+    { "'use strict'; let x = 6;", false, true },
+    { "'use strict'; var x = 0; { let x = 6; }", false, true },
+    { "'use strict'; var x = 0; { let x; x = 6; }", false, true },
+    { "'use strict'; let x = 0; { let x = 6; }", false, true },
+    { "'use strict'; let x = 0; { let x; x = 6; }", false, true },
+    { "var x; try {} catch (x) { x = 5; }", false, false },
+    { "function x() {}", false, false },
+    // Eval approximation.
+    { "var x; eval('');", true, false },
+    { "eval(''); var x;", true, false },
+    { "'use strict'; let x; eval('');", true, true },
+    { "'use strict'; eval(''); let x;", true, true },
+    // Non-assignments not recognized, because the analysis is approximative.
+    { "var x; var x;", true, false },
+    { "var x = 5; var x;", true, false },
+    { "var x; { var x; }", true, false },
+    { "var x; function x() {}", true, false },
+    { "function x() {}; var x;", true, false },
+    { "var x; try {} catch (x) { var x = 5; }", true, false },
+  };
+  struct { const char* source; bool assigned; bool with; } inners[] = {
+    // Actual assignments.
+    { "x = 1;", true, false },
+    { "x++;", true, false },
+    { "++x;", true, false },
+    { "x--;", true, false },
+    { "--x;", true, false },
+    { "{ x = 1; }", true, false },
+    { "'use strict'; { let x; }; x = 0;", true, false },
+    { "'use strict'; { const x = 1; }; x = 0;", true, false },
+    { "'use strict'; { function x() {} }; x = 0;", true, false },
+    { "with ({}) { x = 1; }", true, true },
+    { "eval('');", true, false },
+    { "'use strict'; { let y; eval('') }", true, false },
+    { "function h() { x = 0; }", true, false },
+    { "(function() { x = 0; })", true, false },
+    { "(function() { x = 0; })", true, false },
+    { "with ({}) (function() { x = 0; })", true, true },
+    // Actual non-assignments.
+    { "", false, false },
+    { "x;", false, false },
+    { "var x;", false, false },
+    { "var x = 8;", false, false },
+    { "var x; x = 8;", false, false },
+    { "'use strict'; let x;", false, false },
+    { "'use strict'; let x = 8;", false, false },
+    { "'use strict'; let x; x = 8;", false, false },
+    { "'use strict'; const x = 8;", false, false },
+    { "function x() {}", false, false },
+    { "function x() { x = 0; }", false, false },
+    { "function h(x) { x = 0; }", false, false },
+    { "'use strict'; { let x; x = 0; }", false, false },
+    { "{ var x; }; x = 0;", false, false },
+    { "with ({}) {}", false, true },
+    { "var x; { with ({}) { x = 1; } }", false, true },
+    { "try {} catch(x) { x = 0; }", false, false },
+    { "try {} catch(x) { with ({}) { x = 1; } }", false, true },
+    // Eval approximation.
+    { "eval('');", true, false },
+    { "function h() { eval(''); }", true, false },
+    { "(function() { eval(''); })", true, false },
+    // Shadowing not recognized because of eval approximation.
+    { "var x; eval('');", true, false },
+    { "'use strict'; let x; eval('');", true, false },
+    { "try {} catch(x) { eval(''); }", true, false },
+    { "function x() { eval(''); }", true, false },
+    { "(function(x) { eval(''); })", true, false },
+  };
+  i::Handle<i::String> var_name = factory->InternalizeUtf8String("x");
+
+  int prefix_len = Utf8LengthHelper(prefix);
+  int midfix_len = Utf8LengthHelper(midfix);
+  int suffix_len = Utf8LengthHelper(suffix);
+  for (unsigned i = 0; i < ARRAY_SIZE(outers); ++i) {
+    const char* outer = outers[i].source;
+    int outer_len = Utf8LengthHelper(outer);
+    for (unsigned j = 0; j < ARRAY_SIZE(inners); ++j) {
+      if (outers[i].strict && inners[j].with) continue;
+      const char* inner = inners[j].source;
+      int inner_len = Utf8LengthHelper(inner);
+      int len = prefix_len + outer_len + midfix_len + inner_len + suffix_len;
+      i::ScopedVector<char> program(len + 1);
+      i::SNPrintF(program, "%s%s%s%s%s", prefix, outer, midfix, inner, suffix);
+      i::Handle<i::String> source =
+          factory->InternalizeUtf8String(program.start());
+      source->PrintOn(stdout);
+      printf("\n");
+
+      i::Handle<i::Script> script = factory->NewScript(source);
+      i::CompilationInfoWithZone info(script);
+      i::Parser parser(&info);
+      parser.set_allow_harmony_scoping(true);
+      CHECK(parser.Parse());
+      CHECK(i::Rewriter::Rewrite(&info));
+      CHECK(i::Scope::Analyze(&info));
+      CHECK(info.function() != NULL);
+
+      i::Scope* scope = info.function()->scope();
+      CHECK_EQ(scope->inner_scopes()->length(), 1);
+      i::Scope* inner_scope = scope->inner_scopes()->at(0);
+      i::Variable* var = inner_scope->Lookup(var_name);
+      bool expected = outers[i].assigned || inners[j].assigned;
+      CHECK(var != NULL);
+      CHECK(var->is_used() || !expected);
+      CHECK(var->maybe_assigned() == expected);
+    }
+  }
+}