AuroraMiddleware/v8
1
0
Fork 0
Code Issues 2 Pull Requests Releases Wiki Activity

Prevent calls to ReturnValue::Set with pointer-valued types.

Browse Source 
[2nd try, after the previous version broke the build]

Currently, this code will compile:
SomePointer* p = ...;
ReturnValue r = ...;
r.Set(p);

What happens is that ReturnValue::Set has no pointer-ish overloads, but
a bool one, and hence C++ will convert the pointer to a bool and use
the Set(bool) overload. In other words, the example above is equivalent
to: r.Set(p ? true : false); Which probably isn't what the author had
in mind. This change adds a Set(void*) overload whose body forces a
compile error, to prevent this from happening inadvertently. The only
use of this indeed turned out to be an error.

(Said error was fixed/removed in crrev.com/267393002.)

Why was crrev.com/240013004 reverted?
The orginal version compiled fine on gcc (+ MSVC), but not on clang.
There's no clang try-bots, but the ASAN-based buildbots used clang
and hence the build broke. I'm slightly unsure on why, but clang -
unlike those other compilers - eagerly compiled the non-compilable
setter, which predictably broke. Now, the non-compilable setter uses
the same template logic that all other, comparable cases use. I've
tried 'make qc' with both gcc and clang versions.

BUG=
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/279883002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21228 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
vogelheim@chromium.org 2014-05-09 15:36:51 +00:00
parent cb1a32885c
commit 623f2371eb
1 changed files with 11 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/v8.h
View File

@ -2429,6 +2429,10 @@ class ReturnValue {
// Convenience getter for Isolate
V8_INLINE Isolate* GetIsolate();
// Pointer setter: Uncompilable to prevent inadvertent misuse.
template <typename S>
V8_INLINE void Set(S* whatever);
private:
template<class F> friend class ReturnValue;
template<class F> friend class FunctionCallbackInfo;
@ -5973,6 +5977,13 @@ Isolate* ReturnValue<T>::GetIsolate() {
return *reinterpret_cast<Isolate**>(&value_[-2]);
}
template<typename T>
template<typename S>
void ReturnValue<T>::Set(S* whatever) {
// Uncompilable to prevent inadvertent misuse.
TYPE_CHECK(S*, Primitive);
}
template<typename T>
internal::Object* ReturnValue<T>::GetDefaultValue() {
// Default value is always the pointer below value_ on the stack.