Bug 53760 – JSC fails to build with TOT Clang

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Cameron Zwarich (cpst)]

Building JSC gives the following error (amongst others):

CompileC /Volumes/Data/symroots/JavaScriptCore.build/Debug/JavaScriptCore.build/Objects-normal/x86_64/Arguments.o runtime/Arguments.cpp normal x86_64 c++ com.apple.compilers.gcc.4_2
    cd /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore
    setenv LANG en_US.US-ASCII
    /Developer/usr/bin/gcc-4.2 -x c++ -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fno-exceptions -fno-rtti -fpascal-strings -fasm-blocks -O0 -Werror -Wmissing-prototypes -Wnon-virtual-dtor -Wnewline-eof -DHAVE_DTRACE=1 -DWEBKIT_VERSION_MIN_REQUIRED=WEBKIT_VERSION_LATEST -DHAVE_HEADER_DETECTION_H -fstrict-aliasing -fvisibility-inlines-hidden -fno-threadsafe-statics -mmacosx-version-min=10.6 -gdwarf-2 -I/Volumes/Data/symroots/JavaScriptCore.build/Debug/JavaScriptCore.build/JavaScriptCore.hmap -Wall -Wextra -Wcast-qual -Wchar-subscripts -Wextra-tokens -Wformat=2 -Winit-self -Wmissing-format-attribute -Wmissing-noreturn -Wpacked -Wpointer-arith -Wredundant-decls -Wundef -Wwrite-strings -F/Volumes/Data/symroots/Debug -I/Volumes/Data/symroots/Debug/include -I/Volumes/Data/symroots/Debug/DerivedSources/JavaScriptCore -I. -Iicu -I/Volumes/Data/symroots/JavaScriptCore.build/Debug/JavaScriptCore.build/DerivedSources/x86_64 -I/Volumes/Data/symroots/JavaScriptCore.build/Debug/JavaScriptCore.build/DerivedSources -include /var/folders/1t/1tFPZz2zFG8060hthPyLrk+++TI/-Caches-/com.apple.Xcode.501/SharedPrecompiledHeaders/JavaScriptCorePrefix-auvrpfrvjgzoucgqyebkkitidjdk/JavaScriptCorePrefix.h -c /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Arguments.cpp -o /Volumes/Data/symroots/JavaScriptCore.build/Debug/JavaScriptCore.build/Objects-normal/x86_64/Arguments.o

In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Arguments.cpp:26:
/Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Arguments.h:110:22: error: 'JSC::Arguments::put' hides overloaded virtual function [-Woverloaded-virtual]
        virtual void put(ExecState*, unsigned propertyName, JSValue, PutPropertySlot&);
                     ^
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Arguments.cpp:26:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Arguments.h:27:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/JSActivation.h:32:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/bytecode/CodeBlock.h:33:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/bytecode/EvalCodeCache.h:32:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/Executable.h:30:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/JSFunction.h:27:
In file included from /Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/JSObjectWithGlobalObject.h:29:
/Volumes/Data/WebKit-OpenSource/Source/JavaScriptCore/runtime/JSObject.h:113:22: note: hidden overloaded virtual function 'JSC::JSObject::put' declared here
        virtual void put(ExecState*, unsigned propertyName, JSValue value);
                     ^
1 error generated.

We use the idiom of adding new variants of an overloaded virtual function in derived classes throughout JSC, mostly with put() and getOwnProperty() functions. Perhaps we should give the overloaded versions a different name so we can keep the otherwise useful warning enabled?

[Geoffrey Garen]

I thin in most cases we can get rid of the custom overload. For example, in the arguments case, I don't think there's any reason to take a PutPropertySlot argument.

[Cameron Zwarich (cpst)]

I've got a patch that gets rid of the custom overloads in JSC. I just need to do more testing.

[Cameron Zwarich (cpst)]

Created attachment 82255 [details]
Proposed patch

[Cameron Zwarich (cpst)]

Landed in r78428. I'm building a new Clang to see if nothing else has been introduced before closing this.

[Cameron Zwarich (cpst)]

Verified that JSC builds with Clang r125450.