[cfe-dev] [EXT] [llvm-dev] Need template help building clang 3.4.2 on OpenVMS so we can bootstrap
John Reagan via cfe-dev
cfe-dev at lists.llvm.org
Thu Feb 28 09:01:57 PST 2019
Thanks. I'll play some more. I suspect our ancient EDG frontend has a
bug. I have a newer EDG drop but there is zero chance I could
cherry-pick the right set of fixes from the hundreds of changes between
the two.
As for cross-compiling, I've been thinking about that too. We were
hoping to get an Itanium-hosted cross-compiler like we have our legacy
C, BLISS, and Macro-32 compilers, but we don't need that for the OS
build/boot path. Our initial customer EAK is with Itanium-hosted
cross-compilers for the above mentioned and our other legacy frontends.
It is C++ that is the odd language out. I'll discuss with my team and
technical director.
We are using the AMD64 ABI with a few minor OpenVMS tweaks. I could
easily build a clang/LLVM 3.4.2 with those changes on Linux and then use
*that* compiler to build something, yank the objects over to an OpenVMS
x86 box (once available and stable), and then link them native. (Our
linker is also tolerant of non-OpenVMS objects too)
On 2/27/19 10:14 PM, Eli Friedman wrote:
> The way it's supposed to work is via template specialization; there's a declaration "struct isa_impl<To, ::clang::DeclContext>" at the bottom of DeclBase.h which is supposed to be used. Not sure why your compiler doesn't like it. Maybe it's instantiating the template before it sees the specialization? Or maybe it's failing to find the specialization when it instantiates the template? Not sure. I guess in that particular context, you could explicitly call Decl::castFromDeclContext, but I'm not sure how many other places would need to be fixed.
>
> Have you considered cross-compiling instead? That seems like less work than porting multiple versions of LLVM to OpenVMS.
>
> -Eli
>
> -----Original Message-----
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of John Reagan via llvm-dev
> Sent: Wednesday, February 27, 2019 1:06 PM
> To: cfe-dev at lists.llvm.org; via llvm-dev <llvm-dev at lists.llvm.org>
> Subject: [EXT] [llvm-dev] Need template help building clang 3.4.2 on OpenVMS so we can bootstrap
>
> Summary: I need some help building an older clang. I'm getting errors
> with casts inside of clang/include/clang/AST/DeclBase.h. I've hit the
> limit of my template programming knowledge (not that deep to begin with)
> and am looking for workarounds/suggestions. I'm not even sure if it is
> the Casting.h support itself or the usage of it inside clang's DeclBase.h
>
> Background: We're porting OpenVMS to x86 using LLVM. Our build
> environment is OpenVMS Itanium using an old EDG/Intel C++ compiler
> (allegedly C++03). I've been able to build LLVM 3.4.2 just fine (with
> only minor tweaks) and we're using that backend with our legacy
> frontends. I'm now needing to also build the matching clang 3.4.2 so I
> can start the bootstrapping process to get us to a newer version on our
> native systems.
>
> Should clang 3.4.2 be buildable by a C++03 compiler like LLVM is?
> That's my understanding. Or is it something in LLVM's Support/Casting.h
> that only clang exploits?
>
> Any template experts to help me resolve these just so we can bootstrap?
> We're looking to use clang/LLVM 3.4.2 to build 3.8.0 as the next step
> (we don't have CMake on OpenVMS Itanium due to old C++ compiler)
>
> Thanks for helping!
>
> John
>
>
> On my first build attempt (we have a bash shell, make, etc. on OpenVMS),
> I got errors compiling ParseAST.cpp. Including "incomplete type is not
> allowed" and "explicit specialization of class "..." must precede its
> first use. Which I resolved with adding an explicit #include
> "clang/AST/DeclBase.h" in ParseAST.cpp prior to the other #include's.
>
> Then that yielded
>
> return To::classof(&Val);
> ...............^
> %CXX-E-NOTMEMBER, class "clang::Decl" has no member "classof"
> detected during:
> instantiation of "bool llvm::iqsa_impl<To, From,
> Enabler>::doit(const From &) [with To=clang::Decl,
>
> From=llvm::remove_pointer<llvm::simplify_type<clang::Decl
> Context *const>::NonConstSimpleType>::type,
> Enabler=void]" at line 98 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_cl<To, const From
> *>::doit(const From *) [with To=clang::Decl,
>
> From=llvm::remove_pointer<llvm::simplify_type<clang::Decl
> Context *const>::NonConstSimpleType>::type]" at
> line 124
> of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_wrap<To, FromTy,
> FromTy>::doit(const FromTy &) [with To=clang::Decl,
> FromTy=llvm::simplify_type<clang::DeclContext
> *const>::SimpleType]" at line 114 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_wrap<To, From,
> SimpleFrom>::doit(const From &) [with To=clang::Decl,
> From=clang::DeclContext *const,
> SimpleFrom=llvm::simplify_type<clang::DeclContext
> *const>::SimpleType]" at line 135 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa<X,Y>(const Y &) [with
> X=clang::Decl, Y=clang::DeclContext *]" at line 239 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "llvm::cast_retty<X, Y *>::ret_type
> llvm::cast<X,Y>(Y *) [with X=clang::Decl,
> Y=clang::DeclContext]" at line 1064 of
>
> "LLVM$:[REAGAN.llvm-342.tools.clang.include.clang.AST]Dec
> lBase.h;1"
> at line number 55 in file
> LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1
>
> The offending source in DeclBase.h is
>
> /// getParent - Returns the containing DeclContext.
> DeclContext *getParent() {
> return cast<Decl>(this)->getDeclContext();
> -----------^^^^^^^^^^^^
> }
> const DeclContext *getParent() const {
> return const_cast<DeclContext*>(this)->getParent();
> }
>
> So I guessed (perhaps wrongly?) that my host compiler wanted to see a
> classof() for clang::Decl so I added this to DeclBase.h in Decl's public
> section which matches what is done for DeclContext's classof().
>
> static bool classof(const Decl *D) { return true; }
>
> but that ended up with:
>
> return To::classof(&Val);
> .......................^
> %CXX-E-INCOMPATIBLEPRM, argument of type "const
> llvm::remove_pointer<llvm::simplify_type<clang::DeclContext
> *const>::NonConstSimpleType>::type *" is incompatible with
> parameter
> of type "const clang::Decl *"
> detected during:
> instantiation of "bool llvm::isa_impl<To, From,
> Enabler>::doit(const From &) [with To=clang::Decl,
>
> From=llvm::remove_pointer<llvm::simplify_type<clang::Decl
> Context *const>::NonConstSimpleType>::type,
> Enabler=void]" at line 98 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_cl<To, const From
> *>::doit(const From *) [with To=clang::Decl,
>
> From=llvm::remove_pointer<llvm::simplify_type<clang::Decl
> Context *const>::NonConstSimpleType>::type]" at
> line 124
> of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_wrap<To, FromTy,
> FromTy>::doit(const FromTy &) [with To=clang::Decl,
> FromTy=llvm::simplify_type<clang::DeclContext
> *const>::SimpleType]" at line 114 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa_impl_wrap<To, From,
> SimpleFrom>::doit(const From &) [with To=clang::Decl,
> From=clang::DeclContext *const,
> SimpleFrom=llvm::simplify_type<clang::DeclContext
> *const>::SimpleType]" at line 135 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "bool llvm::isa<X,Y>(const Y &) [with
> X=clang::Decl, Y=clang::DeclContext *]" at line 239 of
>
> "LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1"
> instantiation of "llvm::cast_retty<X, Y *>::ret_type
> llvm::cast<X,Y>(Y *) [with X=clang::Decl,
> Y=clang::DeclContext]" at line 1073 of
>
> "LLVM$:[REAGAN.llvm-342.tools.clang.include.clang.AST]Dec
> lBase.h;2"
> at line number 55 in file
> LLVM$:[REAGAN.llvm-342.include.llvm.Support]Casting.h;1
>
> and still lots of other errors of the form
>
> LEAF_TYPE(Enum)
> ^
> %CXX-E-NOCONVERSIONFUN, no suitable conversion function from
> "const clang::EnumType" to "const clang::EnumType *" exists
> at line number 115 in file
> LLVM$:[REAGAN.llvm-342.tools.clang.include.clang.AST]TypeNodes.def;1
>
> and more "incomplete type is not allowed" errors.
>
> And why is there very different form of non-const vs const for things
> like getParent() and getLexicalParent()?
>
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