Add an opt-in mechanism for non-differentiable types. - #1930
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| /// declaration -- non-differentiable, by specializing clad::Tag for it. Use at | ||
| /// global scope. The type may contain commas, e.g. | ||
| /// CLAD_NONDIFFERENTIABLE_TYPE(std::map<int, double>); | ||
| #define CLAD_NONDIFFERENTIABLE_TYPE(...) \ |
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warning: variadic macro 'CLAD_NONDIFFERENTIABLE_TYPE' used; consider using a 'constexpr' variadic template function [cppcoreguidelines-macro-usage]
#define CLAD_NONDIFFERENTIABLE_TYPE(...) \
^| class CLAD_NONDIFFERENTIABLE Tag<::std::basic_streambuf<C, Tr>> {}; | ||
| template <class C, class Tr> | ||
| class CLAD_NONDIFFERENTIABLE Tag<::std::basic_ios<C, Tr>> {}; | ||
| template <> class CLAD_NONDIFFERENTIABLE Tag<::std::ios_base> {}; |
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warning: no header providing "std::ios_base" is directly included [misc-include-cleaner]
include/clad/Differentiator/STLBuiltins.h:9:
- #include <iosfwd>
+ #include <ios>
+ #include <iosfwd>| // The value-level macro marks a single type; a template instantiation is | ||
| // only that specialization. Marking the whole family needs a clad::Tag | ||
| // partial specialization the macro cannot express. | ||
| if (isa<clang::ClassTemplateSpecializationDecl>(RD)) |
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warning: no header providing "clang::ClassTemplateSpecializationDecl" is directly included [misc-include-cleaner]
lib/Differentiator/DerivativeBuilder.cpp:52:
- #include <cstddef>
+ #include <clang/AST/DeclTemplate.h>
+ #include <cstddef>
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When clad has no custom derivative for a called function it synthesizes one by cloning the function's body. For a type whose internals are not meant to be differentiated -- a standard-library primitive, an I/O stream -- that clone is at best wasteful and at worst ill-formed: cloning std::string's char-pointer constructor emits a static reverse-forward propagator that dereferences a null `this` and crashes CodeGen. A type is now non-differentiable when it carries the `non_differentiable` annotation -- on the type itself for code the user owns (CLAD_NONDIFFERENTIABLE), or on a clad::Tag<T> specialization for a foreign type the user cannot annotate at its declaration (CLAD_NONDIFFERENTIABLE_TYPE). utils::isNonDifferentiableType detects it, so clad never clones such a type's constructor or member bodies, and callOperatesOnNonDifferentiableType extends the treatment to a call whose object is opaque (e.g. a std::ostream operation). Seed std::string, std::allocator and the stream family in STLBuiltins.h. -fclad-porting-hints prints the paste-able CLAD_NONDIFFERENTIABLE_TYPE spelling and, for a reverse-forward pass, the elidable_reverse_forw route with its signature -- pointing at existing mechanisms rather than inventing new ones. isElidableConstructor is renamed to constructorReverseForwIsElidable and documented so its "a trivial copy is a shallow share" coverage is discoverable; that made a separate data-less-copy heuristic unnecessary. The user guide documents both macros; tests cover marker-based construction opacity (StringConstructor) and a marked-type call (NonDifferentiableMarkedType).
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When clad has no custom derivative for a called function it synthesizes one by cloning the function's body. For a type whose internals are not meant to be differentiated -- a standard-library primitive, an I/O stream -- that clone is at best wasteful and at worst ill-formed: cloning std::string's char-pointer constructor emits a static reverse-forward propagator that dereferences a null
thisand crashes CodeGen.A type is now non-differentiable when it carries the
non_differentiableannotation -- on the type itself for code the user owns (CLAD_NONDIFFERENTIABLE), or on a clad::Tag specialization for a foreign type the user cannot annotate at its declaration (CLAD_NONDIFFERENTIABLE_TYPE). utils::isNonDifferentiableType detects it, so clad never clones such a type's constructor or member bodies, and callOperatesOnNonDifferentiableType extends the treatment to a call whose object is opaque (e.g. a std::ostream operation). Seed std::string, std::allocator and the stream family in STLBuiltins.h.-fclad-porting-hints prints the paste-able CLAD_NONDIFFERENTIABLE_TYPE spelling and, for a reverse-forward pass, the elidable_reverse_forw route with its signature -- pointing at existing mechanisms rather than inventing new ones. isElidableConstructor is renamed to constructorReverseForwIsElidable and documented so its "a trivial copy is a shallow share" coverage is discoverable; that made a separate data-less-copy heuristic unnecessary.
The user guide documents both macros; tests cover marker-based construction opacity (StringConstructor) and a marked-type call (NonDifferentiableMarkedType).