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hsutterhsutter
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Add UFCS failure case error diagnostics (#1023)
* Add UFCS failure case error diagnostics * Restore UFCS SFINAE test to just _NONLOCAL versions Per #1023 (comment) and followups
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‎include/cpp2util.h

Lines changed: 37 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -27,7 +27,7 @@
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// 2) Entities in namespace cpp2::impl::, and macros
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//
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// These should not be used by the program. They form the language
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// support library intended to be called only from generated Cpp2 code.
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// support library intended to be called only from generated code.
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//
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// For example, if a Cpp2 function leaves a local variable
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// uninitialized, cppfront will generate uses of impl::deferred_init<>
@@ -887,6 +887,7 @@ class out {
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#endif
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#endif
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#define CPP2_UFCS_EMPTY(...)
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#define CPP2_UFCS_IDENTITY(...) __VA_ARGS__
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#define CPP2_UFCS_REMPARENS(...) __VA_ARGS__
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@@ -937,30 +938,49 @@ class out {
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#define CPP2_UFCS_CONSTRAINT_ARG(...) IsViable
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#endif
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#define CPP2_UFCS_(LAMBDADEFCAPT,MVFWD,QUALID,TEMPKW,...) \
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template <class T> struct dependent_false : std::false_type {};
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#define CPP2_UFCS_(LAMBDADEFCAPT,SFINAE,MVFWD,QUALID,TEMPKW,...) \
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[LAMBDADEFCAPT]< \
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typename Obj, typename... Params \
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CPP2_UFCS_IS_NOTHROW_PARAM(MVFWD,QUALID,TEMPKW,__VA_ARGS__) \
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CPP2_UFCS_CONSTRAINT_PARAM(MVFWD,QUALID,TEMPKW,__VA_ARGS__) \
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> \
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CPP2_LAMBDA_NO_DISCARD (Obj&& obj, Params&& ...params) CPP2_FORCE_INLINE_LAMBDA_CLANG \
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noexcept(CPP2_UFCS_IS_NOTHROW_ARG(MVFWD,QUALID,TEMPKW,__VA_ARGS__)) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
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requires CPP2_UFCS_CONSTRAINT_ARG(MVFWD,QUALID,TEMPKW,__VA_ARGS__) { \
949-
if constexpr (requires{ CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); }) { \
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return CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); \
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} else { \
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return MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
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SFINAE( requires CPP2_UFCS_CONSTRAINT_ARG(MVFWD,QUALID,TEMPKW,__VA_ARGS__) ) \
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{ \
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if constexpr (requires{ CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); }) { \
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return CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); \
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} \
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}
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#define CPP2_UFCS(...) CPP2_UFCS_(&,CPP2_UFCS_IDENTITY,(),,__VA_ARGS__)
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#define CPP2_UFCS_MOVE(...) CPP2_UFCS_(&,std::move,(),,__VA_ARGS__)
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#define CPP2_UFCS_FORWARD(...) CPP2_UFCS_(&,CPP2_FORWARD,(),,__VA_ARGS__)
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#define CPP2_UFCS_TEMPLATE(...) CPP2_UFCS_(&,CPP2_UFCS_IDENTITY,(),template,__VA_ARGS__)
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#define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...) CPP2_UFCS_(&,CPP2_UFCS_IDENTITY,QUALID,template,__VA_ARGS__)
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#define CPP2_UFCS_NONLOCAL(...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,(),,__VA_ARGS__)
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#define CPP2_UFCS_TEMPLATE_NONLOCAL(...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,(),template,__VA_ARGS__)
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#define CPP2_UFCS_QUALIFIED_TEMPLATE_NONLOCAL(QUALID,...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,QUALID,template,__VA_ARGS__)
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else if constexpr (requires{ MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); }) { \
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return MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
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} \
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else if constexpr (requires{ obj.CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); }) { \
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static_assert( cpp2::impl::dependent_false<Obj>::value, "this function call syntax tries 'obj.func(...)', then 'func(obj,...);' - both failed, but the first would have succeeded if obj were an lvalue - the likely problem is that this is a definite last use of the object (which automatically treats it as an rvalue / move candidate), and the function cannot accept an rvalue" ); \
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CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); \
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MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
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} \
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else if constexpr (requires{ MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(obj, CPP2_FORWARD(params)...); }) { \
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static_assert( cpp2::impl::dependent_false<Obj>::value, "this function call syntax tries 'obj.func(...)', then 'func(obj,...);' - both failed, but the second would have succeeded if obj were an lvalue - the likely problem is that this is a definite last use of the object, (which automatically treats it as an rvalue / move candidate) and the function cannot accept an rvalue" ); \
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CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); \
967+
MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
968+
} \
969+
else { \
970+
static_assert( cpp2::impl::dependent_false<Obj>::value, "this function call syntax tries 'obj.func(...)', then 'func(obj,...);' - both failed, did you spell the function name correctly?" ); \
971+
CPP2_FORWARD(obj).CPP2_UFCS_REMPARENS QUALID TEMPKW __VA_ARGS__(CPP2_FORWARD(params)...); \
972+
MVFWD(CPP2_UFCS_REMPARENS QUALID __VA_ARGS__)(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
973+
} \
974+
}
975+
976+
#define CPP2_UFCS(...) CPP2_UFCS_(&,CPP2_UFCS_EMPTY,CPP2_UFCS_IDENTITY,(),,__VA_ARGS__)
977+
#define CPP2_UFCS_MOVE(...) CPP2_UFCS_(&,CPP2_UFCS_EMPTY,std::move,(),,__VA_ARGS__)
978+
#define CPP2_UFCS_FORWARD(...) CPP2_UFCS_(&,CPP2_UFCS_EMPTY,CPP2_FORWARD,(),,__VA_ARGS__)
979+
#define CPP2_UFCS_TEMPLATE(...) CPP2_UFCS_(&,CPP2_UFCS_EMPTY,CPP2_UFCS_IDENTITY,(),template,__VA_ARGS__)
980+
#define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...) CPP2_UFCS_(&,CPP2_UFCS_EMPTY,CPP2_UFCS_IDENTITY,QUALID,template,__VA_ARGS__)
981+
#define CPP2_UFCS_NONLOCAL(...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,CPP2_UFCS_IDENTITY,(),,__VA_ARGS__)
982+
#define CPP2_UFCS_TEMPLATE_NONLOCAL(...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,CPP2_UFCS_IDENTITY,(),template,__VA_ARGS__)
983+
#define CPP2_UFCS_QUALIFIED_TEMPLATE_NONLOCAL(QUALID,...) CPP2_UFCS_(,CPP2_UFCS_IDENTITY,CPP2_UFCS_IDENTITY,QUALID,template,__VA_ARGS__)
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} // impl
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