ymandel added a comment. In D139544#3982821 <https://reviews.llvm.org/D139544#3982821>, @isuckatcs wrote:
>> the temporary's construction should appear before, but the binding decls, >> which use the synthetic variables, should appear after > > I'm confused a bit here. Right now the CFG looks like this: > > <constructor_call> > <binding_decl_0> > ... > <binding_decl_n> > > Based on what you say I assume you want something to happen between > `constructor_call` and `binding_decl_0`. > Could you visualize somehow how you think the ideal CFG here looks like? Sorry, I should have explained in more detail (refernce example: https://godbolt.org/z/dE9ojcjj7). *Perhaps I'm still misreading the CFG, but I don't see the binding decls serialized in the CFG, only the synthesized var decls.* That is, here's my reading of the CFG: The resulting simplified CFG would be: <constructor_call> <synthesized_var_decl_0> ... <synthesized_var_decl_n> In more detail, here is my annotated reading of the CFG, based on our discussion: [B1] 1: mk 2: [B1.1] (ImplicitCastExpr, FunctionToPointerDecay, std::tuple<int, int> (*)(void)) 3: [B1.2]() (CXXRecordTypedCall, [B1.4]) 4: auto = mk(); // <constructor_call> (with <binding_decl_0>, <binding_decl_1> nested as children) 5: get<0UL> 6: [B1.5] (ImplicitCastExpr, FunctionToPointerDecay, typename tuple_element<0, tuple<int, int> >::type (*)(tuple<int, int>)) 7: // <ref to anonymous temporary defined on line 4> 8: [B1.7] (ImplicitCastExpr, NoOp, std::tuple<int, int>) 9: [B1.8] (CXXConstructExpr, [B1.10]+0, tuple<int, int>) 10: [B1.6]([B1.9]) 11: [B1.10] 12: std::tuple_element<0, std::tuple<int, int>>::type i0 = get<0UL>(); // <synth_var_decl_0> 13: get<1UL> 14: [B1.13] (ImplicitCastExpr, FunctionToPointerDecay, typename tuple_element<1, tuple<int, int> >::type (*)(tuple<int, int>)) 15: // <ref to anonymous temporary defined on line 4> 16: [B1.15] (ImplicitCastExpr, NoOp, std::tuple<int, int>) 17: [B1.16] (CXXConstructExpr, [B1.18]+0, tuple<int, int>) 18: [B1.14]([B1.17]) 19: [B1.18] 20: std::tuple_element<1, std::tuple<int, int>>::type i1 = get<1UL>(); // <synth_var_decl_1> 21: i0 // ref to <binding_decl_0> 22: (void)[B1.21] (CStyleCastExpr, ToVoid, void) Here is the crux of the issue: per the AST, line 21 is reference is to the *`BindingDecl`*, not the (synthesized) `VarDecl`: -DeclRefExpr <col:9> 'std::tuple_element<0, std::tuple<int, int>>::type':'int' lvalue Binding 0x559942acf350 'i0' 'std::tuple_element<0, std::tuple<int, int>>::type':'int' So, in order to make sense of that reference, I need to define the `BindingDecl`. But, that in turn is defined in terms of the (synthesized) `VarDecl`. So, I want to insert between elements 20 and 21: 20.a: <binding_decl_0> // references synthesized variable `i0` from line 12 in its binding 20.b: <binding_decl_1> // references synthesized variable `i1` from line 20 in its binding The resulting simplified CFG would be: <constructor_call> <synthesized_var_decl_0> ... <synthesized_var_decl_n> <binding_decl_0> ... <binding_decl_n> I suggested repeating the `DecompositionDecl` because it includes the `BindingDecls`, but spelling them out explicitly would probably be even better. Right now, the only chance I get to visit the `BindingDecls` is when I encounter line 4, as children of the `DecompositionDecl`, at which point the `binding` of each decl reference as-yet-undefined (synthesized) `VarDecl`s, hence my dilemma. I'm fine with a custom solution -- that's indeed what this patch contains and I'm happy to leave it at that. Thank you, again, for your patience hashing this out! Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D139544/new/ https://reviews.llvm.org/D139544 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
