Fix deferred init narrowing #1446#1449
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…ler context. Use construct_from(lambda) so constexpr initializers are not lost across a call boundary, matching immediate initialization behavior. Note, change out::construct to use brace-init in all paths to be consistent and to align with deferred init. Add regression tests for literals (negative too), constexpr, aggregates. Update snapshots affected by the change.
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| construct_from([&]() -> T { return T{CPP2_FORWARD(args)...}; }); | ||
| } | ||
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| constexpr auto construct_from(auto&& factory) -> void |
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With the factory, all the values are still on the caller context, which means their constexpr-ness isn't lost during crossing the call boundaries.
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| if constexpr (requires { *t = CPP2_FORWARD(factory)(); }) { | ||
| cpp2_default.enforce( t ); | ||
| *t = T(CPP2_FORWARD(args)...); | ||
| *t = CPP2_FORWARD(factory)(); |
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Here, instead of parens-init we switched to braces-init to align with deferred init, which is also used in out down below.
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| y0.construct(sqrt(x0)); | ||
| y.construct(CPP2_UFCS(sqrt)(x, x0)); | ||
| y0.construct_from([&]() -> typename CPP2_TYPEOF(y0)::value_type { return typename CPP2_TYPEOF(y0)::value_type{sqrt(x0)}; }); | ||
| y.construct_from([&]() -> typename CPP2_TYPEOF(y)::value_type { return typename CPP2_TYPEOF(y)::value_type{CPP2_UFCS(sqrt)(x, x0)}; }); |
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We could introduce a macro for this. If we decide to, I can bring it in this PR.
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Jul 17, 2026
| @@ -0,0 +1,57 @@ | |||
| pure2-bugfix-for-deferred-init-narrowing-matrix-error.cpp2:19:125: error: non-constant-expression cannot be narrowed from type 'cpp2::impl::in<cpp2::i16>' (aka 'const short') to 'signed char' in initializer list [-Wc++11-narrowing] | |||
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This tests errors, i.e. failing cases, when we do want the compilation to fail.
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Fix deferred init narrowing #1446 by keeping brace-init in caller context.