Type-based APIs become an explicit non-goal, and say so (DAP056) - #214
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mgravell wants to merge 2 commits into
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Type-based APIs become an explicit non-goal, and say so (DAP056)#214mgravell wants to merge 2 commits into
mgravell wants to merge 2 commits into
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#212 made "what does Dapper.AOT do with this overload?" a derived fact, so this stops the table answering it from memory. ApiSurface.expected.txt is named as the source of truth, with the three things it deliberately does not cover - behaviour, per-call-site refusals, and non-extension statics like Format and LookupDbType, which are called rather than intercepted. Three ❓ rows are settled by the report and now cite it: Parse (all three overloads sit outside the generator's name filter), Format/ReplaceLiterals (same, and Format is not even an extension method), and CommandDefinition - which was the worst of the stale rows. It read as an unverified question about CommandFlags.Pipelined; it is in fact 27 overloads, every one skipped in silence, which is high impact rather than the "med" it carried. Split into the overload row and a separate CommandFlags row, since the second is moot until the first is fixed. The delta summary now leads with both measurements rather than one, because they answer different questions: 40 of 110 overloads tell the consumer nothing, and 677 of 793 corpus tests pass. Adds a row 0 - saying *something* at those 40 - as the cheapest item on the list: it supports no new API, and turns a silent runtime AOT failure into a build warning. Remaining ❓ now means "needs a corpus run" unless a row says otherwise.
Decided 2026-08-26. Dapper's Type-argument overloads pick the row type at execution time, which is the one thing compile-time generation cannot follow. Supporting them means a build-time registry of candidate types plus runtime dispatch keyed on Type - a lookup on the hot path, an open world for the trimmer, and dispatch ILC cannot resolve unless every announced type is rooted. That is the shape #206 was closed over; rebuilding it for a lower-value feature would be incoherent. Costs no behaviour: these already generated nothing (a five-call probe handled 0 of 5). What changes is what we say. DAP056 fires at the call-site and names the generic overload, replacing either silence or a confusing DAP009 about an unexpected 'type' parameter. Detection is call-site sensitive, not symbol-level, because GetRowParser<T>(concreteType: null) - the default, and the common case - is perfectly supportable. Only a call that actually passes a Type defers the decision. GetRowParser<T>() stays supported and the fixture pins both halves. GetRowParser(concreteType) goes too, on Marc's call. It is the one row where "use the generic form" is not available advice - the choice is data-dependent - so the rule doc gives the pattern that is actually correct under AOT: a switch over GetRowParser<T>() per candidate, which roots exactly the types used rather than everything registered. Reported from the generator rather than the analyzer: most of these overloads carry no `sql` string, so the analyzer never sees them. SkippedSourceState gains a reason enum (plain data, so the cached model stays equatable) and Generate emits from it. Knock-on: the surface report grows a 'non-goal: Type-based' bucket for overloads whose Type parameter is required, so the silent count drops 27 -> 22 and undiagnosed-unsupported 13 -> 12. GetRowParser's fixture goes from 1 silent skip to 0. The optional-Type overload stays where it was, since the symbol cannot say what a call will pass.
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Includes #213 (parity notes), since it edits the same rows.
Dapper's
Type-argument overloads pick the row type at execution time, which is the one thing compile-time generation cannot follow. Supporting them means a build-time registry of candidate types plus runtime dispatch keyed onType— a lookup on the hot path, an open world for the trimmer, and dispatch ILC cannot resolve unless every announced type is rooted. That is the shape #206 was closed over; rebuilding it for a lower-value feature would be incoherent.It costs no behaviour. These already generated nothing — a five-call probe handled 0 of 5. What changes is what we say: DAP056 now fires at the call-site and names the generic overload, replacing either silence or a confusing DAP009 about an unexpected
typeparameter.Detection is call-site sensitive, deliberately
GetRowParser<T>(concreteType: null)— the default, and the common case — is perfectly supportable; only a call that actually passes aTypedefers the decision. So the check looks at the arguments, not the symbol.GetRowParser<T>()stays supported, and the fixture pins both halves:GetRowParser(concreteType)goes tooIt is the one row where "use the generic form" is not available advice, because the choice is data-dependent — so
docs/rules/DAP056.mdgives the pattern that is actually correct under AOT: aswitchoverGetRowParser<T>()per candidate type. More code, and strictly better, because it roots exactly the types you use where a registry roots everything registered.Reported from the generator, not the analyzer
Most of these overloads carry no
sqlstring, so the analyzer never sees them (the reason 7 of them were in the silent bucket).SkippedSourceStategains a reason enum — plain data, so the cached model stays equatable andModelShapeTestsstays happy — andGenerateemits from it.Knock-on effects
non-goal: Type-basedbucket for overloads whoseTypeparameter is required, so silent drops 27 → 22 and undiagnosed-unsupported 13 → 12; the mute total goes 40 → 34;GetRowParser's existing fixture goes from 1 silent skip to 0;Typeoverload stays in its previous bucket, because a symbol cannot say what a call will pass — the report's stated bound;Suites green on net8.0 (369) and net48 (362); solution builds clean.