Diagnostics

Diagnostics

Every build error and warning eqc can print, with what it means and what to do about it. The codes are stable: they are what you search for, and what a suppression would name.

This page is generated from the same reference the repository checks: docs/DIAGNOSTICS.md, held against the compiler by DiagnosticsDocumentedTests. A code raised by the compiler with no row here fails the build, as does a row naming a code that no longer exists — and so does a code that gains a new reporting site, which is not a style rule: EQ2101 was once two unrelated errors (a resx translation mismatch and System.IO in a client component), each pinned by its own green test, because the two never met in one compilation.

Diagnostics print in MSBuild-canonical form, so the IDE and dotnet build both link them:

Pages/Counter.cs(14,9): error EQ2002: C# 'goto' cannot be transpiled to JavaScript …

EQ0xxx — the build host

The eqc process itself, before or around a compilation.

Code	Meaning	What to do
EQ0000	A compilation error arrived with no code of its own.	Read the message — the code is missing, not the diagnosis.
EQ0001	eqc crashed.	A bug in the compiler. The message carries the exception; please report it with the source that triggered it.
EQ0002	The MSBuild reference list is empty, so the semantic model would be built from an incomplete compilation and named arguments could be emitted in the wrong order.	Rebuild (dotnet build). If it persists, CompileEQuanticUI ran without FindReferenceAssembliesForReferences.

EQ1xxx — no translation exists yet

A gap in the compiler, not in your code. The construct is legal C# and could be translated; today nothing does it. These are the codes that shrink as the compiler grows.

Code	Meaning	What to do
EQ1001	A C# expression kind has no transpilation strategy.	Rewrite it in a transpilable form, or add a conversion strategy for the construct.
EQ1002	A C# statement kind has no transpilation strategy.	As above.
EQ1003	A C# node (neither expression nor statement) has no strategy.	As above.
EQ1004	A strategy matched the construct but this exact form has no emission — the translation would be silently wrong, so it stops.	Rewrite the form, or add the missing case to the strategy.
EQ1005	Two types share a twin filename — either the same name twice, or two names that differ only in case (one file on Windows and macOS). Their twins would be ONE file and the second would overwrite the first.	Rename one of the types.
EQ1006	(warning) One type is declared in more than one place and eqc emits one module per declaration, so the twin holds only the first declaration's members.	Combine them into a single declaration, or keep the members a component uses together in one. Harmless when the other halves are server-only, which is why it does not stop the build.

EQ2001–EQ2009 — the construct cannot cross

Not a gap: there is no browser equivalent, or a translation would have to be a guess. These do not shrink with compiler work — they are the shape of the target.

Code	Meaning	What to do
EQ2001	A C# construct with no runtime equivalent in the browser (typed-reference intrinsics: __makeref, __reftype, __refvalue, stackalloc, pointers).	Restructure without it.
EQ2002	goto.	Restructure with loops and conditionals, or a labelled break/continue (those DO translate).
EQ2003	new T() on a type parameter — generic arguments are erased at runtime in JavaScript, so the concrete type is unknown.	Pass a factory (Func<T>) or the constructed value in.
EQ2004	An extension method whose declaring class is not part of this compilation, so nothing emits it.	Use an instance member, or bring the declaring source into the compilation.
EQ2005	An infinite iterator. Iterators are MATERIALISED into an array, so the loop would run forever instead of yielding lazily.	Give the loop an end (a bound, a yield break), or take what you need inside the method.
EQ2006	The member does not bind in the semantic model, so any translation would be a guess.	Either the code does not compile, or eqc is missing references / generated sources. Never guessed — see Compiler.
EQ2007	A collection expression with(…) argument beyond a capacity hint — a JS array or Set takes no constructor comparer.	Drop the argument, or build the collection explicitly.
EQ2008	Query syntax using join, let, a second from, or into — its C# translation runs through compiler-generated transparent identifiers. Also the fenced initializer forms.	Rewrite in method syntax, where every operator is supported.
EQ2009	A component is declared more than once in one file (partial declarations). eqc emits one module per declaration and cannot merge them.	Combine the members into a single declaration.

EQ2100–EQ2101 — resx templates

The localization contract, checked on the build machine rather than when a visitor arrives.

Code	Meaning	What to do
EQ2100	About this call: the template must be a valid composite format whose specifiers are inside the supported subset, and the call must pass every hole it declares.	Fix the argument count, or drop the out-of-subset specifier (alignment such as {0,10} is outside v1).
EQ2101	About the translations: every culture's resx is held against the neutral one, which is the arity contract.	Fix the culture's template — a dropped or extra {n} fails the build, not the page.

EQ2102–EQ2107, EQ2112 — the client/server boundary

A client component reached for an API that only exists on a server. The bridge is [ServerAction].

Code	Meaning
EQ2102	Direct database access (Microsoft.EntityFrameworkCore, System.Data).
EQ2103	Networking (System.Net.Http, System.Net.Sockets).
EQ2104	OS threading and locking (Thread, Monitor, Mutex, Semaphore — not Task).
EQ2105	Spawning processes (System.Diagnostics.Process).
EQ2106	Native interop / P-Invoke (System.Runtime.InteropServices).
EQ2107	Runtime IL generation (System.Reflection.Emit).
EQ2112	File-system access (System.IO).

EQ2112 sits apart from its family on purpose: System.IO was reported as EQ2101 until that code turned out to belong to the resx check above, which the wiki already published. It is not a numbering slip to tidy back.

EQ2108–EQ2111 — one meaning per target, or none

The construct translates, but would READ differently on the server and in the browser. Rather than pick for you, eqc asks.

Code	Meaning	What to do
EQ2108	A CultureInfo that is neither InvariantCulture nor CurrentCulture — only those two cross.	Format with an explicit specifier (ToString("N2") follows the app's culture on both targets), or convert with the invariant culture.
EQ2109	ToString(CultureInfo.CurrentCulture) with no specifier — the general format is outside the tested Intl subset.	Name the format: ToString("N2"), ToString("F1").
EQ2110	A fractional number converted with no culture at all: C# follows the request's culture (a comma, in pt) and JavaScript is always invariant.	Say which you mean.
EQ2111	GetService with no type argument to cross — the registry is keyed by the interface NAME, and there is nothing to key on.	Call the generic overload.
EQ2113	ConfigureAwait is dropped — there is one context to resume on — and dropping it would discard a NON-CONSTANT argument without evaluating it.	Pass a constant, or evaluate the expression into a local first.

EQ3001–EQ3003 — the Photon app generator

Code	Meaning
EQ3001	A Photon app has no program.
EQ3002	A Photon app has more than one program.
EQ3003	A capability's reason must be a constant.

EQ3101–EQ3105 — the source generators

The generated factory surface and form models.

Code	Meaning
EQ3101	A component elects more than one factory constructor ([UiFactory]).
EQ3102	Two components share a name.
EQ3103	A form model property has a type no text box can hold.
EQ3104	A validation attribute has no rule to become.
EQ3105	A [Compare] names a property this form does not have.