fix(PC0021): strip AppSource mandatory affixes before field name comparison

.github/instructions/common-library.instructions.md

@@ -46,7 +46,8 @@ Higher-level utilities that wrap SDK functionality.
 
 | File | Purpose |
 |------|---------|
-| `AppSourceCopConfigurationProvider.cs` | Adapter wrapping `Microsoft.Dynamics.Nav.Analyzers.Common.AppSourceCopConfiguration`. Exposes `MandatoryAffixes`, `MandatorySuffix`, `MandatoryPrefix`. Uses init-only setters on net8.0, regular setters on netstandard2.1. |
+| `AppSourceCopConfigurationProvider.cs` | Adapter wrapping `Microsoft.Dynamics.Nav.Analyzers.Common.AppSourceCopConfiguration`. Exposes `MandatoryAffixes`, `MandatorySuffix`, `MandatoryPrefix` via `GetAppSourceCopConfiguration(Compilation)` (SDK-cached per module spec) and the merged affix list via `GetMandatoryNameAffixes(Compilation)` (delegates to the SDK merge; NOT cached — re-reads AppSourceCop.json every call, so cache per compilation at the call site). Uses init-only setters on net8.0, regular setters on netstandard2.1. |
+| `MandatoryAffixes.cs` | Shared AppSourceCop mandatory-affix logic (loose SDK semantics: every configured value from `mandatoryPrefix`/`mandatorySuffix`/`mandatoryAffixes` is a candidate at either end of a name). `GetAffixes(Compilation)` (delegates to `AppSourceCopConfigurationProvider.GetMandatoryNameAffixes`; cache per compilation at the call site), `GetIndexAfterLeadingAffix(name, affixes)` (nullable index after a leading affix; requires a non-empty remainder), `StripAffixes(name, affixes)` (removes at most one affix per end, trims residual whitespace, never returns empty). Used by LC0054 (InterfaceObjectNameGuide) and PC0021 (TransferFieldsNameMismatch, issue #436). |
 | `ManifestHelper.cs` | `GetManifest(Compilation)` returning `NavAppManifest?`. On net8.0 delegates directly; on netstandard2.1 uses reflection to create a typed delegate, trying two different type paths for AL version compatibility. **Throws `FileNotFoundException` in test contexts** because `Microsoft.Dynamics.Nav.Analyzers.Common` assembly isn't available. Analyzers must catch this and treat as null manifest. |
 | `ODataNameHelper.cs` | `MangleIntoValidXmlIdentifier(string name)` returning `string?`. Accesses `NameTransformations.MangleIntoValidXmlIdentifier` in `Microsoft.Dynamics.Nav.AL.Common` via `Type.GetType()` + `GetMethod()` + `CreateDelegate()`. Returns null if the SDK method is unavailable (older SDK versions). Callers should check `IsAvailable` property to exit early. Used by PC0033 (DuplicateODataEntityName). |
 | `AcronymRegistry.cs` | Case-insensitive registry of canonical acronym casings (`LCY`, `OData`, `UoM`, `VAT`, ...). Exposes `DefaultAcronyms` (curated BC/web/data list as a flat array, excludes 2-letter abbreviations and `ID`), `Default` singleton, `Create(IEnumerable<string>?)` merge factory, `TryGetCanonical(word, out canonical)` (returns the preferred first-added variant), and `TryGetVariants(word, out variants)` (returns all registered variants for the case-insensitive key, ordered; first entry is canonical). Supports **multiple variants per key** — e.g. defaults list both `BoM`/`Bom` and `UoM`/`Uom`. User entries for a key **displace** built-in variants for that key (user list is authoritative per key; multiple user entries under the same key accumulate). Used by LC0098 (EventSubscriberNamingPattern); designed as shared infrastructure for future rules that render identifiers from natural-language input. |

.github/instructions/instruction-maintenance.instructions.md

@@ -94,6 +94,7 @@ Include: project structure, templates, step-by-step guides, API reference, commo
 | `sdk-analyzer-infrastructure` | `'src/ALCops.*/Analyzers/**'` | NAV SDK internals: callback ordering, incremental compilation, GetOperation perf |
 | `analyzer-exception-harness` | `'src/ALCops.Common/Diagnostics/**'` | XX0000 harness: base class + context decorators that convert analyzer exceptions into located diagnostics |
 | `fc0002-casing-mismatch` | rule-scoped | FC0002 rule (both analyzers, XmlPort casing matrix) |
+| `lc0054-interface-object-name-guide` | rule-scoped | LC0054 rule (shared MandatoryAffixes helper) |
 | `fc0004-permission-declaration-order` | rule-scoped | FC0004 rule |
 | `fc0005-use-parenthesis-for-method-assignment` | rule-scoped | FC0005 rule |
 | `fc0006-permission-values-should-be-lowercase` | rule-scoped | FC0006 rule |

.github/instructions/lc0054-interface-object-name-guide.instructions.md

@@ -0,0 +1,51 @@
+---
+applyTo: 'src/ALCops.LinterCop/**/InterfaceObjectNameGuide*'
+---
+
+# LC0054: Interface Object Name Guide
+
+## Purpose
+
+Interface object names should follow the naming guide: start with a capital `I`, no whitespace
+directly after the `I`. When AppSource mandatory affixes are configured, the name may start with
+an affix (e.g. `"ABC ICustomer"`); the `I` rule then applies to the remainder after the affix.
+
+## Diagnostic properties
+
+| Property | Value |
+|---|---|
+| ID | `LC0054` |
+| Category | Design |
+| Severity | Warning |
+| Enabled by default | **No** (tests enable it via a ruleset) |
+| Location | Interface object name |
+
+## Design decisions
+
+| Decision | Rationale |
+|---|---|
+| Affix logic lives in `ALCops.Common.Helpers.MandatoryAffixes` | Shared with PC0021 (issue #436); loose SDK semantics via `AppSourceCopConfigurationProvider.GetMandatoryNameAffixes` |
+| `mandatorySuffix` is a candidate leading affix | Behavior alignment with the SDK's own affix validation (`RuleIdentifiersMustHaveValidAffixes`): every configured value is valid at either end. Previously LC0054 ignored `mandatorySuffix` |
+| Affixes resolved per compilation via `CompilationStartAction` closure + `Lazy<string[]>` | Replaced a static mutable `Affixes` field populated by a compilation-start action (cross-compilation data race). The SDK's `GetMandatoryNameAffixes(Compilation)` re-reads AppSourceCop.json, so the `Lazy` caches it per compilation |
+| Fast path: name starts with `I` and no whitespace at index 1 (or name is exactly `"I"`) | No affix lookup needed for compliant names. Length guard fixes a pre-existing `IndexOutOfRangeException` for a name of exactly `"I"` |
+| Empty-remainder guard after affix strip | `RemoveSpecialCharacters(remainder)` can be empty (e.g. `"ABC -"`); report instead of indexing `[0]` |
+
+## Analyzer flow
+
+1. Skip obsolete symbols; require `IInterfaceTypeSymbol`.
+2. Name starts with `I` and is single-character or `name[1]` is not whitespace → compliant, return.
+3. `MandatoryAffixes.GetIndexAfterLeadingAffix(name, affixes)` → null ⇒ report.
+4. Remainder after the affix has no letters/digits, or its first letter/digit is not `I` ⇒ report.
+5. Whitespace directly after the first `I` in the remainder ⇒ report.
+
+## Test coverage
+
+Located in `src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/`. Because the rule is
+disabled by default, `AnalyzerTestFixtureConfig.RuleSetPath` points to
+`InterfaceObjectNameGuide.ruleset.json` (action `Warning`). Affix cases inject an
+`AppSourceCop.json` (`mandatoryPrefix: "ABC "`, `mandatorySuffix: "XYZ "`,
+`mandatoryAffixes: ["FOO "]`) via `MemoryFileSystem` in dedicated
+`HasDiagnosticWithAffixes`/`NoDiagnosticWithAffixes` methods.
+
+**HasDiagnostic (5 cases):** NoLeadingI, WhitespaceAfterI, AffixWithoutI, AffixThenIWithWhitespace, AffixThenNoLettersOrDigits.
+**NoDiagnostic (5 cases):** LeadingI, SingleCharacterI, PrefixThenI, AffixThenI, SuffixAsLeadingAffixThenI.

.github/instructions/pc0020-pc0021-transferfields-schema-compatibility.instructions.md

@@ -41,6 +41,9 @@ PK fields; a constant-`true` third argument (`SkipFieldsNotMatchingType`) suppre
 | Use `IsRemoved()` (Removed/Moved), NOT `IsObsolete()` | `ObsoleteState = Pending` tables/fields still participate at runtime and must keep firing |
 | Field-level `#pragma warning disable` honored on either side | Checked via `IsEitherFieldSuppressed` against field syntax directives |
 | Enum→Integer, Code→Text, Integer→BigInteger/Decimal treated as compatible | Safe implicit conversions performed by the platform |
+| Mandatory affixes stripped before name comparison (PC0021 only) | Issue #436: AppSource `mandatoryPrefix`/`mandatorySuffix`/`mandatoryAffixes` force extension field names to differ from the paired field. `AreFieldNamesEquivalent` compares raw names first, then affix-stripped effective names via `MandatoryAffixes.StripAffixes` (loose SDK semantics: any affix, either end; whitespace trimmed after strip) |
+| Affix stripping only for TableExtension fields declared in the current module | Fields on own (non-extension) tables carry the affix on the table object, not the fields; dependency extensions have their own unknown affixes. Checked via `field.ContainingSymbol is ITableExtensionTypeSymbol` + `field.Location` in the compilation's syntax-tree paths |
+| Affix list cached per `Compilation` via `ConditionalWeakTable` (`AffixesCache`) | The SDK's `GetMandatoryNameAffixes(Compilation)` re-reads AppSourceCop.json on every call (it bypasses the SDK's module-spec config cache) |
 
 ## SDK behavior notes
 
@@ -58,8 +61,14 @@ Rules folders: `Rules/TransferFieldsTypeMismatch/` and `Rules/TransferFieldsName
 
 **TransferFieldsTypeMismatch HasDiagnostic (17 cases):** InvocationRecWithCodeunit, InvocationRecWithPage, InvocationRecWithTable, InvocationRecWithTablexRec, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsTrue, InvocationWithReturnValue, InvocationWithVarGlobals, InvocationWithVarLocalAndGlobal, InvocationWithVarLocals, InvocationWithVarParam, InvocationWithTableExtension, Invocation_SourceTableObsoleteStatePending, TableExt_Multiple_SameBase, TableExtension, TableExtensionTypeWithType, TableExtensionTypeWithTypeLength.
 **TransferFieldsTypeMismatch NoDiagnostic (18 cases):** BuiltInInvocation, Invocation_ObsoleteStateRemoved, Invocation_Pragma, Invocation_SourceTableObsoleteStateRemoved, Invocation_TargetTableObsoleteStateRemoved, InvocationCodeToText, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsFalse, InvocationWithTableExtension, InvocationWithType, InvocationWithTypeLength, TableExt_BothObsoleteStateRemoved, TableExt_ObsoleteStateRemoved, TableExt_Paired_Extension_Pragma, TableExt_Paired_SingleTableExt, TableExt_SourceBaseTableObsoleteStateRemoved, TableExt_TargetBaseTableObsoleteStateRemoved, TableExt_Unpaired.
-**TransferFieldsNameMismatch HasDiagnostic (16 cases):** InvocationRecWithCodeunit, InvocationRecWithPage, InvocationRecWithTable, InvocationRecWithTablexRec, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsTrue, InvocationWithReturnValue, InvocationWithVarGlobals, InvocationWithVarLocalAndGlobal, InvocationWithVarLocals, InvocationWithVarParam, InvocationWithTableExtension, Invocation_SourceTableObsoleteStatePending, TableExt_Multiple_SameBase, TableExtension, TableExt_NamespaceCasingMismatch.
-**TransferFieldsNameMismatch NoDiagnostic (14 cases):** BuiltInInvocation, Invocation_ObsoleteStateRemoved, Invocation_Pragma, Invocation_SourceTableObsoleteStateRemoved, Invocation_TargetTableObsoleteStateRemoved, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsFalse, InvocationWithTableExtension, TableExt_ObsoleteStateRemoved, TableExt_Paired_Extension_Pragma, TableExt_Paired_SingleTableExt, TableExt_SourceBaseTableObsoleteStateRemoved, TableExt_TargetBaseTableObsoleteStateRemoved, TableExt_Unpaired.
+**TransferFieldsNameMismatch HasDiagnostic (18 cases):** InvocationRecWithCodeunit, InvocationRecWithPage, InvocationRecWithTable, InvocationRecWithTablexRec, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsTrue, InvocationWithReturnValue, InvocationWithVarGlobals, InvocationWithVarLocalAndGlobal, InvocationWithVarLocals, InvocationWithVarParam, InvocationWithTableExtension, Invocation_SourceTableObsoleteStatePending, TableExt_Multiple_SameBase, TableExtension, TableExt_NamespaceCasingMismatch, Affix_Invocation_CoreNameDiffers, Affix_Invocation_OwnTableFieldsNotStripped.
+**TransferFieldsNameMismatch NoDiagnostic (18 cases):** BuiltInInvocation, Invocation_ObsoleteStateRemoved, Invocation_Pragma, Invocation_SourceTableObsoleteStateRemoved, Invocation_TargetTableObsoleteStateRemoved, InvocationSkipFieldsNotMatchingType, InvocationWithInitPrimaryKeyFieldsIsFalse, InvocationWithTableExtension, TableExt_ObsoleteStateRemoved, TableExt_Paired_Extension_Pragma, TableExt_Paired_SingleTableExt, TableExt_SourceBaseTableObsoleteStateRemoved, TableExt_TargetBaseTableObsoleteStateRemoved, TableExt_Unpaired, Affix_Invocation_PrefixStripped, Affix_Invocation_SuffixStripped, Affix_Invocation_AffixTrimmed, Affix_TableExt_BothSidesStripped.
+
+The `Affix_*` cases run in dedicated `HasDiagnosticWithAffixes`/`NoDiagnosticWithAffixes` methods that
+inject an `AppSourceCop.json` (`mandatoryPrefix: "ABC "`, `mandatorySuffix: " XYZ"`,
+`mandatoryAffixes: ["FOO"]`) via `MemoryFileSystem`. This requires
+`Microsoft.Dynamics.Nav.Analyzers.Common.dll` as a `Private=True` reference in the test csproj
+(ALCops.Common references it with `Private=False`).
 
 ## Known issues
 

src/ALCops.Common/Helpers/AppSourceCopConfigurationProvider.cs

@@ -15,6 +15,18 @@ public static class AppSourceCopConfigurationProvider
 
         return AppSourceCopConfiguration.From(appSourceCopConf);
     }
+
+    /// <summary>
+    /// Returns the merged, distinct, non-empty list of mandatory affixes (mandatoryPrefix,
+    /// mandatorySuffix and mandatoryAffixes) for the compilation's AppSourceCop.json, or an
+    /// empty array when none is present. Delegates to the SDK so the merge semantics stay
+    /// identical to AppSourceCop's own affix validation. Note: unlike
+    /// <see cref="GetAppSourceCopConfiguration"/>, the underlying SDK overload re-reads the
+    /// configuration on every call; cache the result per compilation at the call site.
+    /// </summary>
+    public static string[] GetMandatoryNameAffixes(Compilation compilation)
+        => Microsoft.Dynamics.Nav.Analyzers.Common.AppSourceCopConfiguration.AppSourceCopConfigurationProvider
+            .GetMandatoryNameAffixes(compilation);
 }
 
 public sealed class AppSourceCopConfiguration

src/ALCops.Common/Helpers/MandatoryAffixes.cs

@@ -0,0 +1,76 @@
+using ALCops.Common.Extensions;
+using Microsoft.Dynamics.Nav.CodeAnalysis;
+
+namespace ALCops.Common.Helpers;
+
+/// <summary>
+/// Shared logic for AppSourceCop mandatory affixes (mandatoryPrefix, mandatorySuffix and
+/// mandatoryAffixes). Mirrors the SDK's loose semantics where every configured value is a
+/// candidate at either end of a name (see AppSourceCop's RuleIdentifiersMustHaveValidAffixes
+/// and AppSourceCopConfigurationProvider.GetMandatoryNameAffixes).
+/// </summary>
+public static class MandatoryAffixes
+{
+    /// <summary>
+    /// Returns the merged, distinct, non-empty list of mandatory affixes for the compilation.
+    /// Returns an empty array when no AppSourceCop.json is present or no affixes are configured.
+    /// Delegates to the SDK's own merge (AppSourceCopConfigurationProvider.GetMandatoryNameAffixes),
+    /// which re-reads the configuration on every call; cache the result per compilation at the
+    /// call site (e.g. a CompilationStartAction closure or a ConditionalWeakTable).
+    /// </summary>
+    public static string[] GetAffixes(Compilation compilation)
+        => AppSourceCopConfigurationProvider.GetMandatoryNameAffixes(compilation);
+
+    /// <summary>
+    /// Returns the index of the first character after a leading affix, or <c>null</c> when the
+    /// name does not start with any affix or no character follows the affix.
+    /// </summary>
+    public static int? GetIndexAfterLeadingAffix(string name, string[] affixes)
+    {
+        foreach (string affix in affixes)
+        {
+            if (name.Length > affix.Length && name.StartsWith(affix, SemanticFacts.NameEqualityComparison))
+                return affix.Length;
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Removes at most one affix from the start and at most one affix from the end of the name,
+    /// trimming residual whitespace after each removal. Never returns an empty string: a removal
+    /// that would consume the entire name is skipped.
+    /// </summary>
+    public static string StripAffixes(string name, string[] affixes)
+        => StripTrailingAffix(StripLeadingAffix(name, affixes), affixes);
+
+    private static string StripLeadingAffix(string name, string[] affixes)
+    {
+        foreach (string affix in affixes)
+        {
+            if (name.Length <= affix.Length || !name.StartsWith(affix, SemanticFacts.NameEqualityComparison))
+                continue;
+
+            string stripped = name.Substring(affix.Length).TrimStart();
+            if (stripped.Length > 0)
+                return stripped;
+        }
+
+        return name;
+    }
+
+    private static string StripTrailingAffix(string name, string[] affixes)
+    {
+        foreach (string affix in affixes)
+        {
+            if (name.Length <= affix.Length || !name.EndsWith(affix, SemanticFacts.NameEqualityComparison))
+                continue;
+
+            string stripped = name.Substring(0, name.Length - affix.Length).TrimEnd();
+            if (stripped.Length > 0)
+                return stripped;
+        }
+
+        return name;
+    }
+}

src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/HasDiagnostic/AffixThenIWithWhitespace.al

@@ -0,0 +1,5 @@
+interface [|"ABC I Customer"|]
+{
+    // After stripping the mandatory prefix "ABC ", a whitespace follows the 'I'
+    procedure DoSomething();
+}

src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/HasDiagnostic/AffixThenNoLettersOrDigits.al

@@ -0,0 +1,5 @@
+interface [|"ABC -"|]
+{
+    // After stripping the mandatory prefix "ABC ", no letters or digits remain
+    procedure DoSomething();
+}

src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/HasDiagnostic/AffixWithoutI.al

@@ -0,0 +1,5 @@
+interface [|"ABC Customer"|]
+{
+    // Mandatory prefix "ABC " is stripped, but the remainder does not start with 'I'
+    procedure DoSomething();
+}

src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/HasDiagnostic/NoLeadingI.al

@@ -0,0 +1,4 @@
+interface [|Customer|]
+{
+    procedure DoSomething();
+}

src/ALCops.LinterCop.Test/Rules/InterfaceObjectNameGuide/HasDiagnostic/WhitespaceAfterI.al

@@ -0,0 +1,4 @@
+interface [|"I Customer"|]
+{
+    procedure DoSomething();
+}