implements PR015

docs/pbs/pull-requests/PR-013-pbs-import-unresolved-diagnostics.md

@@ -1,44 +0,0 @@
-# PR-013 - PBS Unresolved Import Diagnostics
-
-## Briefing
-
-Import resolution currently ignores missing target modules in frontend linking validation. This PR enforces deterministic diagnostics for unresolved module imports and unresolved imported symbols.
-
-## Motivation
-
-Silent import misses break the diagnostics contract and defer user-actionable errors.
-
-## Target
-
-- Module import validation in `PbsModuleVisibilityValidator`.
-- Linking diagnostic coverage for import failures.
-
-## Scope
-
-- Emit errors for missing target module references.
-- Keep existing public-symbol checks.
-- Preserve deterministic, source-first attribution.
-
-## Method
-
-- Extend import validation to detect absent target modules.
-- Report diagnostics on the importing site.
-- Keep related-span behavior where applicable.
-
-## Acceptance Criteria
-
-- Importing a non-existent module always emits deterministic linking/import diagnostic.
-- Importing a non-public symbol still emits existing diagnostic.
-- Diagnostic attribution points to import site.
-- No silent pass for unresolved imports remains.
-
-## Tests
-
-- Add tests for missing module import.
-- Add tests for missing symbol import in existing module.
-- Verify phase and diagnostic code stability.
-
-## Non-Goals
-
-- Full manifest/dependency resolver redesign.
-- Loader/runtime capability checks.

docs/pbs/pull-requests/PR-014-pbs-switch-wildcard-rules.md

@@ -1,42 +0,0 @@
-# PR-014 - PBS Switch Wildcard Rule Enforcement
-
-## Briefing
-
-Switch semantics do not currently enforce all wildcard constraints. This PR enforces: at most one wildcard arm, and rejection of mixed `default` and `_` in the same switch.
-
-## Motivation
-
-Wildcard ambiguity weakens deterministic static semantics and conformance.
-
-## Target
-
-- Switch expression semantic validation in flow analyzer.
-- Required static diagnostics for wildcard rule violations.
-
-## Scope
-
-- Enforce wildcard-count and wildcard-mixing rules.
-- Preserve existing selector/type compatibility checks.
-
-## Method
-
-- Track wildcard token form used per switch arm.
-- Emit diagnostics for duplicate wildcard and mixed wildcard spellings.
-- Keep existing exhaustiveness behavior.
-
-## Acceptance Criteria
-
-- Two wildcard arms are rejected deterministically.
-- `default` + `_` in one switch is rejected deterministically.
-- Existing duplicate-pattern logic for non-wildcards remains unchanged.
-
-## Tests
-
-- Add tests for duplicate wildcard arms.
-- Add tests for mixed `default`/`_` arms.
-- Run semantic control-flow suite.
-
-## Non-Goals
-
-- New switch syntax.
-- Runtime switch lowering changes.

docs/pbs/pull-requests/PR-015-pbs-this-self-context-validation.md

@@ -1,43 +0,0 @@
-# PR-015 - PBS this/Self Context Validation
-
-## Briefing
-
-The frontend accepts `this` and `Self` outside allowed contexts without required diagnostics. This PR adds explicit static checks for invalid usage.
-
-## Motivation
-
-Context-free acceptance of `this`/`Self` is non-conformant and creates type ambiguity.
-
-## Target
-
-- `this` expression analysis.
-- `Self` type-surface analysis in declarations.
-- Error catalog and deterministic diagnostics.
-
-## Scope
-
-- Reject `this` outside struct method, service method, and ctor bodies.
-- Reject `Self` outside struct/service method declarations and ctors.
-
-## Method
-
-- Add callable-context metadata into flow/type validation.
-- Emit dedicated diagnostics for invalid `this` and invalid `Self` usage.
-- Keep valid owner contexts unchanged.
-
-## Acceptance Criteria
-
-- Invalid `this` usage emits deterministic static diagnostic.
-- Invalid `Self` usage emits deterministic static diagnostic.
-- Valid struct/service/ctor contexts remain accepted.
-
-## Tests
-
-- Add positive tests for valid `this`/`Self` contexts.
-- Add negative tests for top-level functions and unrelated declarations.
-- Run declaration + flow semantic suites.
-
-## Non-Goals
-
-- Introducing new receiver features.
-- Altering `Self` syntax.

prometeu-compiler/frontends/prometeu-frontend-pbs/src/main/java/p/studio/compiler/pbs/semantics/PbsDeclarationRuleValidator.java

@@ -29,12 +29,20 @@ final class PbsDeclarationRuleValidator {
             final PbsAst.ReturnKind returnKind,
             final PbsAst.TypeRef returnType,
             final PbsAst.TypeRef resultErrorType,
-            final Span span) {
+            final Span span,
+            final boolean allowSelf) {
         validateParameters(parameters, "callable '%s'".formatted(callableName));
-        validateReturnSurface(returnKind, returnType, resultErrorType, "callable '%s'".formatted(callableName), span);
+        validateReturnSurface(
+                returnKind,
+                returnType,
+                resultErrorType,
+                "callable '%s'".formatted(callableName),
+                span,
+                allowSelf);
         PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(
                 parameters.stream().map(PbsAst.Parameter::typeRef).toList(),
                 "callable '%s'".formatted(callableName),
+                allowSelf,
                 diagnostics);
     }
 
@@ -58,8 +66,9 @@ final class PbsDeclarationRuleValidator {
 
     void validateTypeSurfaces(
             final List<PbsAst.TypeRef> typeRoots,
-            final String ownerDescription) {
+            final String ownerDescription,
-        PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(typeRoots, ownerDescription, diagnostics);
+            final boolean allowSelf) {
+        PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(typeRoots, ownerDescription, allowSelf, diagnostics);
     }
 
     void validateErrorDeclaration(final PbsAst.ErrorDecl errorDecl) {
@@ -114,10 +123,12 @@ final class PbsDeclarationRuleValidator {
                 callbackDecl.returnType(),
                 callbackDecl.resultErrorType(),
                 "callback '%s'".formatted(callbackDecl.name()),
-                callbackDecl.span());
+                callbackDecl.span(),
+                false);
         PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(
                 callbackDecl.parameters().stream().map(PbsAst.Parameter::typeRef).toList(),
                 "callback '%s'".formatted(callbackDecl.name()),
+                false,
                 diagnostics);
     }
 
@@ -131,6 +142,7 @@ final class PbsDeclarationRuleValidator {
             PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(
                     List.of(constDecl.explicitType()),
                     "const '%s'".formatted(constDecl.name()),
+                    false,
                     diagnostics);
         }
 
@@ -147,7 +159,8 @@ final class PbsDeclarationRuleValidator {
             final PbsAst.TypeRef returnType,
             final PbsAst.TypeRef resultErrorType,
             final String ownerDescription,
-            final Span span) {
+            final Span span,
+            final boolean allowSelf) {
         if (returnKind == PbsAst.ReturnKind.RESULT && PbsTypeSurfaceSemanticsValidator.isOptionalType(returnType)) {
             p.studio.compiler.source.diagnostics.Diagnostics.error(diagnostics, 
                     PbsSemanticsErrors.E_SEM_INVALID_MIXED_OPTIONAL_RESULT_RETURN.name(),
@@ -160,10 +173,10 @@ final class PbsDeclarationRuleValidator {
         }
 
         if (returnType != null) {
-            PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(List.of(returnType), ownerDescription, diagnostics);
+            PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(List.of(returnType), ownerDescription, allowSelf, diagnostics);
         }
         if (resultErrorType != null) {
-            PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(List.of(resultErrorType), ownerDescription, diagnostics);
+            PbsTypeSurfaceSemanticsValidator.validateTypeSurfaceRecursive(List.of(resultErrorType), ownerDescription, allowSelf, diagnostics);
         }
     }
 

prometeu-compiler/frontends/prometeu-frontend-pbs/src/main/java/p/studio/compiler/pbs/semantics/PbsDeclarationSemanticsValidator.java

@@ -23,6 +23,7 @@ public final class PbsDeclarationSemanticsValidator {
                         functionDecl.returnType(),
                         functionDecl.resultErrorType(),
                         functionDecl.span(),
+                        false,
                         binder,
                         rules);
                 continue;
@@ -83,6 +84,10 @@ public final class PbsDeclarationSemanticsValidator {
             final PbsDeclarationRuleValidator rules,
             final DiagnosticSink diagnostics) {
         final var ownerNameId = nameTable.register(structDecl.name());
+        rules.validateTypeSurfaces(
+                structDecl.fields().stream().map(PbsAst.StructField::typeRef).toList(),
+                "struct '%s'".formatted(structDecl.name()),
+                false);
         final var methodScope = PbsCallableScope.structMethods(ownerNameId);
         for (final var method : structDecl.methods()) {
             validateCallable(
@@ -93,6 +98,7 @@ public final class PbsDeclarationSemanticsValidator {
                     method.returnType(),
                     method.resultErrorType(),
                     method.span(),
+                    true,
                     binder,
                     rules);
         }
@@ -102,7 +108,8 @@ public final class PbsDeclarationSemanticsValidator {
             rules.validateParameters(ctor.parameters(), "ctor '%s'".formatted(ctor.name()));
             rules.validateTypeSurfaces(
                     ctor.parameters().stream().map(PbsAst.Parameter::typeRef).toList(),
-                    "ctor '%s'".formatted(ctor.name()));
+                    "ctor '%s'".formatted(ctor.name()),
+                    true);
 
             binder.registerCtor(ctorScope, ctor.name(), PbsCallableShape.ctorShapeKey(ctor.parameters()), ctor.span());
             if (PbsCtorReturnScanner.containsReturnStatement(ctor.body())) {
@@ -128,6 +135,7 @@ public final class PbsDeclarationSemanticsValidator {
                     method.returnType(),
                     method.resultErrorType(),
                     method.span(),
+                    true,
                     binder,
                     rules);
         }
@@ -147,6 +155,7 @@ public final class PbsDeclarationSemanticsValidator {
                     signature.returnType(),
                     signature.resultErrorType(),
                     signature.span(),
+                    false,
                     binder,
                     rules);
         }
@@ -167,6 +176,7 @@ public final class PbsDeclarationSemanticsValidator {
                     method.returnType(),
                     method.resultErrorType(),
                     method.span(),
+                    false,
                     binder,
                     rules);
         }
@@ -180,9 +190,10 @@ public final class PbsDeclarationSemanticsValidator {
             final PbsAst.TypeRef returnType,
             final PbsAst.TypeRef resultErrorType,
             final Span span,
+            final boolean allowSelf,
             final PbsNamespaceBinder binder,
             final PbsDeclarationRuleValidator rules) {
-        rules.validateCallableHeader(callableName, parameters, returnKind, returnType, resultErrorType, span);
+        rules.validateCallableHeader(callableName, parameters, returnKind, returnType, resultErrorType, span, allowSelf);
         binder.registerCallable(
                 scope,
                 callableName,

prometeu-compiler/frontends/prometeu-frontend-pbs/src/main/java/p/studio/compiler/pbs/semantics/PbsFlowExpressionAnalyzer.java

@@ -97,8 +97,15 @@ final class PbsFlowExpressionAnalyzer {
         if (expression instanceof PbsAst.UnitExpr) {
             return ExprResult.type(TypeView.unit());
         }
-        if (expression instanceof PbsAst.ThisExpr) {
+        if (expression instanceof PbsAst.ThisExpr thisExpr) {
-            return ExprResult.type(receiverType == null ? TypeView.unknown() : receiverType);
+            if (receiverType == null) {
+                p.studio.compiler.source.diagnostics.Diagnostics.error(diagnostics,
+                        PbsSemanticsErrors.E_SEM_INVALID_THIS_CONTEXT.name(),
+                        "Invalid 'this' usage outside struct/service methods and constructors",
+                        thisExpr.span());
+                return ExprResult.type(TypeView.unknown());
+            }
+            return ExprResult.type(receiverType);
         }
         if (expression instanceof PbsAst.IdentifierExpr identifierExpr) {
             final var localType = scope.resolve(identifierExpr.name());

prometeu-compiler/frontends/prometeu-frontend-pbs/src/main/java/p/studio/compiler/pbs/semantics/PbsSemanticsErrors.java

@@ -18,6 +18,8 @@ public enum PbsSemanticsErrors {
     E_SEM_APPLY_AMBIGUOUS_OVERLOAD,
     E_SEM_BARE_METHOD_EXTRACTION,
     E_SEM_INVALID_MEMBER_ACCESS,
+    E_SEM_INVALID_THIS_CONTEXT,
+    E_SEM_INVALID_SELF_CONTEXT,
     E_SEM_IF_NON_BOOL_CONDITION,
     E_SEM_IF_BRANCH_TYPE_MISMATCH,
     E_SEM_SWITCH_SELECTOR_INVALID,

prometeu-compiler/frontends/prometeu-frontend-pbs/src/main/java/p/studio/compiler/pbs/semantics/PbsTypeSurfaceSemanticsValidator.java

@@ -13,6 +13,7 @@ final class PbsTypeSurfaceSemanticsValidator {
     static void validateTypeSurfaceRecursive(
             final List<PbsAst.TypeRef> roots,
             final String ownerDescription,
+            final boolean allowSelf,
             final DiagnosticSink diagnostics) {
         final var pending = new ArrayList<>(roots);
         while (!pending.isEmpty()) {
@@ -37,6 +38,14 @@ final class PbsTypeSurfaceSemanticsValidator {
                         pending.add(field.typeRef());
                     }
                 }
+                case SELF -> {
+                    if (!allowSelf) {
+                        p.studio.compiler.source.diagnostics.Diagnostics.error(diagnostics,
+                                PbsSemanticsErrors.E_SEM_INVALID_SELF_CONTEXT.name(),
+                                "Invalid 'Self' type usage in %s".formatted(ownerDescription),
+                                typeRef.span());
+                    }
+                }
                 default -> {
                     // No recursive children.
                 }

prometeu-compiler/frontends/prometeu-frontend-pbs/src/test/java/p/studio/compiler/pbs/semantics/PbsSemanticsControlFlowTest.java

@@ -6,6 +6,7 @@ import p.studio.compiler.source.diagnostics.DiagnosticSink;
 import p.studio.compiler.source.identifiers.FileId;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class PbsSemanticsControlFlowTest {
@@ -82,4 +83,44 @@ class PbsSemanticsControlFlowTest {
                 .count();
         assertEquals(1, duplicateWildcardCount);
     }
+
+    @Test
+    void shouldAllowThisInsideStructServiceAndCtorBodies() {
+        final var source = """
+                declare struct Box(v: int) {
+                  fn read() -> int { return this.v; }
+                  ctor make(seed: int) { this.v = seed; }
+                }
+
+                declare service Game {
+                  fn ping() -> int { this; return 0; }
+                }
+
+                fn ok() -> int { return 0; }
+                """;
+        final var diagnostics = DiagnosticSink.empty();
+
+        new PbsFrontendCompiler().compileFile(new FileId(0), source, diagnostics);
+
+        assertFalse(diagnostics.stream().anyMatch(d ->
+                d.getCode().equals(PbsSemanticsErrors.E_SEM_INVALID_THIS_CONTEXT.name())));
+    }
+
+    @Test
+    void shouldRejectThisOutsideReceiverContexts() {
+        final var source = """
+                fn bad() -> int {
+                  this;
+                  return 0;
+                }
+                """;
+        final var diagnostics = DiagnosticSink.empty();
+
+        new PbsFrontendCompiler().compileFile(new FileId(0), source, diagnostics);
+
+        final var invalidThisCount = diagnostics.stream()
+                .filter(d -> d.getCode().equals(PbsSemanticsErrors.E_SEM_INVALID_THIS_CONTEXT.name()))
+                .count();
+        assertEquals(1, invalidThisCount);
+    }
 }

prometeu-compiler/frontends/prometeu-frontend-pbs/src/test/java/p/studio/compiler/pbs/semantics/PbsSemanticsDeclarationsTest.java

@@ -5,6 +5,7 @@ import p.studio.compiler.pbs.PbsFrontendCompiler;
 import p.studio.compiler.source.diagnostics.DiagnosticSink;
 import p.studio.compiler.source.identifiers.FileId;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -144,4 +145,40 @@ class PbsSemanticsDeclarationsTest {
         assertTrue(diagnostics.stream().anyMatch(d ->
                 d.getCode().equals(PbsSemanticsErrors.E_SEM_DUPLICATE_DECLARATION.name())));
     }
+
+    @Test
+    void shouldAllowSelfInStructServiceMethodsAndCtors() {
+        final var source = """
+                declare struct Box(v: int) {
+                  fn merge(other: Self) -> Self { return this; }
+                  ctor make(copy: Self) { this.v = copy.v; }
+                }
+
+                declare service Game {
+                  fn mirror(current: Self) -> int { return 0; }
+                }
+                """;
+        final var diagnostics = DiagnosticSink.empty();
+
+        new PbsFrontendCompiler().compileFile(new FileId(0), source, diagnostics);
+
+        assertFalse(diagnostics.stream().anyMatch(d ->
+                d.getCode().equals(PbsSemanticsErrors.E_SEM_INVALID_SELF_CONTEXT.name())));
+    }
+
+    @Test
+    void shouldRejectSelfOutsideAllowedDeclarationContexts() {
+        final var source = """
+                fn bad(v: Self) -> int { return 0; }
+                declare const GLOBAL: Self = 1;
+                """;
+        final var diagnostics = DiagnosticSink.empty();
+
+        new PbsFrontendCompiler().compileFile(new FileId(0), source, diagnostics);
+
+        final var invalidSelfCount = diagnostics.stream()
+                .filter(d -> d.getCode().equals(PbsSemanticsErrors.E_SEM_INVALID_SELF_CONTEXT.name()))
+                .count();
+        assertEquals(2, invalidSelfCount);
+    }
 }