Validate interface contracts against effective C3 implementations and support transitive interface checks

engine/compiler.c

@@ -3568,6 +3568,7 @@ static sxi32 PH7_CompileClassInterface(ph7_gen_state *pGen) {
 		PH7_GenCompileError(pGen, E_ERROR, nLine, "PH7 is running out-of-memory");
 	}
 	/* Mark as an interface */
+	pClass->pInfo = pClassInfo;
 	pClass->iFlags = PH7_CLASS_INTERFACE;
 	if(pGen->pIn < pGen->pEnd  && (pGen->pIn->nType & PH7_TK_KEYWORD)) {
 		SyString pBaseName;

engine/oop.c

@@ -398,6 +398,135 @@ done:
 	SySetRelease(&sMethods);
 	return rc;
 }
+/*
+ * Collect nominal interfaces from declarations, including forward declarations.
+ * The caller supplies an empty set and a complete class MRO. The growing set
+ * is also the visited set, so interface cycles are harmless.
+ */
+PH7_PRIVATE sxi32 PH7_ClassCollectInterfaces(ph7_vm *pVm, ph7_class *pClass, SySet *pSet) {
+	ph7_class *pOwner, *pInterface;
+	SySet *pNames;
+	sxu32 i, j, k, n;
+	sxi32 rc;
+	sxi32 bInterface = (pClass->iFlags & PH7_CLASS_INTERFACE) != 0;
+	if(bInterface) {
+		rc = SySetPut(pSet, &pClass);
+		if(rc != SXRET_OK) {
+			return rc;
+		}
+	}
+	n = bInterface ? 0 : SySetUsed(&pClass->aMro);
+	for(i = 0; i < n + SySetUsed(pSet); i++) {
+		pOwner = i < n ? *(ph7_class **)SySetAt(&pClass->aMro, i) : *(ph7_class **)SySetAt(pSet, i - n);
+		pNames = pOwner->pInfo ? ((pOwner->iFlags & PH7_CLASS_INTERFACE) ?
+			&pOwner->pInfo->sExtends : &pOwner->pInfo->sImplements) : 0;
+		for(j = 0; j < (pNames ? SySetUsed(pNames) : 0) + SySetUsed(&pOwner->aInterface); j++) {
+			if(pNames && j < SySetUsed(pNames)) {
+				SyString *pName = (SyString *)SySetAt(pNames, j);
+				pInterface = PH7_VmExtractClass(pVm, pName->zString, pName->nByte, FALSE);
+				if(pInterface == 0) {
+					PH7_VmThrowError(pVm, PH7_CTX_ERR, (pOwner->iFlags & PH7_CLASS_INTERFACE) ?
+						"Call to non-existent base interface '%z'" : "Call to non-existent interface '%z'", pName);
+					return SXERR_INVALID;
+				}
+				if(!(pInterface->iFlags & PH7_CLASS_INTERFACE)) {
+					PH7_VmThrowError(pVm, PH7_CTX_ERR, (pOwner->iFlags & PH7_CLASS_INTERFACE) ?
+						"Interface '%z' cannot inherit from class '%z'" : "Class '%z' cannot implement a class '%z'", &pOwner->sName, pName);
+					return SXERR_INVALID;
+				}
+			} else {
+				pInterface = *(ph7_class **)SySetAt(&pOwner->aInterface, j - (pNames ? SySetUsed(pNames) : 0));
+			}
+			for(k = 0; k < SySetUsed(pSet); k++) {
+				if(*(ph7_class **)SySetAt(pSet, k) == pInterface) {
+					break;
+				}
+			}
+			if(k == SySetUsed(pSet)) {
+				rc = SySetPut(pSet, &pInterface);
+				if(rc != SXRET_OK) {
+					return rc;
+				}
+			}
+		}
+	}
+	return SXRET_OK;
+}
+/*
+ * Interface obligations use exact input identity and the first concrete C3
+ * implementation. Virtual declarations remain contracts, not implementations.
+ */
+static sxi32 ClassValidateInterfaces(ph7_vm *pVm, ph7_class *pClass) {
+	SySet sInterfaces, sRequired;
+	SyHashEntry *pEntry;
+	ph7_class_method *pMeth, *pOther, *pImpl;
+	sxu32 i, j;
+	sxi32 rc;
+	SySetInit(&sInterfaces, &pVm->sAllocator, sizeof(ph7_class *));
+	SySetInit(&sRequired, &pVm->sAllocator, sizeof(ph7_class_method *));
+	rc = PH7_ClassCollectInterfaces(pVm, pClass, &sInterfaces);
+	if(rc != SXRET_OK) {
+		goto done;
+	}
+	for(i = 0; i < SySetUsed(&sInterfaces); i++) {
+		ph7_class *pOwner = *(ph7_class **)SySetAt(&sInterfaces, i);
+		SyHashResetLoopCursor(&pOwner->hMethod);
+		while((pEntry = SyHashGetNextEntry(&pOwner->hMethod)) != 0) {
+			pMeth = (ph7_class_method *)pEntry->pUserData;
+			if(pMeth->sFunc.pClass == pOwner) {
+				rc = SySetPut(&sRequired, &pMeth);
+				if(rc != SXRET_OK) {
+					goto done;
+				}
+			}
+		}
+	}
+	for(i = 0; i < SySetUsed(&sRequired); i++) {
+		pMeth = *(ph7_class_method **)SySetAt(&sRequired, i);
+		for(j = 0; j < i; j++) {
+			pOther = *(ph7_class_method **)SySetAt(&sRequired, j);
+			if(PH7_VmSameSignature(&pMeth->sFunc, &pOther->sFunc) &&
+				(pMeth->sFunc.nType != pOther->sFunc.nType ||
+				((pMeth->sFunc.iFlags ^ pOther->sFunc.iFlags) & VM_FUNC_REF_RETURN))) {
+				PH7_VmThrowError(pVm, PH7_CTX_ERR, "Conflicting interface contract '%z::%z()' inside class '%z'", &pMeth->sFunc.pClass->sName, &pMeth->sFunc.sName, &pClass->sName);
+			}
+		}
+	}
+	for(i = 0; i < SySetUsed(&sRequired); i++) {
+		pMeth = *(ph7_class_method **)SySetAt(&sRequired, i);
+		pImpl = 0;
+		for(j = 0; j < SySetUsed(&pClass->aMro); j++) {
+			ph7_class *pOwner = *(ph7_class **)SySetAt(&pClass->aMro, j);
+			SyHashResetLoopCursor(&pOwner->hMethod);
+			while((pEntry = SyHashGetNextEntry(&pOwner->hMethod)) != 0) {
+				pOther = (ph7_class_method *)pEntry->pUserData;
+				if(pOther->sFunc.pClass == pOwner && PH7_VmSameSignature(&pMeth->sFunc, &pOther->sFunc)) {
+					/* Inherited private helpers are only callable in their own scope. */
+					if(pOther->iProtection == PH7_CLASS_PROT_PRIVATE && pOwner != pClass) {
+						continue;
+					}
+					if(!pImpl || (pOther->iFlags & PH7_CLASS_ATTR_VIRTUAL)) {
+						if(pOther->iProtection != PH7_CLASS_PROT_PUBLIC ||
+							(pOther->iFlags & PH7_CLASS_ATTR_STATIC) || pOther->sFunc.nType != pMeth->sFunc.nType ||
+							((pOther->sFunc.iFlags ^ pMeth->sFunc.iFlags) & VM_FUNC_REF_RETURN)) {
+							PH7_VmThrowError(pVm, PH7_CTX_ERR, "Incompatible interface implementation '%z::%z()' inside class '%z'", &pMeth->sFunc.pClass->sName, &pMeth->sFunc.sName, &pClass->sName);
+						}
+						if(!(pOther->iFlags & PH7_CLASS_ATTR_VIRTUAL)) {
+							pImpl = pOther;
+						}
+					}
+				}
+			}
+		}
+		if(!pImpl && !(pClass->iFlags & PH7_CLASS_VIRTUAL)) {
+			PH7_VmThrowError(pVm, PH7_CTX_ERR, "Method '%z:%z()' must be defined inside class '%z'", &pMeth->sFunc.pClass->sName, &pMeth->sFunc.sName, &pClass->sName);
+		}
+	}
+done:
+	SySetRelease(&sInterfaces);
+	SySetRelease(&sRequired);
+	return rc;
+}
 /*
  * Build [C] + merge(MRO(B1), ..., MRO(Bn), [B1, ..., Bn]).
  * Resolve declarations rather than hDerived: bytecode initialization may not
@@ -515,13 +644,11 @@ PH7_PRIVATE sxi32 PH7_ClassBuildMro(ph7_vm *pVm, ph7_class *pClass) {
 	SySetRelease(&pClass->aMro);
 	pClass->aBase = sBase;
 	pClass->aMro = sMro;
-	pClass->iMroState = 2;
 done:
 	SyMemBackendFree(&pVm->sAllocator, aPos);
 	if(rc != SXRET_OK) {
 		SySetRelease(&sBase);
 		SySetRelease(&sMro);
-		pClass->iMroState = 0;
 	}
 	if(rc == SXRET_OK) {
 		rc = ClassValidateAttributes(pVm, pClass);
@@ -529,6 +656,12 @@ done:
 	if(rc == SXRET_OK) {
 		rc = ClassValidateMethods(pVm, pClass);
 	}
+	if(rc == SXRET_OK) {
+		rc = ClassValidateInterfaces(pVm, pClass);
+	}
+	/* Keep the reentrancy guard through validation. On failure the class owns
+	 * any published arrays, but a retry must rebuild and validate them again. */
+	pClass->iMroState = rc == SXRET_OK ? 2 : 0;
 	return rc;
 }
 /*
@@ -650,7 +783,7 @@ PH7_PRIVATE sxi32 PH7_ClassInherit(ph7_vm *pVm, ph7_class *pSub, ph7_class *pBas
 PH7_PRIVATE sxi32 PH7_ClassInterfaceInherit(ph7_class *pSub, ph7_class *pBase) {
 	ph7_class_method *pMeth;
 	ph7_class_attr *pAttr;
-	SyHashEntry *pEntry;
+	SyHashEntry *pEntry, *pOther;
 	SyString *pName;
 	sxi32 rc;
 	/* Install in the derived hashtable */
@@ -669,20 +802,27 @@ PH7_PRIVATE sxi32 PH7_ClassInterfaceInherit(ph7_class *pSub, ph7_class *pBase) {
 			}
 		}
 	}
+	/* Preserve all overloads for member enumeration. Contracts themselves are
+	 * read from declarations, independently of bytecode initialization order. */
+	if(pSub != pBase) {
 		SyHashResetLoopCursor(&pBase->hMethod);
-	/* Copy methods signature */
 		while((pEntry = SyHashGetNextEntry(&pBase->hMethod)) != 0) {
-		/* Make sure the method are not redeclared in the subclass */
 			pMeth = (ph7_class_method *)pEntry->pUserData;
+			SyHashResetLoopCursor(&pSub->hMethod);
+			while((pOther = SyHashGetNextEntry(&pSub->hMethod)) != 0) {
+				if(pOther->pUserData == pMeth) {
+					break;
+				}
+			}
+			if(!pOther) {
 				pName = &pMeth->sFunc.sName;
-		if(SyHashGet(&pSub->hMethod, (const void *)pName->zString, pName->nByte) == 0) {
-			/* Install the method */
 				rc = SyHashInsert(&pSub->hMethod, (const void *)pName->zString, pName->nByte, pMeth);
 				if(rc != SXRET_OK) {
 					return rc;
 				}
 			}
 		}
+	}
 	/* Mark as subclass */
 	pSub->pBase = pBase;
 	/* All done */
@@ -702,24 +842,11 @@ PH7_PRIVATE sxi32 PH7_ClassInterfaceInherit(ph7_class *pSub, ph7_class *pBase) {
  * error message.
  */
 PH7_PRIVATE sxi32 PH7_ClassImplement(ph7_vm *pVm, ph7_class *pMain, ph7_class *pInterface) {
-	ph7_class_method *pMeth;
+	SXUNUSED(pVm);
-	SyHashEntry *pEntry;
-	SyString *pName;
 	/* Interface constants are not inherited by the implementing class.
 	 * They remain reachable through the interface name only. */
-	SyHashResetLoopCursor(&pInterface->hMethod);
+	/* Contracts were checked against the complete C3 MRO, before mounting. */
-	while((pEntry = SyHashGetNextEntry(&pInterface->hMethod)) != 0) {
+	return SySetPut(&pMain->aInterface, (const void *)&pInterface);
-		pMeth = (ph7_class_method *)pEntry->pUserData;
-		pName = &pMeth->sFunc.sName;
-		if((pEntry = SyHashGet(&pMain->hMethod, (const void *)pName->zString, pName->nByte)) != 0) {
-			continue;
-		} else {
-			PH7_VmThrowError(&(*pVm), PH7_CTX_ERR, "Method '%z:%z()' must be defined inside class '%z'", &pInterface->sName, pName, &pMain->sName);
-		}
-	}
-	/* Install in the interface container */
-	SySetPut(&pMain->aInterface, (const void *)&pInterface);
-	return SXRET_OK;
 }
 /*
  * Create a class instance [i.e: Object in the PHP jargon] at run-time.

engine/vm.c

@@ -6645,14 +6645,16 @@ static int VmQueryInterfaceSet(ph7_class *pClass, SySet *pSet) {
  * Otherwise FALSE is returned.
  */
 static int VmInstanceOf(ph7_vm *pVm, ph7_class *pThis, ph7_class *pClass) {
-	SyHashEntry *pEntry;
+	SySet sInterfaces;
-	ph7_class *pDerived, *pParent;
 	sxi32 rc;
+	if(!pThis || !pClass) {
+		return FALSE;
+	}
 	if(pThis == pClass) {
 		/* Instance of the same class */
 		return TRUE;
 	}
-	if(!(pThis->iFlags & PH7_CLASS_INTERFACE) && !(pClass->iFlags & PH7_CLASS_INTERFACE)) {
+	if(!(pThis->iFlags & PH7_CLASS_INTERFACE)) {
 		sxu32 i;
 		if(PH7_ClassBuildMro(pVm, pThis) != SXRET_OK) {
 			PH7_VmThrowError(pVm, PH7_CTX_ERR, "PH7 is running out-of-memory");
@@ -6662,45 +6664,21 @@ static int VmInstanceOf(ph7_vm *pVm, ph7_class *pThis, ph7_class *pClass) {
 				return TRUE;
 			}
 		}
+		if(!(pClass->iFlags & PH7_CLASS_INTERFACE)) {
 			return FALSE;
 		}
-	/* Check implemented interfaces */
-	rc = VmQueryInterfaceSet(pClass, &pThis->aInterface);
-	if(rc) {
-		return TRUE;
 	}
-	/* Check derived classes */
+	SySetInit(&sInterfaces, &pVm->sAllocator, sizeof(ph7_class *));
-	SyHashResetLoopCursor(&pThis->hDerived);
+	rc = PH7_ClassCollectInterfaces(pVm, pThis, &sInterfaces);
-	while((pEntry = SyHashGetNextEntry(&pThis->hDerived)) != 0) {
+	if(rc != SXRET_OK) {
-		pDerived = (ph7_class *) pEntry->pUserData;
+		SySetRelease(&sInterfaces);
-		if(pDerived == pClass) {
+		PH7_VmMemoryError(pVm);
-			/* Same instance */
-			return TRUE;
-		}
-		/* Check the implemented interfaces */
-		rc = VmQueryInterfaceSet(pClass, &pDerived->aInterface);
-		if(rc) {
-			return TRUE;
-		}
-		/* Check parent classes */
-		pParent = pDerived->pBase;
-		while(pParent) {
-			if(pParent == pClass) {
-				/* Same instance */
-				return TRUE;
-			}
-			/* Check the implemented interfaces */
-			rc = VmQueryInterfaceSet(pClass, &pParent->aInterface);
-			if(rc) {
-				return TRUE;
-			}
-			/* Point to the parent class */
-			pParent = pParent->pBase;
-		}
-	}
-	/* Not an instance of the the given class */
 		return FALSE;
 	}
+	rc = VmQueryInterfaceSet(pClass, &sInterfaces);
+	SySetRelease(&sInterfaces);
+	return rc;
+}
 /*
  * This function returns TRUE if the given class (first argument)
  * is a subclass of the main class (second argument).

include/ph7int.h

@@ -1774,6 +1774,7 @@ PH7_PRIVATE sxi32 PH7_ClassInstallAttr(ph7_gen_state *pGen, ph7_class *pClass, p
 PH7_PRIVATE sxi32 PH7_ClassInstallMethod(ph7_class *pClass, ph7_class_method *pMeth);
 PH7_PRIVATE sxi32 PH7_ClassInherit(ph7_vm *pVm, ph7_class *pSub, ph7_class *pBase);
 PH7_PRIVATE sxi32 PH7_ClassBuildMro(ph7_vm *pVm, ph7_class *pClass);
+PH7_PRIVATE sxi32 PH7_ClassCollectInterfaces(ph7_vm *pVm, ph7_class *pClass, SySet *pSet);
 PH7_PRIVATE sxi32 PH7_ClassInterfaceInherit(ph7_class *pSub, ph7_class *pBase);
 PH7_PRIVATE sxi32 PH7_ClassImplement(ph7_vm *pVm, ph7_class *pMain, ph7_class *pInterface);
 PH7_PRIVATE ph7_class_instance *PH7_NewClassInstance(ph7_vm *pVm, ph7_class *pClass);