Add Sema diagnostic to ban _copy/_consume lifetime dependence on Escapable types

Author: meg-gupta

include/swift/AST/DiagnosticsSema.def

@@ -7832,6 +7832,9 @@ ERROR(lifetime_dependence_cannot_infer_no_candidates, none,
 ERROR(lifetime_dependence_ctor_non_self_or_nil_return, none,
       "expected nil or self as return values in an initializer with "
        "lifetime dependent specifiers", ())
+ERROR(lifetime_dependence_cannot_use_infer, none,
+       "invalid use of %0 lifetime dependence on Escapable type",
+       (StringRef))
 
 //===----------------------------------------------------------------------===//
 //                             MARK: Transferring

lib/Sema/LifetimeDependence.cpp

@@ -116,7 +116,7 @@ LifetimeDependenceInfo::fromTypeRepr(AbstractFunctionDecl *afd, Type resultType,
   SmallBitVector scopeLifetimeParamIndices(capacity);
 
   auto updateLifetimeDependenceInfo = [&](LifetimeDependenceSpecifier specifier,
-                                          unsigned paramIndexToSet,
+                                          unsigned paramIndexToSet, Type type,
                                           ValueOwnership ownership) {
     auto loc = specifier.getLoc();
     auto kind = specifier.getLifetimeDependenceKind();
@@ -148,6 +148,14 @@ LifetimeDependenceInfo::fromTypeRepr(AbstractFunctionDecl *afd, Type resultType,
                      getOwnershipSpelling(ownership));
       return true;
     }
+    if (kind == LifetimeDependenceKind::Consume ||
+        kind == LifetimeDependenceKind::Copy) {
+      if (type->isEscapable()) {
+        diags.diagnose(loc, diag::lifetime_dependence_cannot_use_infer,
+                       specifier.getLifetimeDependenceKindString());
+        return true;
+      }
+    }
     if (inheritLifetimeParamIndices.test(paramIndexToSet) ||
         scopeLifetimeParamIndices.test(paramIndexToSet)) {
       diags.diagnose(loc, diag::lifetime_dependence_duplicate_param_id);
@@ -168,17 +176,20 @@ LifetimeDependenceInfo::fromTypeRepr(AbstractFunctionDecl *afd, Type resultType,
     switch (specifier.getSpecifierKind()) {
     case LifetimeDependenceSpecifier::SpecifierKind::Named: {
       bool foundParamName = false;
-      unsigned paramIndexToSet = 1;
+      unsigned paramIndex = 0;
       for (auto *param : *afd->getParameters()) {
         if (param->getParameterName() == specifier.getName()) {
           foundParamName = true;
-          if (updateLifetimeDependenceInfo(specifier, paramIndexToSet,
-                                           param->getValueOwnership())) {
+          if (updateLifetimeDependenceInfo(
+                  specifier, paramIndex + 1,
+                  afd->mapTypeIntoContext(
+                      param->toFunctionParam().getParameterType()),
+                  param->getValueOwnership())) {
             return llvm::None;
           }
           break;
         }
-        paramIndexToSet++;
+        paramIndex++;
       }
       if (!foundParamName) {
         diags.diagnose(specifier.getLoc(),
@@ -189,29 +200,23 @@ LifetimeDependenceInfo::fromTypeRepr(AbstractFunctionDecl *afd, Type resultType,
       break;
     }
     case LifetimeDependenceSpecifier::SpecifierKind::Ordered: {
-      auto paramIndex = specifier.getIndex();
-      if (paramIndex > afd->getParameters()->size()) {
+      auto index = specifier.getIndex();
+      if (index > afd->getParameters()->size()) {
         diags.diagnose(specifier.getLoc(),
-                       diag::lifetime_dependence_invalid_param_index,
-                       paramIndex);
+                       diag::lifetime_dependence_invalid_param_index, index);
         return llvm::None;
       }
-      if (paramIndex == 0) {
-        if (!afd->hasImplicitSelfDecl()) {
-          diags.diagnose(specifier.getLoc(),
-                         diag::lifetime_dependence_invalid_self);
+      if (index != 0) {
+        auto param = afd->getParameters()->get(index - 1);
+        auto ownership = param->getValueOwnership();
+        auto type = afd->mapTypeIntoContext(
+            param->toFunctionParam().getParameterType());
+        if (updateLifetimeDependenceInfo(specifier, index, type, ownership)) {
           return llvm::None;
         }
+        break;
       }
-      auto ownership =
-          paramIndex == 0
-              ? afd->getImplicitSelfDecl()->getValueOwnership()
-              : afd->getParameters()->get(paramIndex - 1)->getValueOwnership();
-      if (updateLifetimeDependenceInfo(
-              specifier, /*paramIndexToSet*/ specifier.getIndex(), ownership)) {
-        return llvm::None;
-      }
-      break;
+      LLVM_FALLTHROUGH;
     }
     case LifetimeDependenceSpecifier::SpecifierKind::Self: {
       if (!afd->hasImplicitSelfDecl()) {
@@ -221,6 +226,7 @@ LifetimeDependenceInfo::fromTypeRepr(AbstractFunctionDecl *afd, Type resultType,
       }
       if (updateLifetimeDependenceInfo(
               specifier, /*selfIndex*/ 0,
+              afd->getImplicitSelfDecl()->getTypeInContext(),
               afd->getImplicitSelfDecl()->getValueOwnership())) {
         return llvm::None;
       }