Fix lifetime dependence inference for multi-arg functions

Author: meg-gupta

lib/Sema/LifetimeDependence.cpp

@@ -18,6 +18,7 @@
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/Type.h"
 #include "swift/AST/TypeRepr.h"
+#include "swift/Basic/Defer.h"
 
 namespace swift {
 std::string LifetimeDependenceInfo::getString() const {
@@ -327,6 +328,9 @@ LifetimeDependenceInfo::infer(AbstractFunctionDecl *afd, Type resultType) {
   unsigned paramIndex = 0;
   bool hasParamError = false;
   for (auto *param : *afd->getParameters()) {
+    SWIFT_DEFER {
+      paramIndex++;
+    };
     Type paramTypeInContext =
         afd->mapTypeIntoContext(param->getInterfaceType());
 
@@ -351,8 +355,6 @@ LifetimeDependenceInfo::infer(AbstractFunctionDecl *afd, Type resultType) {
     candidateParam = param;
     lifetimeDependenceInfo = LifetimeDependenceInfo::getForParamIndex(
         afd, paramIndex + 1, param->getValueOwnership());
-
-    paramIndex++;
   }
   if (cd && cd->isImplicit()) {
     diags.diagnose(cd->getLoc(),

test/SIL/implicit_lifetime_dependence.swift

@@ -25,7 +25,7 @@ struct BufferView : ~Escapable {
     self.ptr = otherBV.ptr
     self.c = otherBV.c
   }
-// CHECK: sil hidden @$s28implicit_lifetime_dependence10BufferViewVyACSWYls_SaySiGhtcfC : $@convention(method) (UnsafeRawBufferPointer, @guaranteed Array<Int>, @thin BufferView.Type) -> _scope(1) @owned BufferView {
+// CHECK: sil hidden @$s28implicit_lifetime_dependence10BufferViewVyACSW_SaySiGhYlstcfC : $@convention(method) (UnsafeRawBufferPointer, @guaranteed Array<Int>, @thin BufferView.Type) -> _scope(2) @owned BufferView {
   init(_ ptr: UnsafeRawBufferPointer, _ a: borrowing Array<Int>) {
     self.ptr = ptr
     self.c = a.count
@@ -126,7 +126,7 @@ struct GenericBufferView<Element> : ~Escapable {
   let baseAddress: Pointer
   let count: Int
 
-// CHECK: sil hidden @$s28implicit_lifetime_dependence17GenericBufferViewV11baseAddress5count9dependsOnACyxGSVYls_Siqd__htclufC : $@convention(method) <Element><Storage> (UnsafeRawPointer, Int, @in_guaranteed Storage, @thin GenericBufferView<Element>.Type) -> _scope(1) @owned GenericBufferView<Element> {
+// CHECK: sil hidden @$s28implicit_lifetime_dependence17GenericBufferViewV11baseAddress5count9dependsOnACyxGSV_Siqd__hYlstclufC : $@convention(method) <Element><Storage> (UnsafeRawPointer, Int, @in_guaranteed Storage, @thin GenericBufferView<Element>.Type) -> _scope(3) @owned GenericBufferView<Element> {
   init<Storage>(baseAddress: Pointer,
                 count: Int,
                 dependsOn: borrowing Storage) {

test/SIL/lifetime_dependence_buffer_view_test.swift

@@ -2,8 +2,7 @@
 // RUN:   -disable-experimental-parser-round-trip \
 // RUN:   -enable-experimental-feature NonescapableTypes \
 // RUN:   -enable-experimental-feature NoncopyableGenerics \
-// RUN:   -enable-experimental-lifetime-dependence-inference \ 
-// RUN:   -Xllvm -enable-lifetime-dependence-diagnostics
+// RUN:   -enable-experimental-lifetime-dependence-inference
 
 // REQUIRES: asserts
 // REQUIRES: swift_in_compiler
@@ -62,7 +61,7 @@ public struct BufferView<Element> : ~Escapable {
   let start: BufferViewIndex<Element>
   public let count: Int
   private var baseAddress: UnsafeRawPointer { start._rawValue }
-  
+// TODO: Enable diagnostics once this initializer's store to temporary is handled  
 // CHECK: sil @$s31lifetime_dependence_scope_fixup10BufferViewV11baseAddress5count9dependsOnACyxGSVYls_Siqd__htclufC : $@convention(method) <Element><Owner> (UnsafeRawPointer, Int, @in_guaranteed Owner, @thin BufferView<Element>.Type) -> _scope(1) @owned BufferView<Element> {
   public init<Owner>(
       baseAddress: UnsafeRawPointer,