Recommit r308327 2nd time: Add a warning for missing

'#pragma pack (pop)' and suspicious uses of '#pragma pack' in included files

The first recommit (r308441) caused a "non-default #pragma pack value might
change the alignment of struct or union members in the included file" warning
in LLVM itself. This recommit tweaks the added warning to avoid warnings for
#includes that don't have any records that are affected by the non-default
alignment. This tweak avoids the previously emitted warning in LLVM.

Original message:

This commit adds a new -Wpragma-pack warning. It warns in the following cases:

- When a translation unit is missing terminating #pragma pack (pop) directives.
- When entering an included file if the current alignment value as determined
  by '#pragma pack' directives is different from the default alignment value.
- When leaving an included file that changed the state of the current alignment
  value.

rdar://10184173

Differential Revision: https://reviews.llvm.org/D35484

llvm-svn: 309106

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index cae99e8bf0a..eb49a90d721 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3382,6 +3382,7 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
         PragmaPackStackEntry Entry;
         Entry.Value = Record[Idx++];
         Entry.Location = ReadSourceLocation(F, Record[Idx++]);
+        Entry.PushLocation = ReadSourceLocation(F, Record[Idx++]);
         PragmaPackStrings.push_back(ReadString(Record, Idx));
         Entry.SlotLabel = PragmaPackStrings.back();
         PragmaPackStack.push_back(Entry);
@@ -7570,13 +7571,14 @@ void ASTReader::UpdateSema() {
              "Expected a default alignment value");
       SemaObj->PackStack.Stack.emplace_back(
           PragmaPackStack.front().SlotLabel, SemaObj->PackStack.CurrentValue,
-          SemaObj->PackStack.CurrentPragmaLocation);
+          SemaObj->PackStack.CurrentPragmaLocation,
+          PragmaPackStack.front().PushLocation);
       DropFirst = true;
     }
     for (const auto &Entry :
          llvm::makeArrayRef(PragmaPackStack).drop_front(DropFirst ? 1 : 0))
       SemaObj->PackStack.Stack.emplace_back(Entry.SlotLabel, Entry.Value,
-                                            Entry.Location);
+                                            Entry.Location, Entry.PushLocation);
     if (PragmaPackCurrentLocation.isInvalid()) {
       assert(*PragmaPackCurrentValue == SemaObj->PackStack.DefaultValue &&
              "Expected a default alignment value");