Add a warning for missing '#pragma pack (pop)' and suspicious uses

of '#pragma pack' in included files

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


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@308327 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 39 insertions, 6 deletions

diff --git a/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td
index 3a0564806b..adb71fa9d5 100644
--- a/include/clang/Basic/DiagnosticGroups.td
+++ b/include/clang/Basic/DiagnosticGroups.td
@@ -467,8 +467,9 @@ def IgnoredPragmaIntrinsic : DiagGroup<"ignored-pragma-intrinsic">;
 def UnknownPragmas : DiagGroup<"unknown-pragmas">;
 def IgnoredPragmas : DiagGroup<"ignored-pragmas", [IgnoredPragmaIntrinsic]>;
 def PragmaClangAttribute : DiagGroup<"pragma-clang-attribute">;
+def PragmaPack : DiagGroup<"pragma-pack">;
 def Pragmas : DiagGroup<"pragmas", [UnknownPragmas, IgnoredPragmas,
-                                    PragmaClangAttribute]>;
+                                    PragmaClangAttribute, PragmaPack]>;
 def UnknownWarningOption : DiagGroup<"unknown-warning-option">;
 def NSobjectAttribute : DiagGroup<"NSObject-attribute">;
 def IndependentClassAttribute : DiagGroup<"IndependentClass-attribute">;
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 09ad1c5b2a..aeeef5cae6 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -712,6 +712,16 @@ def err_pragma_options_align_mac68k_target_unsupported : Error<
 def warn_pragma_pack_invalid_alignment : Warning<
   "expected #pragma pack parameter to be '1', '2', '4', '8', or '16'">,
   InGroup<IgnoredPragmas>;
+def warn_pragma_pack_non_default_at_include : Warning<
+  "non-default #pragma pack value might change the alignment of struct or "
+  "union members in the included file">, InGroup<PragmaPack>;
+def warn_pragma_pack_modified_after_include : Warning<
+  "the current #pragma pack aligment value is modified in the included "
+  "file">, InGroup<PragmaPack>;
+def warn_pragma_pack_no_pop_eof : Warning<"unterminated "
+  "'#pragma pack (push, ...)' at end of file">, InGroup<PragmaPack>;
+def note_pragma_pack_here : Note<
+  "previous '#pragma pack' directive that modifies alignment is here">;
 // Follow the Microsoft implementation.
 def warn_pragma_pack_show : Warning<"value of #pragma pack(show) == %0">;
 def warn_pragma_pack_pop_identifer_and_alignment : Warning<
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 49d626755e..44c1124a69 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -208,6 +208,7 @@ namespace sema {
   class FunctionScopeInfo;
   class LambdaScopeInfo;
   class PossiblyUnreachableDiag;
+  class SemaPPCallbacks;
   class TemplateDeductionInfo;
 }
 
@@ -381,11 +382,12 @@ public:
       llvm::StringRef StackSlotLabel;
       ValueType Value;
       SourceLocation PragmaLocation;
-      Slot(llvm::StringRef StackSlotLabel,
-           ValueType Value,
-           SourceLocation PragmaLocation)
-        : StackSlotLabel(StackSlotLabel), Value(Value),
-          PragmaLocation(PragmaLocation) {}
+      SourceLocation PragmaPushLocation;
+      Slot(llvm::StringRef StackSlotLabel, ValueType Value,
+           SourceLocation PragmaLocation, SourceLocation PragmaPushLocation)
+          : StackSlotLabel(StackSlotLabel), Value(Value),
+            PragmaLocation(PragmaLocation),
+            PragmaPushLocation(PragmaPushLocation) {}
     };
     void Act(SourceLocation PragmaLocation,
              PragmaMsStackAction Action,
@@ -416,6 +418,8 @@ public:
     explicit PragmaStack(const ValueType &Default)
         : DefaultValue(Default), CurrentValue(Default) {}
 
+    bool hasValue() const { return CurrentValue != DefaultValue; }
+
     SmallVector<Slot, 2> Stack;
     ValueType DefaultValue; // Value used for PSK_Reset action.
     ValueType CurrentValue;
@@ -437,6 +441,8 @@ public:
   // Sentinel to represent when the stack is set to mac68k alignment.
   static const unsigned kMac68kAlignmentSentinel = ~0U;
   PragmaStack<unsigned> PackStack;
+  // The current #pragma pack values and locations at each #include.
+  SmallVector<std::pair<unsigned, SourceLocation>, 8> PackIncludeStack;
   // Segment #pragmas.
   PragmaStack<StringLiteral *> DataSegStack;
   PragmaStack<StringLiteral *> BSSSegStack;
@@ -8185,6 +8191,15 @@ public:
   void ActOnPragmaPack(SourceLocation PragmaLoc, PragmaMsStackAction Action,
                        StringRef SlotLabel, Expr *Alignment);
 
+  enum class PragmaPackDiagnoseKind {
+    NonDefaultStateAtInclude,
+    ChangedStateAtExit
+  };
+
+  void DiagnoseNonDefaultPragmaPack(PragmaPackDiagnoseKind Kind,
+                                    SourceLocation IncludeLoc);
+  void DiagnoseUnterminatedPragmaPack();
+
   /// ActOnPragmaMSStruct - Called on well formed \#pragma ms_struct [on|off].
   void ActOnPragmaMSStruct(PragmaMSStructKind Kind);
 
@@ -10378,6 +10393,12 @@ private:
 
   IdentifierInfo *Ident_NSError = nullptr;
 
+  /// \brief The handler for the FileChanged preprocessor events.
+  ///
+  /// Used for diagnostics that implement custom semantic analysis for #include
+  /// directives, like -Wpragma-pack.
+  sema::SemaPPCallbacks *SemaPPCallbackHandler;
+
 protected:
   friend class Parser;
   friend class InitializationSequence;
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index eafa051758..19f0b81913 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -825,6 +825,7 @@ private:
   struct PragmaPackStackEntry {
     unsigned Value;
     SourceLocation Location;
+    SourceLocation PushLocation;
     StringRef SlotLabel;
   };
   llvm::SmallVector<PragmaPackStackEntry, 2> PragmaPackStack;