Recommit r308327: 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

llvm-svn: 308441

4 files changed, 78 insertions, 0 deletions

diff --git a/clang/test/Sema/Inputs/pragma-pack1.h b/clang/test/Sema/Inputs/pragma-pack1.h
new file mode 100644
index 00000000000..40e7ad18b2c
--- /dev/null
+++ b/clang/test/Sema/Inputs/pragma-pack1.h
@@ -0,0 +1,23 @@
+
+#ifdef SET_FIRST_HEADER
+#pragma pack (16)
+#ifndef SET_SECOND_HEADER
+// expected-note@-2 2 {{previous '#pragma pack' directive that modifies alignment is here}}
+#else
+// expected-note@-4 1 {{previous '#pragma pack' directive that modifies alignment is here}}
+#endif
+// expected-warning@+3 {{non-default #pragma pack value might change the alignment of struct or union members in the included file}}
+#endif
+
+#include "pragma-pack2.h"
+
+#ifdef SET_SECOND_HEADER
+// expected-warning@-3 {{the current #pragma pack aligment value is modified in the included file}}
+#endif
+
+#ifdef PUSH_POP_FIRST_HEADER
+// This is fine, we don't change the current value.
+#pragma pack (push, 4)
+
+#pragma pack (pop)
+#endif
diff --git a/clang/test/Sema/Inputs/pragma-pack2.h b/clang/test/Sema/Inputs/pragma-pack2.h
new file mode 100644
index 00000000000..11036133a15
--- /dev/null
+++ b/clang/test/Sema/Inputs/pragma-pack2.h
@@ -0,0 +1,6 @@
+
+#ifdef SET_SECOND_HEADER
+#pragma pack (8) // expected-note 2 {{previous '#pragma pack' directive that modifies alignment is here}}
+#endif
+
+struct S { int x; };
diff --git a/clang/test/Sema/pragma-pack.c b/clang/test/Sema/pragma-pack.c
index e93ce42148c..84a946368ff 100644
--- a/clang/test/Sema/pragma-pack.c
+++ b/clang/test/Sema/pragma-pack.c
@@ -25,3 +25,8 @@
 #pragma pack(pop, 16)
 /* expected-warning {{value of #pragma pack(show) == 16}} */ #pragma pack(show)
 
+
+// Warn about unbalanced pushes.
+#pragma pack (push,4) // expected-warning {{unterminated '#pragma pack (push, ...)' at end of file}}
+#pragma pack (push)   // expected-warning {{unterminated '#pragma pack (push, ...)' at end of file}}
+#pragma pack ()
diff --git a/clang/test/Sema/suspicious-pragma-pack.c b/clang/test/Sema/suspicious-pragma-pack.c
new file mode 100644
index 00000000000..10c41671028
--- /dev/null
+++ b/clang/test/Sema/suspicious-pragma-pack.c
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DSAFE -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DSAFE -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DPUSH_SET_HERE -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DRESET_HERE -DSAFE -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DSET_FIRST_HEADER -DWARN_MODIFIED_HEADER -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DRESET_HERE -DSET_FIRST_HEADER -DWARN_MODIFIED_HEADER -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DPUSH_SET_HERE -DSET_FIRST_HEADER -DWARN_MODIFIED_HEADER -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DPUSH_SET_HERE -DSET_SECOND_HEADER -DWARN_MODIFIED_HEADER -verify %s
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_HERE -DPUSH_SET_HERE -DSET_FIRST_HEADER -DSET_SECOND_HEADER -DWARN_MODIFIED_HEADER -verify %s
+
+// RUN: %clang_cc1 -triple i686-apple-darwin9 -fsyntax-only -I %S/Inputs -DPUSH_POP_FIRST_HEADER -DSAFE -verify %s
+
+
+#ifdef SAFE
+// expected-no-diagnostics
+#endif
+
+#ifdef PUSH_HERE
+#pragma pack (push)
+#endif
+
+#ifdef PUSH_SET_HERE
+#pragma pack (push, 4) // expected-note {{previous '#pragma pack' directive that modifies alignment is here}}
+// expected-warning@+8 {{non-default #pragma pack value might change the alignment of struct or union members in the included file}}
+#endif
+
+#ifdef RESET_HERE
+#pragma pack (4)
+#pragma pack () // no warning after reset as the value is default.
+#endif
+
+#include "pragma-pack1.h"
+
+#ifdef WARN_MODIFIED_HEADER
+// expected-warning@-3 {{the current #pragma pack aligment value is modified in the included file}}
+#endif
+
+#ifdef PUSH_SET_HERE
+#pragma pack (pop)
+#endif
+
+#ifdef PUSH_HERE
+#pragma pack (pop)
+#endif