CL Driver: Add support for /Zp

[majnemer]

Summary

CL's /Zp flag is analogous to GCC's -fpack-struct, it controls the
default maximum alignment of records.

[hans]

Looks great to me.

(Ultra nit: I'd prefix the commit message with "clang-cl:" instead of "CL Driver".)

[majnemer]

Closed by commit rL213958 (authored by @majnemer).

cfe/trunk/include/clang/Driver/CLCompatOptions.td

 def _SLASH_w_flag : CLFlag<"w">, HelpText<"Disable all warnings">, Alias<w>;
 def _SLASH_wd4005 : CLFlag<"wd4005">, Alias<W_Joined>,
   AliasArgs<["no-macro-redefined"]>;
 def _SLASH_vd : CLJoined<"vd">, HelpText<"Control vtordisp placement">,
   Alias<vtordisp_mode_EQ>;
 def _SLASH_Z7 : CLFlag<"Z7">, Alias<gline_tables_only>;
 def _SLASH_Zi : CLFlag<"Zi">, HelpText<"Enable debug information">,
   Alias<gline_tables_only>;
+def _SLASH_Zp : CLJoined<"Zp">,
+  HelpText<"Specify the default maximum struct packing alignment">,
+  Alias<fpack_struct_EQ>;
+def _SLASH_Zp_flag : CLFlag<"Zp">,
+  HelpText<"Set the default maximum struct packing alignment to 1">,
+  Alias<fpack_struct_EQ>, AliasArgs<["1"]>;
 def _SLASH_Zs : CLFlag<"Zs">, HelpText<"Syntax-check only">,
   Alias<fsyntax_only>;
 
 
 // Non-aliases:
 
 def _SLASH_arch : CLCompileJoined<"arch:">,
   HelpText<"Set architecture for code generation">;

 def _SLASH_Yl : CLJoined<"Yl">;
 def _SLASH_Yu : CLJoined<"Yu">;
 def _SLASH_Za : CLFlag<"Za">;
 def _SLASH_Zc : CLJoined<"Zc:">;
 def _SLASH_Ze : CLFlag<"Ze">;
 def _SLASH_Zg : CLFlag<"Zg">;
 def _SLASH_ZI : CLFlag<"ZI">;
 def _SLASH_Zl : CLFlag<"Zl">;
-def _SLASH_Zp : CLJoined<"Zp">;
 def _SLASH_ZW : CLJoined<"ZW">;

cfe/trunk/test/Driver/cl-options.c

 // WX: -Werror
 
 // RUN: %clang_cl /WX- -### -- %s 2>&1 | FileCheck -check-prefix=WX_ %s
 // WX_: -Wno-error
 
 // RUN: %clang_cl /w -### -- %s 2>&1 | FileCheck -check-prefix=w %s
 // w: -w
 
+// RUN: %clang_cl /Zp -### -- %s 2>&1 | FileCheck -check-prefix=ZP %s
+// ZP: -fpack-struct=1
+
+// RUN: %clang_cl /Zp2 -### -- %s 2>&1 | FileCheck -check-prefix=ZP2 %s
+// ZP2: -fpack-struct=2
+
 // RUN: %clang_cl /Zs -### -- %s 2>&1 | FileCheck -check-prefix=Zs %s
 // Zs: -fsyntax-only
 
 // RUN: %clang_cl /FIasdf.h -### -- %s 2>&1 | FileCheck -check-prefix=FI %s
 // FI: "-include" "asdf.h"
 
 // RUN: %clang_cl /FI asdf.h -### -- %s 2>&1 | FileCheck -check-prefix=FI_ %s
 // FI_: "-include" "asdf.h"

 // RUN:     /Za \
 // RUN:     /Zc:auto \
 // RUN:     /Zc:wchar_t- \
 // RUN:     /Ze \
 // RUN:     /Zg \
 // RUN:     /Zi \
 // RUN:     /ZI \
 // RUN:     /Zl \
-// RUN:     /Zp \
-// RUN:     /Zp1 \
 // RUN:     /ZW:nostdlib \
 // RUN:     -- %s 2>&1
 
 // We support -Xclang for forwarding options to cc1.
 // RUN: %clang_cl -Xclang hellocc1 -### -- %s 2>&1 | FileCheck -check-prefix=Xclang %s
 // Xclang: "-cc1"
 // Xclang: "hellocc1"