From 6d74e7870b8804a5af0bc395a9fbb45c1b3d26a4 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 15 Mar 2016 10:15:53 -0400
Subject: [PATCH] Ninja: Add dependencies on system-provided header files
 (#14914)

When system-provided packages are upgraded we must re-compile sources
depending on their headers.  Use `-MD` instead of `-MMD` so that the
generated depfiles do not exclude system headers.

Suggested-by: Jussi Judin
---
 Help/release/dev/ninja-depfile-system-headers.rst | 5 +++++
 Modules/Compiler/GNU.cmake                        | 2 +-
 Modules/Compiler/Intel-C.cmake                    | 2 +-
 Modules/Compiler/Intel-CXX.cmake                  | 2 +-
 Modules/Compiler/QCC.cmake                        | 2 +-
 5 files changed, 9 insertions(+), 4 deletions(-)
 create mode 100644 Help/release/dev/ninja-depfile-system-headers.rst

diff --git a/Help/release/dev/ninja-depfile-system-headers.rst b/Help/release/dev/ninja-depfile-system-headers.rst
new file mode 100644
index 000000000..7033cef6f
--- /dev/null
+++ b/Help/release/dev/ninja-depfile-system-headers.rst
@@ -0,0 +1,5 @@
+ninja-depfile-system-headers
+----------------------------
+
+* The :generator:`Ninja` generator now includes system header files in build
+  dependencies to ensure correct re-builds when system packages are updated.
diff --git a/Modules/Compiler/GNU.cmake b/Modules/Compiler/GNU.cmake
index d1ca85e3d..c2d393dc8 100644
--- a/Modules/Compiler/GNU.cmake
+++ b/Modules/Compiler/GNU.cmake
@@ -41,7 +41,7 @@ macro(__compiler_gnu lang)
     # distcc does not transform -o to -MT when invoking the preprocessor
     # internally, as it ought to.  Work around this bug by setting -MT here
     # even though it isn't strictly necessary.
-    set(CMAKE_DEPFILE_FLAGS_${lang} "-MMD -MT <OBJECT> -MF <DEPFILE>")
+    set(CMAKE_DEPFILE_FLAGS_${lang} "-MD -MT <OBJECT> -MF <DEPFILE>")
   endif()
 
   # Initial configuration flags.
diff --git a/Modules/Compiler/Intel-C.cmake b/Modules/Compiler/Intel-C.cmake
index dfba4b2ce..77363eb9c 100644
--- a/Modules/Compiler/Intel-C.cmake
+++ b/Modules/Compiler/Intel-C.cmake
@@ -6,7 +6,7 @@ set(CMAKE_C_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG")
 set(CMAKE_C_FLAGS_RELEASE_INIT "-O3 -DNDEBUG")
 set(CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -DNDEBUG")
 
-set(CMAKE_DEPFILE_FLAGS_C "-MMD -MT <OBJECT> -MF <DEPFILE>")
+set(CMAKE_DEPFILE_FLAGS_C "-MD -MT <OBJECT> -MF <DEPFILE>")
 
 set(CMAKE_C_CREATE_PREPROCESSED_SOURCE "<CMAKE_C_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
 set(CMAKE_C_CREATE_ASSEMBLY_SOURCE "<CMAKE_C_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
diff --git a/Modules/Compiler/Intel-CXX.cmake b/Modules/Compiler/Intel-CXX.cmake
index 794769527..02c636cc4 100644
--- a/Modules/Compiler/Intel-CXX.cmake
+++ b/Modules/Compiler/Intel-CXX.cmake
@@ -6,7 +6,7 @@ set(CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG")
 set(CMAKE_CXX_FLAGS_RELEASE_INIT "-O3 -DNDEBUG")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -DNDEBUG")
 
-set(CMAKE_DEPFILE_FLAGS_CXX "-MMD -MT <OBJECT> -MF <DEPFILE>")
+set(CMAKE_DEPFILE_FLAGS_CXX "-MD -MT <OBJECT> -MF <DEPFILE>")
 
 set(CMAKE_CXX_CREATE_PREPROCESSED_SOURCE "<CMAKE_CXX_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
 set(CMAKE_CXX_CREATE_ASSEMBLY_SOURCE "<CMAKE_CXX_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
diff --git a/Modules/Compiler/QCC.cmake b/Modules/Compiler/QCC.cmake
index 76477e4bb..f69c7bda0 100644
--- a/Modules/Compiler/QCC.cmake
+++ b/Modules/Compiler/QCC.cmake
@@ -20,5 +20,5 @@ macro(__compiler_qcc lang)
   set(CMAKE_${lang}_COMPILE_OPTIONS_TARGET "-V")
 
   set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-Wp,-isystem,")
-  set(CMAKE_DEPFILE_FLAGS_${lang} "-Wc,-MMD,<DEPFILE>,-MT,<OBJECT>,-MF,<DEPFILE>")
+  set(CMAKE_DEPFILE_FLAGS_${lang} "-Wc,-MD,<DEPFILE>,-MT,<OBJECT>,-MF,<DEPFILE>")
 endmacro()