From bd11de085757f170c5880d99291048b9f512a120 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Wed, 18 Dec 2013 16:39:11 -0500
Subject: [PATCH] Makefile: Allow "gmake target1 target2 -j" (#14312)

Add the .NOTPARALLEL target to each local Makefile command-line
interface entry point file so that even with -j we launch only
one "make -f Makefile2" at a time.  The actual build rules
in Makefile2 and lower will still run in parallel.

Do not add .NOTPARALLEL for Borland or Watcom make tools because
they do not tolerate it.  Other make tools that do not understand
.NOTPARALLEL will not be hurt.

Suggested-by: Robert Luberda <robert-cmake@debian.org>
---
 Source/cmGlobalBorlandMakefileGenerator.h |  2 ++
 Source/cmGlobalUnixMakefileGenerator3.h   |  3 +++
 Source/cmGlobalWatcomWMakeGenerator.h     |  2 ++
 Source/cmLocalUnixMakefileGenerator3.cxx  | 11 +++++++++++
 4 files changed, 18 insertions(+)

diff --git a/Source/cmGlobalBorlandMakefileGenerator.h b/Source/cmGlobalBorlandMakefileGenerator.h
index bd3db3eae..70004ea3a 100644
--- a/Source/cmGlobalBorlandMakefileGenerator.h
+++ b/Source/cmGlobalBorlandMakefileGenerator.h
@@ -44,6 +44,8 @@ public:
    */
   virtual void EnableLanguage(std::vector<std::string>const& languages,
                               cmMakefile *, bool optional);
+
+  virtual bool AllowNotParallel() const { return false; }
 };
 
 #endif
diff --git a/Source/cmGlobalUnixMakefileGenerator3.h b/Source/cmGlobalUnixMakefileGenerator3.h
index 284f5d1f7..ec2e1df8d 100644
--- a/Source/cmGlobalUnixMakefileGenerator3.h
+++ b/Source/cmGlobalUnixMakefileGenerator3.h
@@ -125,6 +125,9 @@ public:
                             const std::string &workingDirectory,
                             const std::string &compileCommand);
 
+  /** Does the make tool tolerate .NOTPARALLEL? */
+  virtual bool AllowNotParallel() const { return true; }
+
 protected:
   void WriteMainMakefile2();
   void WriteMainCMakefile();
diff --git a/Source/cmGlobalWatcomWMakeGenerator.h b/Source/cmGlobalWatcomWMakeGenerator.h
index 23e60a1fc..d5350efd1 100644
--- a/Source/cmGlobalWatcomWMakeGenerator.h
+++ b/Source/cmGlobalWatcomWMakeGenerator.h
@@ -43,6 +43,8 @@ public:
    */
   virtual void EnableLanguage(std::vector<std::string>const& languages,
                               cmMakefile *, bool optional);
+
+  virtual bool AllowNotParallel() const { return false; }
 };
 
 #endif
diff --git a/Source/cmLocalUnixMakefileGenerator3.cxx b/Source/cmLocalUnixMakefileGenerator3.cxx
index 6ca386c07..ec1d2c451 100644
--- a/Source/cmLocalUnixMakefileGenerator3.cxx
+++ b/Source/cmLocalUnixMakefileGenerator3.cxx
@@ -1686,6 +1686,17 @@ void cmLocalUnixMakefileGenerator3
                       "default_target",
                       depends,
                       no_commands, true);
+
+  // Help out users that try "gmake target1 target2 -j".
+  cmGlobalUnixMakefileGenerator3* gg =
+    static_cast<cmGlobalUnixMakefileGenerator3*>(this->GlobalGenerator);
+  if(gg->AllowNotParallel())
+    {
+    std::vector<std::string> no_depends;
+    this->WriteMakeRule(ruleFileStream,
+      "Allow only one \"make -f Makefile2\" at a time, but pass parallelism.",
+      ".NOTPARALLEL", no_depends, no_commands, true);
+    }
   }
 
   this->WriteSpecialTargetsTop(ruleFileStream);