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>

4 files changed, 18 insertions, 0 deletions

diff --git a/Source/cmGlobalBorlandMakefileGenerator.h b/Source/cmGlobalBorlandMakefileGenerator.h
index bd3db3e..70004ea 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 284f5d1..ec2e1df 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 23e60a1..d5350ef 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 6ca386c..ec1d2c4 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);