Ninja: don't use shell when cmake is called directly

When linking with cmake and vs_link_* the command line
could be too long for cmd.exe, which needs not to be
called in this case. (was not cached by a test)

Introduce rules which don't use the shell and use this
rule when there are no pre or post step.

For free we get a small speedup, because cmd is then
not called.

Also be more accurate when estimating the
command line length.

1 files changed, 11 insertions, 2 deletions

diff --git a/Source/cmLocalNinjaGenerator.cxx b/Source/cmLocalNinjaGenerator.cxx
index 5d193cd..71f0913 100644
--- a/Source/cmLocalNinjaGenerator.cxx
+++ b/Source/cmLocalNinjaGenerator.cxx
@@ -264,6 +264,14 @@ void cmLocalNinjaGenerator::AppendCustomCommandDeps(const cmCustomCommand *cc,
   }
 }
 
+std::string cmLocalNinjaGenerator::nopCommand() const {
+#ifdef _WIN32
+    return "cd .";
+#else
+    return ":";
+#endif
+}
+
 std::string cmLocalNinjaGenerator::BuildCommandLine(
                                     const std::vector<std::string> &cmdLines)
 {
@@ -272,9 +280,10 @@ std::string cmLocalNinjaGenerator::BuildCommandLine(
   // don't use POST_BUILD.
   if (cmdLines.empty())
 #ifdef _WIN32
-    return "cd.";
+    return "";
 #else
-    return ":";
+    // TODO use _NOSHELL rule also on Linux
+    return nopCommand();
 #endif
 
   std::ostringstream cmd;