try_run: Use CMAKE_CROSSCOMPILING_EMULATOR.

If the CMAKE_CROSSCOMPILING_EMULATOR variable is defined, and
CMAKE_CROSSCOMPILING is TRUE, then use CMAKE_CROSSCOMPILING_EMULATOR to run
the try_run executables. This prevents the need to populate
TryRunResults.cmake when cross compiling.

7 files changed, 56 insertions, 6 deletions

diff --git a/Help/command/try_run.rst b/Help/command/try_run.rst
index 43ee21960e..e3bd57d501 100644
--- a/Help/command/try_run.rst
+++ b/Help/command/try_run.rst
@@ -73,7 +73,8 @@ When cross compiling, the executable compiled in the first step
 usually cannot be run on the build host.  The ``try_run`` command checks
 the :variable:`CMAKE_CROSSCOMPILING` variable to detect whether CMake is in
 cross-compiling mode.  If that is the case, it will still try to compile
-the executable, but it will not try to run the executable.  Instead it
+the executable, but it will not try to run the executable unless the
+:variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable is set.  Instead it
 will create cache variables which must be filled by the user or by
 presetting them in some CMake script file to the values the executable
 would have produced if it had been run on its actual target platform.
diff --git a/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst b/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
index fa6f1b743d..95d2c7ffc4 100644
--- a/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
+++ b/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
@@ -1,5 +1,12 @@
 CMAKE_CROSSCOMPILING_EMULATOR
 -----------------------------
 
-Default value for the :prop_tgt:`CROSSCOMPILING_EMULATOR` target property of
-executables.  See that target property for additional information.
+This variable is only used when :variable:`CMAKE_CROSSCOMPILING` is on. It
+should point to a command on the host system that can run executable built
+for the target system.
+
+The command will be used to run :command:`try_run` generated executables,
+which avoids manual population of the TryRunResults.cmake file.
+
+It is also used as the default value for the
+:prop_tgt:`CROSSCOMPILING_EMULATOR` target property of executables.
diff --git a/Source/cmTryRunCommand.cxx b/Source/cmTryRunCommand.cxx
index b5280cfd75..8b68d64c16 100644
--- a/Source/cmTryRunCommand.cxx
+++ b/Source/cmTryRunCommand.cxx
@@ -149,7 +149,8 @@ bool cmTryRunCommand
       {
       // "run" it and capture the output
       std::string runOutputContents;
-      if (this->Makefile->IsOn("CMAKE_CROSSCOMPILING"))
+      if (this->Makefile->IsOn("CMAKE_CROSSCOMPILING") &&
+          !this->Makefile->IsDefinitionSet("CMAKE_CROSSCOMPILING_EMULATOR"))
         {
         this->DoNotRunExecutable(runArgs,
                                  argv[3],
@@ -195,7 +196,28 @@ void cmTryRunCommand::RunExecutable(const std::string& runArgs,
                                     std::string* out)
 {
   int retVal = -1;
-  std::string finalCommand = cmSystemTools::ConvertToRunCommandPath(
+
+  std::string finalCommand;
+  const std::string emulator =
+  this->Makefile->GetSafeDefinition("CMAKE_CROSSCOMPILING_EMULATOR");
+  if (!emulator.empty())
+    {
+    std::vector<std::string> emulatorWithArgs;
+    cmSystemTools::ExpandListArgument(emulator, emulatorWithArgs);
+    finalCommand += cmSystemTools::ConvertToRunCommandPath(
+                                 emulatorWithArgs[0].c_str());
+    finalCommand += " ";
+    for (std::vector<std::string>::const_iterator ei =
+         emulatorWithArgs.begin()+1;
+         ei != emulatorWithArgs.end(); ++ei)
+      {
+      finalCommand += "\"";
+      finalCommand += *ei;
+      finalCommand += "\"";
+      finalCommand += " ";
+      }
+    }
+  finalCommand += cmSystemTools::ConvertToRunCommandPath(
                                this->OutputFile.c_str());
   if (!runArgs.empty())
     {
diff --git a/Tests/RunCMake/CrosscompilingEmulator/RunCMakeTest.cmake b/Tests/RunCMake/CrosscompilingEmulator/RunCMakeTest.cmake
index cecc57f860..04fb7db84f 100644
--- a/Tests/RunCMake/CrosscompilingEmulator/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CrosscompilingEmulator/RunCMakeTest.cmake
@@ -4,3 +4,4 @@ set(RunCMake_TEST_OPTIONS
     "-DCMAKE_CROSSCOMPILING_EMULATOR=${PSEUDO_EMULATOR}")
 
 run_cmake(CrosscompilingEmulatorProperty)
+run_cmake(TryRun)
diff --git a/Tests/RunCMake/CrosscompilingEmulator/TryRun-stdout.txt b/Tests/RunCMake/CrosscompilingEmulator/TryRun-stdout.txt
new file mode 100644
index 0000000000..d012974b52
--- /dev/null
+++ b/Tests/RunCMake/CrosscompilingEmulator/TryRun-stdout.txt
@@ -0,0 +1 @@
+run_result: 42
diff --git a/Tests/RunCMake/CrosscompilingEmulator/TryRun.cmake b/Tests/RunCMake/CrosscompilingEmulator/TryRun.cmake
new file mode 100644
index 0000000000..4851cc7781
--- /dev/null
+++ b/Tests/RunCMake/CrosscompilingEmulator/TryRun.cmake
@@ -0,0 +1,18 @@
+set(CMAKE_CROSSCOMPILING 1)
+
+try_run(run_result compile_result
+  ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/simple_src.cxx
+  RUN_OUTPUT_VARIABLE run_output)
+
+message(STATUS "run_output: ${run_output}")
+message(STATUS "run_result: ${run_result}")
+
+set(CMAKE_CROSSCOMPILING_EMULATOR ${CMAKE_CROSSCOMPILING_EMULATOR}
+  --flag
+  "multi arg")
+try_run(run_result compile_result
+  ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/simple_src.cxx
+  RUN_OUTPUT_VARIABLE run_output)
+message(STATUS "Emulator with arguments run_output: ${run_output}")
diff --git a/Tests/RunCMake/CrosscompilingEmulator/simple_src.cxx b/Tests/RunCMake/CrosscompilingEmulator/simple_src.cxx
index 630adc6bc2..e5e94f27ec 100644
--- a/Tests/RunCMake/CrosscompilingEmulator/simple_src.cxx
+++ b/Tests/RunCMake/CrosscompilingEmulator/simple_src.cxx
@@ -1,4 +1,4 @@
 int main(int, char **)
 {
-  return 0;
+  return 13;
 }