Merge topic 'try_compile-lang-std'

f72ba42b try_compile: Add policy CMP0067 to honor language standards
45aa03b9 try_compile: Add options to specify language standards
3bb2051e try_compile: Stop processing when test build system fails to generate

Help/command/try_compile.rst

@@ -35,7 +35,11 @@ Try Compiling Source Files
               [COMPILE_DEFINITIONS <defs>...]
               [LINK_LIBRARIES <libs>...]
               [OUTPUT_VARIABLE <var>]
-              [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]])
+              [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
+              [<LANG>_STANDARD <std>]
+              [<LANG>_STANDARD_REQUIRED <bool>]
+              [<LANG>_EXTENSIONS <bool>]
+              )
 
 Try building an executable from one or more source files.  The success or
 failure of the ``try_compile``, i.e. ``TRUE`` or ``FALSE`` respectively, is
@@ -82,6 +86,18 @@ The options are:
 ``OUTPUT_VARIABLE <var>``
   Store the output from the build process the given variable.
 
+``<LANG>_STANDARD <std>``
+  Specify the :prop_tgt:`C_STANDARD` or :prop_tgt:`CXX_STANDARD`
+  target property of the generated project.
+
+``<LANG>_STANDARD_REQUIRED <bool>``
+  Specify the :prop_tgt:`C_STANDARD_REQUIRED` or
+  :prop_tgt:`CXX_STANDARD_REQUIRED` target property of the generated project.
+
+``<LANG>_EXTENSIONS <bool>``
+  Specify the :prop_tgt:`C_EXTENSIONS` or :prop_tgt:`CXX_EXTENSIONS`
+  target property of the generated project.
+
 In this version all files in ``<bindir>/CMakeFiles/CMakeTmp`` will be
 cleaned automatically.  For debugging, ``--debug-trycompile`` can be
 passed to ``cmake`` to avoid this clean.  However, multiple sequential
@@ -119,3 +135,17 @@ the type of target used for the source file signature.
 Set the :variable:`CMAKE_TRY_COMPILE_PLATFORM_VARIABLES` variable to specify
 variables that must be propagated into the test project.  This variable is
 meant for use only in toolchain files.
+
+If :policy:`CMP0067` is set to ``NEW``, or any of the ``<LANG>_STANDARD``,
+``<LANG>_STANDARD_REQUIRED``, or ``<LANG>_EXTENSIONS`` options are used,
+then the language standard variables are honored:
+
+* :variable:`CMAKE_C_STANDARD`
+* :variable:`CMAKE_C_STANDARD_REQUIRED`
+* :variable:`CMAKE_C_EXTENSIONS`
+* :variable:`CMAKE_CXX_STANDARD`
+* :variable:`CMAKE_CXX_STANDARD_REQUIRED`
+* :variable:`CMAKE_CXX_EXTENSIONS`
+
+Their values are used to set the corresponding target properties in
+the generated project (unless overridden by an explicit option).

Help/manual/cmake-policies.7.rst

@@ -51,6 +51,14 @@ The :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` variable may also be used
 to determine whether to report an error on use of deprecated macros or
 functions.
 
+Policies Introduced by CMake 3.8
+================================
+
+.. toctree::
+   :maxdepth: 1
+
+   CMP0067: Honor language standard in try_compile() source-file signature. </policy/CMP0067>
+
 Policies Introduced by CMake 3.7
 ================================
 

Help/policy/CMP0067.rst

@@ -0,0 +1,34 @@
+CMP0067
+-------
+
+Honor language standard in :command:`try_compile` source-file signature.
+
+The :command:`try_compile` source file signature is intended to allow
+callers to check whether they will be able to compile a given source file
+with the current toolchain.  In order to match compiler behavior, any
+language standard mode should match.  However, CMake 3.7 and below did not
+do this.  CMake 3.8 and above prefer to honor the language standard settings
+for ``C`` and ``CXX`` (C++) using the values of the variables:
+
+* :variable:`CMAKE_C_STANDARD`
+* :variable:`CMAKE_C_STANDARD_REQUIRED`
+* :variable:`CMAKE_C_EXTENSIONS`
+* :variable:`CMAKE_CXX_STANDARD`
+* :variable:`CMAKE_CXX_STANDARD_REQUIRED`
+* :variable:`CMAKE_CXX_EXTENSIONS`
+
+This policy provides compatibility for projects that do not expect
+the language standard settings to be used automatically.
+
+The ``OLD`` behavior of this policy is to ignore language standard
+setting variables when generating the ``try_compile`` test project.
+The ``NEW`` behavior of this policy is to honor language standard
+setting variables.
+
+This policy was introduced in CMake version 3.8.  Unlike most policies,
+CMake version |release| does *not* warn by default when this policy
+is not set and simply uses OLD behavior.  See documentation of the
+:variable:`CMAKE_POLICY_WARNING_CMP0067 <CMAKE_POLICY_WARNING_CMP<NNNN>>`
+variable to control the warning.
+
+.. include:: DEPRECATED.txt

Help/release/dev/try_compile-lang-std.rst

@@ -0,0 +1,9 @@
+try_compile-lang-std
+--------------------
+
+* The :command:`try_compile` command source file signature gained new options
+  to specify the language standard to use in the generated test project.
+
+* The :command:`try_compile` command source file signature now honors
+  language standard variables like :variable:`CMAKE_CXX_STANDARD`.
+  See policy :policy:`CMP0067`.

Help/variable/CMAKE_POLICY_WARNING_CMPNNNN.rst

@@ -17,6 +17,8 @@ warn by default:
   policy :policy:`CMP0065`.
 * ``CMAKE_POLICY_WARNING_CMP0066`` controls the warning for
   policy :policy:`CMP0066`.
+* ``CMAKE_POLICY_WARNING_CMP0067`` controls the warning for
+  policy :policy:`CMP0067`.
 
 This variable should not be set by a project in CMake code.  Project
 developers running CMake may set this variable in their cache to

Source/cmCoreTryCompile.cxx

@@ -46,6 +46,25 @@ static std::string const kCMAKE_TRY_COMPILE_PLATFORM_VARIABLES =
   "CMAKE_TRY_COMPILE_PLATFORM_VARIABLES";
 static std::string const kCMAKE_WARN_DEPRECATED = "CMAKE_WARN_DEPRECATED";
 
+static void writeProperty(FILE* fout, std::string const& targetName,
+                          std::string const& prop, std::string const& value)
+{
+  fprintf(fout, "set_property(TARGET %s PROPERTY %s %s)\n", targetName.c_str(),
+          cmOutputConverter::EscapeForCMake(prop).c_str(),
+          cmOutputConverter::EscapeForCMake(value).c_str());
+}
+
+std::string cmCoreTryCompile::LookupStdVar(std::string const& var,
+                                           bool warnCMP0067)
+{
+  std::string value = this->Makefile->GetSafeDefinition(var);
+  if (warnCMP0067 && !value.empty()) {
+    value.clear();
+    this->WarnCMP0067.push_back(var);
+  }
+  return value;
+}
+
 int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
                                      bool isTryRun)
 {
@@ -87,6 +106,12 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
   std::string outputVariable;
   std::string copyFile;
   std::string copyFileError;
+  std::string cStandard;
+  std::string cxxStandard;
+  std::string cStandardRequired;
+  std::string cxxStandardRequired;
+  std::string cExtensions;
+  std::string cxxExtensions;
   std::vector<std::string> targets;
   std::string libsToLink = " ";
   bool useOldLinkLibs = true;
@@ -94,6 +119,12 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
   bool didOutputVariable = false;
   bool didCopyFile = false;
   bool didCopyFileError = false;
+  bool didCStandard = false;
+  bool didCxxStandard = false;
+  bool didCStandardRequired = false;
+  bool didCxxStandardRequired = false;
+  bool didCExtensions = false;
+  bool didCxxExtensions = false;
   bool useSources = argv[2] == "SOURCES";
   std::vector<std::string> sources;
 
@@ -106,6 +137,12 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     DoingOutputVariable,
     DoingCopyFile,
     DoingCopyFileError,
+    DoingCStandard,
+    DoingCxxStandard,
+    DoingCStandardRequired,
+    DoingCxxStandardRequired,
+    DoingCExtensions,
+    DoingCxxExtensions,
     DoingSources
   };
   Doing doing = useSources ? DoingSources : DoingNone;
@@ -126,6 +163,24 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     } else if (argv[i] == "COPY_FILE_ERROR") {
       doing = DoingCopyFileError;
       didCopyFileError = true;
+    } else if (argv[i] == "C_STANDARD") {
+      doing = DoingCStandard;
+      didCStandard = true;
+    } else if (argv[i] == "CXX_STANDARD") {
+      doing = DoingCxxStandard;
+      didCxxStandard = true;
+    } else if (argv[i] == "C_STANDARD_REQUIRED") {
+      doing = DoingCStandardRequired;
+      didCStandardRequired = true;
+    } else if (argv[i] == "CXX_STANDARD_REQUIRED") {
+      doing = DoingCxxStandardRequired;
+      didCxxStandardRequired = true;
+    } else if (argv[i] == "C_EXTENSIONS") {
+      doing = DoingCExtensions;
+      didCExtensions = true;
+    } else if (argv[i] == "CXX_EXTENSIONS") {
+      doing = DoingCxxExtensions;
+      didCxxExtensions = true;
     } else if (doing == DoingCMakeFlags) {
       cmakeFlags.push_back(argv[i]);
     } else if (doing == DoingCompileDefinitions) {
@@ -166,6 +221,24 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     } else if (doing == DoingCopyFileError) {
       copyFileError = argv[i];
       doing = DoingNone;
+    } else if (doing == DoingCStandard) {
+      cStandard = argv[i];
+      doing = DoingNone;
+    } else if (doing == DoingCxxStandard) {
+      cxxStandard = argv[i];
+      doing = DoingNone;
+    } else if (doing == DoingCStandardRequired) {
+      cStandardRequired = argv[i];
+      doing = DoingNone;
+    } else if (doing == DoingCxxStandardRequired) {
+      cxxStandardRequired = argv[i];
+      doing = DoingNone;
+    } else if (doing == DoingCExtensions) {
+      cExtensions = argv[i];
+      doing = DoingNone;
+    } else if (doing == DoingCxxExtensions) {
+      cxxExtensions = argv[i];
+      doing = DoingNone;
     } else if (doing == DoingSources) {
       sources.push_back(argv[i]);
     } else if (i == 3) {
@@ -213,6 +286,42 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     return -1;
   }
 
+  if (didCStandard && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR, "C_STANDARD allowed only in source file signature.");
+    return -1;
+  }
+  if (didCxxStandard && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR,
+      "CXX_STANDARD allowed only in source file signature.");
+    return -1;
+  }
+  if (didCStandardRequired && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR,
+      "C_STANDARD_REQUIRED allowed only in source file signature.");
+    return -1;
+  }
+  if (didCxxStandardRequired && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR,
+      "CXX_STANDARD_REQUIRED allowed only in source file signature.");
+    return -1;
+  }
+  if (didCExtensions && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR,
+      "C_EXTENSIONS allowed only in source file signature.");
+    return -1;
+  }
+  if (didCxxExtensions && !this->SrcFileSignature) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR,
+      "CXX_EXTENSIONS allowed only in source file signature.");
+    return -1;
+  }
+
   // compute the binary dir when TRY_COMPILE is called with a src file
   // signature
   if (this->SrcFileSignature) {
@@ -518,6 +627,104 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
       }
     }
     fprintf(fout, ")\n");
+
+    bool const testC = testLangs.find("C") != testLangs.end();
+    bool const testCxx = testLangs.find("CXX") != testLangs.end();
+
+    bool warnCMP0067 = false;
+    bool honorStandard = true;
+
+    if (!didCStandard && !didCxxStandard && !didCStandardRequired &&
+        !didCxxStandardRequired && !didCExtensions && !didCxxExtensions) {
+      switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP0067)) {
+        case cmPolicies::WARN:
+          warnCMP0067 = this->Makefile->PolicyOptionalWarningEnabled(
+            "CMAKE_POLICY_WARNING_CMP0067");
+        case cmPolicies::OLD:
+          // OLD behavior is to not honor the language standard variables.
+          honorStandard = false;
+          break;
+        case cmPolicies::REQUIRED_IF_USED:
+        case cmPolicies::REQUIRED_ALWAYS:
+          this->Makefile->IssueMessage(
+            cmake::FATAL_ERROR,
+            cmPolicies::GetRequiredPolicyError(cmPolicies::CMP0067));
+        case cmPolicies::NEW:
+          // NEW behavior is to honor the language standard variables.
+          // We already initialized honorStandard to true.
+          break;
+      }
+    }
+
+    if (honorStandard || warnCMP0067) {
+      if (testC) {
+        if (!didCStandard) {
+          cStandard = this->LookupStdVar("CMAKE_C_STANDARD", warnCMP0067);
+        }
+        if (!didCStandardRequired) {
+          cStandardRequired =
+            this->LookupStdVar("CMAKE_C_STANDARD_REQUIRED", warnCMP0067);
+        }
+        if (!didCExtensions) {
+          cExtensions = this->LookupStdVar("CMAKE_C_EXTENSIONS", warnCMP0067);
+        }
+      }
+      if (testCxx) {
+        if (!didCxxStandard) {
+          cxxStandard = this->LookupStdVar("CMAKE_CXX_STANDARD", warnCMP0067);
+        }
+        if (!didCxxStandardRequired) {
+          cxxStandardRequired =
+            this->LookupStdVar("CMAKE_CXX_STANDARD_REQUIRED", warnCMP0067);
+        }
+        if (!didCxxExtensions) {
+          cxxExtensions =
+            this->LookupStdVar("CMAKE_CXX_EXTENSIONS", warnCMP0067);
+        }
+      }
+    }
+
+    if (!this->WarnCMP0067.empty()) {
+      std::ostringstream w;
+      /* clang-format off */
+      w << cmPolicies::GetPolicyWarning(cmPolicies::CMP0067) << "\n"
+        "For compatibility with older versions of CMake, try_compile "
+        "is not honoring language standard variables in the test project:\n"
+        ;
+      /* clang-format on */
+      for (std::vector<std::string>::iterator vi = this->WarnCMP0067.begin();
+           vi != this->WarnCMP0067.end(); ++vi) {
+        w << "  " << *vi << "\n";
+      }
+      this->Makefile->IssueMessage(cmake::AUTHOR_WARNING, w.str());
+    }
+
+    if (testC) {
+      if (!cStandard.empty()) {
+        writeProperty(fout, targetName, "C_STANDARD", cStandard);
+      }
+      if (!cStandardRequired.empty()) {
+        writeProperty(fout, targetName, "C_STANDARD_REQUIRED",
+                      cStandardRequired);
+      }
+      if (!cExtensions.empty()) {
+        writeProperty(fout, targetName, "C_EXTENSIONS", cExtensions);
+      }
+    }
+
+    if (testCxx) {
+      if (!cxxStandard.empty()) {
+        writeProperty(fout, targetName, "CXX_STANDARD", cxxStandard);
+      }
+      if (!cxxStandardRequired.empty()) {
+        writeProperty(fout, targetName, "CXX_STANDARD_REQUIRED",
+                      cxxStandardRequired);
+      }
+      if (!cxxExtensions.empty()) {
+        writeProperty(fout, targetName, "CXX_EXTENSIONS", cxxExtensions);
+      }
+    }
+
     if (useOldLinkLibs) {
       fprintf(fout, "target_link_libraries(%s ${LINK_LIBRARIES})\n",
               targetName.c_str());

Source/cmCoreTryCompile.h

@@ -47,6 +47,10 @@ protected:
   std::string OutputFile;
   std::string FindErrorMessage;
   bool SrcFileSignature;
+
+private:
+  std::vector<std::string> WarnCMP0067;
+  std::string LookupStdVar(std::string const& var, bool warnCMP0067);
 };
 
 #endif

Source/cmMakefile.cxx

@@ -3158,8 +3158,10 @@ int cmMakefile::TryCompile(const std::string& srcdir,
   cmGlobalGenerator* gg =
     cm.CreateGlobalGenerator(this->GetGlobalGenerator()->GetName());
   if (!gg) {
-    cmSystemTools::Error(
-      "Internal CMake error, TryCompile bad GlobalGenerator");
+    this->IssueMessage(cmake::INTERNAL_ERROR, "Global generator '" +
+                         this->GetGlobalGenerator()->GetName() +
+                         "' could not be created.");
+    cmSystemTools::SetFatalErrorOccured();
     // return to the original directory
     cmSystemTools::ChangeDirectory(cwd);
     this->IsSourceFileTryCompile = false;
@@ -3222,8 +3224,9 @@ int cmMakefile::TryCompile(const std::string& srcdir,
                      cmStateEnums::INTERNAL);
   }
   if (cm.Configure() != 0) {
-    cmSystemTools::Error(
-      "Internal CMake error, TryCompile configure of cmake failed");
+    this->IssueMessage(cmake::FATAL_ERROR,
+                       "Failed to configure test project build system.");
+    cmSystemTools::SetFatalErrorOccured();
     // return to the original directory
     cmSystemTools::ChangeDirectory(cwd);
     this->IsSourceFileTryCompile = false;
@@ -3231,8 +3234,9 @@ int cmMakefile::TryCompile(const std::string& srcdir,
   }
 
   if (cm.Generate() != 0) {
-    cmSystemTools::Error(
-      "Internal CMake error, TryCompile generation of cmake failed");
+    this->IssueMessage(cmake::FATAL_ERROR,
+                       "Failed to generate test project build system.");
+    cmSystemTools::SetFatalErrorOccured();
     // return to the original directory
     cmSystemTools::ChangeDirectory(cwd);
     this->IsSourceFileTryCompile = false;

Source/cmPolicies.h

@@ -197,7 +197,10 @@ class cmMakefile;
          3, 4, 0, cmPolicies::WARN)                                           \
   SELECT(POLICY, CMP0066,                                                     \
          "Honor per-config flags in try_compile() source-file signature.", 3, \
-         7, 0, cmPolicies::WARN)
+         7, 0, cmPolicies::WARN)                                              \
+  SELECT(POLICY, CMP0067,                                                     \
+         "Honor language standard in try_compile() source-file signature.",   \
+         3, 8, 0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \

Tests/RunCMake/CMakeLists.txt

@@ -215,6 +215,18 @@ add_RunCMake_test(project -DCMake_TEST_RESOURCES=${CMake_TEST_RESOURCES})
 add_RunCMake_test(return)
 add_RunCMake_test(set_property)
 add_RunCMake_test(string)
+foreach(var
+    CMAKE_C_COMPILER_ID
+    CMAKE_C_COMPILER_VERSION
+    CMAKE_C_STANDARD_DEFAULT
+    CMAKE_CXX_COMPILER_ID
+    CMAKE_CXX_COMPILER_VERSION
+    CMAKE_CXX_STANDARD_DEFAULT
+    )
+  if(DEFINED ${var})
+    list(APPEND try_compile_ARGS -D${var}=${${var}})
+  endif()
+endforeach()
 add_RunCMake_test(try_compile)
 add_RunCMake_test(try_run)
 add_RunCMake_test(set)

Tests/RunCMake/try_compile/CMP0067-stderr.txt

@@ -0,0 +1,25 @@
+before try_compile with CMP0067 WARN-enabled but no variables
+after try_compile with CMP0067 WARN-enabled but no variables
+before try_compile with CMP0067 WARN-default
+after try_compile with CMP0067 WARN-default
+before try_compile with CMP0067 WARN-enabled
+CMake Warning \(dev\) at CMP0067.cmake:[0-9]+ \(try_compile\):
+  Policy CMP0067 is not set: Honor language standard in try_compile\(\)
+  source-file signature.  Run "cmake --help-policy CMP0067" for policy
+  details.  Use the cmake_policy command to set the policy and suppress this
+  warning.
+
+  For compatibility with older versions of CMake, try_compile is not honoring
+  language standard variables in the test project:
+
+    CMAKE_C_STANDARD
+
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+after try_compile with CMP0067 WARN-enabled
+before try_compile with CMP0067 OLD
+after try_compile with CMP0067 OLD
+before try_compile with CMP0067 NEW
+after try_compile with CMP0067 NEW

Tests/RunCMake/try_compile/CMP0067.cmake

@@ -0,0 +1,40 @@
+enable_language(C)
+
+set(CMAKE_POLICY_WARNING_CMP0067 ON)
+message("before try_compile with CMP0067 WARN-enabled but no variables")
+try_compile(RESULT ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  )
+message("after try_compile with CMP0067 WARN-enabled but no variables")
+set(CMAKE_POLICY_WARNING_CMP0067 OFF)
+
+#-----------------------------------------------------------------------------
+
+set(CMAKE_C_STANDARD 90)
+
+message("before try_compile with CMP0067 WARN-default")
+try_compile(RESULT ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  )
+message("after try_compile with CMP0067 WARN-default")
+
+set(CMAKE_POLICY_WARNING_CMP0067 ON)
+message("before try_compile with CMP0067 WARN-enabled")
+try_compile(RESULT ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  )
+message("after try_compile with CMP0067 WARN-enabled")
+
+cmake_policy(SET CMP0067 OLD)
+message("before try_compile with CMP0067 OLD")
+try_compile(RESULT ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  )
+message("after try_compile with CMP0067 OLD")
+
+cmake_policy(SET CMP0066 NEW)
+message("before try_compile with CMP0067 NEW")
+try_compile(RESULT ${CMAKE_CURRENT_BINARY_DIR}
+  ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  )
+message("after try_compile with CMP0067 NEW")

Tests/RunCMake/try_compile/CStandard-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/try_compile/CStandard-stderr.txt

@@ -0,0 +1,7 @@
+^CMake Error at .*/Tests/RunCMake/try_compile/CStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
+  C_STANDARD is set to invalid value '3'
++
+CMake Error at CStandard.cmake:[0-9]+ \(try_compile\):
+  Failed to generate test project build system.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/try_compile/CStandard.cmake

@@ -0,0 +1,7 @@
+enable_language(C)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  C_STANDARD 3
+  OUTPUT_VARIABLE out
+  )
+message("try_compile output:\n${out}")

Tests/RunCMake/try_compile/CStandardGNU.c

@@ -0,0 +1,10 @@
+#if __STDC_VERSION__ != 199901L
+#error "Not GNU C 99 mode!"
+#endif
+#ifndef __STRICT_ANSI__
+#error "Not GNU C strict ANSI!"
+#endif
+int main(void)
+{
+  return 0;
+}

Tests/RunCMake/try_compile/CStandardGNU.cmake

@@ -0,0 +1,23 @@
+enable_language(C)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/CStandardGNU.c
+  C_STANDARD 99
+  C_STANDARD_REQUIRED 1
+  C_EXTENSIONS 0
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()
+
+cmake_policy(SET CMP0067 NEW)
+set(CMAKE_C_STANDARD 99)
+set(CMAKE_C_STANDARD_REQUIRED 1)
+set(CMAKE_C_EXTENSIONS 0)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/CStandardGNU.c
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()

Tests/RunCMake/try_compile/CStandardNoDefault.cmake

@@ -0,0 +1,9 @@
+enable_language(C)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.c
+  C_STANDARD 3 # bogus, but not used
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()

Tests/RunCMake/try_compile/CxxStandard-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/try_compile/CxxStandard-stderr.txt

@@ -0,0 +1,7 @@
+^CMake Error at .*/Tests/RunCMake/try_compile/CxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
+  CXX_STANDARD is set to invalid value '3'
++
+CMake Error at CxxStandard.cmake:[0-9]+ \(try_compile\):
+  Failed to generate test project build system.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/try_compile/CxxStandard.cmake

@@ -0,0 +1,7 @@
+enable_language(CXX)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.cxx
+  CXX_STANDARD 3
+  OUTPUT_VARIABLE out
+  )
+message("try_compile output:\n${out}")

Tests/RunCMake/try_compile/CxxStandardGNU.cmake

@@ -0,0 +1,23 @@
+enable_language(CXX)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/CxxStandardGNU.cxx
+  CXX_STANDARD 11
+  CXX_STANDARD_REQUIRED 1
+  CXX_EXTENSIONS 0
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()
+
+cmake_policy(SET CMP0067 NEW)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED 1)
+set(CMAKE_CXX_EXTENSIONS 0)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/CxxStandardGNU.cxx
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()

Tests/RunCMake/try_compile/CxxStandardGNU.cxx

@@ -0,0 +1,11 @@
+#if __cplusplus != 201103L &&                                                 \
+  !(__cplusplus < 201103L && defined(__GXX_EXPERIMENTAL_CXX0X__))
+#error "Not GNU C++ 11 mode!"
+#endif
+#ifndef __STRICT_ANSI__
+#error "Not GNU C++ strict ANSI!"
+#endif
+int main()
+{
+  return 0;
+}

Tests/RunCMake/try_compile/CxxStandardNoDefault.cmake

@@ -0,0 +1,9 @@
+enable_language(CXX)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.cxx
+  CXX_STANDARD 3 # bogus, but not used
+  OUTPUT_VARIABLE out
+  )
+if(NOT result)
+  message(FATAL_ERROR "try_compile failed:\n${out}")
+endif()

Tests/RunCMake/try_compile/RunCMakeTest.cmake

@@ -25,8 +25,26 @@ run_cmake(TargetTypeExe)
 run_cmake(TargetTypeInvalid)
 run_cmake(TargetTypeStatic)
 
+if(CMAKE_C_STANDARD_DEFAULT)
+  run_cmake(CStandard)
+elseif(DEFINED CMAKE_C_STANDARD_DEFAULT)
+  run_cmake(CStandardNoDefault)
+endif()
+if(CMAKE_CXX_STANDARD_DEFAULT)
+  run_cmake(CxxStandard)
+elseif(DEFINED CMAKE_CXX_STANDARD_DEFAULT)
+  run_cmake(CxxStandardNoDefault)
+endif()
+if(CMAKE_C_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
+  run_cmake(CStandardGNU)
+endif()
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.4)
+  run_cmake(CxxStandardGNU)
+endif()
+
 run_cmake(CMP0056)
 run_cmake(CMP0066)
+run_cmake(CMP0067)
 
 if(RunCMake_GENERATOR MATCHES "Make|Ninja")
   # Use a single build tree for a few tests without cleaning.

Tests/RunCMake/try_compile/src.cxx

@@ -0,0 +1,4 @@
+int main()
+{
+  return 0;
+}