try_compile: Refactor language standard level parsing

cmCoreTryCompile had significant code duplication around handling
languages that offer standard levels. This refactoring reduces
the complexity and makes it easier to add new languages in the
future.

Source/cmCoreTryCompile.cxx

@@ -25,6 +25,148 @@
 #include "cmVersion.h"
 #include "cmake.h"
 
+namespace {
+class LanguageStandardState
+{
+public:
+  LanguageStandardState(std::string&& lang)
+    : IsEnabled(false)
+    , DidStandard(false)
+    , DidStandardRequired(false)
+    , DidExtensions(false)
+    , StandardFlag(lang + "_STANDARD")
+    , RequiredFlag(lang + "_STANDARD_REQUIRED")
+    , ExtensionFlag(lang + "_EXTENSIONS")
+  {
+  }
+
+  void Enabled(bool isEnabled) { this->IsEnabled = isEnabled; }
+
+  bool UpdateIfMatches(std::vector<std::string> const& argv, size_t& index)
+  {
+    bool updated = false;
+    if (argv[index] == this->StandardFlag) {
+      this->DidStandard = true;
+      this->StandardValue = argv[++index];
+      updated = true;
+    } else if (argv[index] == this->RequiredFlag) {
+      this->DidStandardRequired = true;
+      this->RequiredValue = argv[++index];
+      updated = true;
+    } else if (argv[index] == this->ExtensionFlag) {
+      this->DidExtensions = true;
+      this->ExtensionValue = argv[++index];
+      updated = true;
+    }
+    return updated;
+  }
+
+  bool Validate(cmMakefile* const makefile) const
+  {
+    if (this->DidStandard) {
+      makefile->IssueMessage(
+        MessageType::FATAL_ERROR,
+        cmStrCat(this->StandardFlag,
+                 " allowed only in source file signature."));
+      return false;
+    }
+    if (this->DidStandardRequired) {
+      makefile->IssueMessage(
+        MessageType::FATAL_ERROR,
+        cmStrCat(this->RequiredFlag,
+                 " allowed only in source file signature."));
+      return false;
+    }
+    if (this->DidExtensions) {
+      makefile->IssueMessage(
+        MessageType::FATAL_ERROR,
+        cmStrCat(this->ExtensionFlag,
+                 " allowed only in source file signature."));
+      return false;
+    }
+
+    return true;
+  }
+
+  bool DidNone() const
+  {
+    return !this->DidStandard && !this->DidStandardRequired &&
+      !this->DidExtensions;
+  }
+
+  void LoadUnsetPropertyValues(cmMakefile* const makefile, bool honorStandard,
+                               bool warnCMP0067,
+                               std::vector<std::string>& warnCMP0067Variables)
+  {
+    if (!this->IsEnabled) {
+      return;
+    }
+
+    auto lookupStdVar = [&](std::string const& var) -> std::string {
+      std::string value = makefile->GetSafeDefinition(var);
+      if (warnCMP0067 && !value.empty()) {
+        value.clear();
+        warnCMP0067Variables.push_back(var);
+      }
+      return value;
+    };
+
+    if (honorStandard || warnCMP0067) {
+      if (!this->DidStandard) {
+        this->StandardValue =
+          lookupStdVar(cmStrCat("CMAKE_", this->StandardFlag));
+      }
+      if (!this->DidStandardRequired) {
+        this->RequiredValue =
+          lookupStdVar(cmStrCat("CMAKE_", this->RequiredFlag));
+      }
+      if (!this->DidExtensions) {
+        this->ExtensionValue =
+          lookupStdVar(cmStrCat("CMAKE_", this->ExtensionFlag));
+      }
+    }
+  }
+
+  void WriteProperties(FILE* fout, std::string const& targetName) const
+  {
+    if (!this->IsEnabled) {
+      return;
+    }
+
+    auto writeProp = [&](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());
+    };
+
+    if (!this->StandardValue.empty()) {
+      writeProp(this->StandardFlag, this->StandardValue);
+    }
+    if (!this->RequiredValue.empty()) {
+      writeProp(this->RequiredFlag, this->RequiredValue);
+    }
+    if (!this->ExtensionValue.empty()) {
+      writeProp(this->ExtensionFlag, this->ExtensionValue);
+    }
+  }
+
+private:
+  bool IsEnabled;
+  bool DidStandard;
+  bool DidStandardRequired;
+  bool DidExtensions;
+
+  std::string StandardFlag;
+  std::string RequiredFlag;
+  std::string ExtensionFlag;
+
+  std::string StandardValue;
+  std::string RequiredValue;
+  std::string ExtensionValue;
+};
+}
+
 static std::string const kCMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN =
   "CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN";
 static std::string const kCMAKE_C_COMPILER_TARGET = "CMAKE_C_COMPILER_TARGET";
@@ -79,25 +221,6 @@ static std::set<std::string> ghs_platform_vars{
   "GHS_OS_DIR_OPTION"
 };
 
-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)
 {
@@ -137,21 +260,11 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
   std::string outputVariable;
   std::string copyFile;
   std::string copyFileError;
-  std::string cStandard;
-  std::string objcStandard;
-  std::string cxxStandard;
-  std::string objcxxStandard;
-  std::string cudaStandard;
-  std::string cStandardRequired;
-  std::string cxxStandardRequired;
-  std::string objcStandardRequired;
-  std::string objcxxStandardRequired;
-  std::string cudaStandardRequired;
-  std::string cExtensions;
-  std::string cxxExtensions;
-  std::string objcExtensions;
-  std::string objcxxExtensions;
-  std::string cudaExtensions;
+  LanguageStandardState cState("C");
+  LanguageStandardState cudaState("CUDA");
+  LanguageStandardState cxxState("CXX");
+  LanguageStandardState objcState("OBJC");
+  LanguageStandardState objcxxState("OBJCXX");
   std::vector<std::string> targets;
   std::vector<std::string> linkOptions;
   std::string libsToLink = " ";
@@ -160,21 +273,6 @@ 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 didObjCStandard = false;
-  bool didObjCxxStandard = false;
-  bool didCudaStandard = false;
-  bool didCStandardRequired = false;
-  bool didCxxStandardRequired = false;
-  bool didObjCStandardRequired = false;
-  bool didObjCxxStandardRequired = false;
-  bool didCudaStandardRequired = false;
-  bool didCExtensions = false;
-  bool didCxxExtensions = false;
-  bool didObjCExtensions = false;
-  bool didObjCxxExtensions = false;
-  bool didCudaExtensions = false;
   bool useSources = argv[2] == "SOURCES";
   std::vector<std::string> sources;
 
@@ -188,21 +286,6 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     DoingOutputVariable,
     DoingCopyFile,
     DoingCopyFileError,
-    DoingCStandard,
-    DoingCxxStandard,
-    DoingObjCStandard,
-    DoingObjCxxStandard,
-    DoingCudaStandard,
-    DoingCStandardRequired,
-    DoingCxxStandardRequired,
-    DoingObjCStandardRequired,
-    DoingObjCxxStandardRequired,
-    DoingCudaStandardRequired,
-    DoingCExtensions,
-    DoingCxxExtensions,
-    DoingObjCExtensions,
-    DoingObjCxxExtensions,
-    DoingCudaExtensions,
     DoingSources,
     DoingCMakeInternal
   };
@@ -226,51 +309,12 @@ 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] == "OBJC_STANDARD") {
-      doing = DoingObjCStandard;
-      didObjCStandard = true;
-    } else if (argv[i] == "OBJCXX_STANDARD") {
-      doing = DoingObjCxxStandard;
-      didObjCxxStandard = true;
-    } else if (argv[i] == "CUDA_STANDARD") {
-      doing = DoingCudaStandard;
-      didCudaStandard = 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] == "OBJC_STANDARD_REQUIRED") {
-      doing = DoingObjCStandardRequired;
-      didObjCStandardRequired = true;
-    } else if (argv[i] == "OBJCXX_STANDARD_REQUIRED") {
-      doing = DoingObjCxxStandardRequired;
-      didObjCxxStandardRequired = true;
-    } else if (argv[i] == "CUDA_STANDARD_REQUIRED") {
-      doing = DoingCudaStandardRequired;
-      didCudaStandardRequired = true;
-    } else if (argv[i] == "C_EXTENSIONS") {
-      doing = DoingCExtensions;
-      didCExtensions = true;
-    } else if (argv[i] == "CXX_EXTENSIONS") {
-      doing = DoingCxxExtensions;
-      didCxxExtensions = true;
-    } else if (argv[i] == "OBJC_EXTENSIONS") {
-      doing = DoingObjCExtensions;
-      didObjCExtensions = true;
-    } else if (argv[i] == "OBJCXX_EXTENSIONS") {
-      doing = DoingObjCxxExtensions;
-      didObjCxxExtensions = true;
-    } else if (argv[i] == "CUDA_EXTENSIONS") {
-      doing = DoingCudaExtensions;
-      didCudaExtensions = true;
+    } else if (cState.UpdateIfMatches(argv, i) ||
+               cxxState.UpdateIfMatches(argv, i) ||
+               cudaState.UpdateIfMatches(argv, i) ||
+               objcState.UpdateIfMatches(argv, i) ||
+               objcxxState.UpdateIfMatches(argv, i)) {
+      continue;
     } else if (argv[i] == "__CMAKE_INTERNAL") {
       doing = DoingCMakeInternal;
     } else if (doing == DoingCMakeFlags) {
@@ -315,51 +359,6 @@ 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 == DoingObjCStandard) {
-      objcStandard = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingObjCxxStandard) {
-      objcxxStandard = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingCudaStandard) {
-      cudaStandard = 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 == DoingObjCStandardRequired) {
-      objcStandardRequired = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingObjCxxStandardRequired) {
-      objcxxStandardRequired = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingCudaStandardRequired) {
-      cudaStandardRequired = 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 == DoingObjCExtensions) {
-      objcExtensions = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingObjCxxExtensions) {
-      objcxxExtensions = argv[i];
-      doing = DoingNone;
-    } else if (doing == DoingCudaExtensions) {
-      cudaExtensions = argv[i];
-      doing = DoingNone;
     } else if (doing == DoingSources) {
       sources.push_back(argv[i]);
     } else if (doing == DoingCMakeInternal) {
@@ -411,59 +410,22 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     return -1;
   }
 
-  if (didCStandard && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "C_STANDARD allowed only in source file signature.");
-    return -1;
-  }
-  if (didCxxStandard && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CXX_STANDARD allowed only in source file signature.");
-    return -1;
-  }
-  if (didCudaStandard && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CUDA_STANDARD allowed only in source file signature.");
-    return -1;
-  }
-  if (didCStandardRequired && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "C_STANDARD_REQUIRED allowed only in source file signature.");
-    return -1;
-  }
-  if (didCxxStandardRequired && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CXX_STANDARD_REQUIRED allowed only in source file signature.");
-    return -1;
-  }
-  if (didCudaStandardRequired && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CUDA_STANDARD_REQUIRED allowed only in source file signature.");
-    return -1;
-  }
-  if (didCExtensions && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "C_EXTENSIONS allowed only in source file signature.");
-    return -1;
-  }
-  if (didCxxExtensions && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CXX_EXTENSIONS allowed only in source file signature.");
-    return -1;
-  }
-  if (didCudaExtensions && !this->SrcFileSignature) {
-    this->Makefile->IssueMessage(
-      MessageType::FATAL_ERROR,
-      "CUDA_EXTENSIONS allowed only in source file signature.");
-    return -1;
+  if (!this->SrcFileSignature) {
+    if (!cState.Validate(this->Makefile)) {
+      return -1;
+    }
+    if (!cudaState.Validate(this->Makefile)) {
+      return -1;
+    }
+    if (!cxxState.Validate(this->Makefile)) {
+      return -1;
+    }
+    if (!objcState.Validate(this->Makefile)) {
+      return -1;
+    }
+    if (!objcxxState.Validate(this->Makefile)) {
+      return -1;
+    }
   }
 
   // compute the binary dir when TRY_COMPILE is called with a src file
@@ -819,21 +781,17 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
     }
     fprintf(fout, ")\n");
 
-    bool const testC = testLangs.find("C") != testLangs.end();
-    bool const testObjC = testLangs.find("OBJC") != testLangs.end();
-    bool const testCxx = testLangs.find("CXX") != testLangs.end();
-    bool const testObjCxx = testLangs.find("OBJCXX") != testLangs.end();
-    bool const testCuda = testLangs.find("CUDA") != testLangs.end();
+    cState.Enabled(testLangs.find("C") != testLangs.end());
+    cxxState.Enabled(testLangs.find("CXX") != testLangs.end());
+    cudaState.Enabled(testLangs.find("CUDA") != testLangs.end());
+    objcState.Enabled(testLangs.find("OBJC") != testLangs.end());
+    objcxxState.Enabled(testLangs.find("OBJCXX") != testLangs.end());
 
     bool warnCMP0067 = false;
     bool honorStandard = true;
 
-    if (!didCStandard && !didCxxStandard && !didObjCStandard &&
-        !didObjCxxStandard && !didCudaStandard && !didCStandardRequired &&
-        !didCxxStandardRequired && !didObjCStandardRequired &&
-        !didObjCxxStandardRequired && !didCudaStandardRequired &&
-        !didCExtensions && !didCxxExtensions && !didObjCExtensions &&
-        !didObjCxxExtensions && !didCudaExtensions) {
+    if (cState.DidNone() && cxxState.DidNone() && objcState.DidNone() &&
+        objcxxState.DidNone() && cudaState.DidNone()) {
       switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP0067)) {
         case cmPolicies::WARN:
           warnCMP0067 = this->Makefile->PolicyOptionalWarningEnabled(
@@ -855,46 +813,20 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
       }
     }
 
-    if (honorStandard || warnCMP0067) {
+    std::vector<std::string> warnCMP0067Variables;
 
-      auto testLanguage =
-        [&](bool testLang, bool didLangStandard, bool didLangStandardRequired,
-            bool didLangExtensions, std::string& langStandard,
-            std::string& langStandardRequired, std::string& langExtensions,
-            const std::string& lang) {
-          if (testLang) {
-            if (!didLangStandard) {
-              langStandard = this->LookupStdVar(
-                cmStrCat("CMAKE_", lang, "_STANDARD"), warnCMP0067);
-            }
-            if (!didLangStandardRequired) {
-              langStandardRequired = this->LookupStdVar(
-                cmStrCat("CMAKE_", lang, "_STANDARD_REQUIRED"), warnCMP0067);
-            }
-            if (!didLangExtensions) {
-              langExtensions = this->LookupStdVar(
-                cmStrCat("CMAKE_", lang, "_EXTENSIONS"), warnCMP0067);
-            }
-          }
-        };
-
-      testLanguage(testC, didCStandard, didCStandardRequired, didCExtensions,
-                   cStandard, cStandardRequired, cExtensions, "C");
-      testLanguage(testObjC, didObjCStandard, didObjCStandardRequired,
-                   didObjCExtensions, objcStandard, objcStandardRequired,
-                   objcExtensions, "OBJC");
-      testLanguage(testCxx, didCxxStandard, didCxxStandardRequired,
-                   didCxxExtensions, cxxStandard, cxxStandardRequired,
-                   cxxExtensions, "CXX");
-      testLanguage(testObjCxx, didObjCxxStandard, didObjCxxStandardRequired,
-                   didObjCxxExtensions, objcxxStandard, objcxxStandardRequired,
-                   objcxxExtensions, "OBJCXX");
-      testLanguage(testCuda, didCudaStandard, didCudaStandardRequired,
-                   didCudaExtensions, cudaStandard, cudaStandardRequired,
-                   cudaExtensions, "CUDA");
-    }
+    cState.LoadUnsetPropertyValues(this->Makefile, honorStandard, warnCMP0067,
+                                   warnCMP0067Variables);
+    cxxState.LoadUnsetPropertyValues(this->Makefile, honorStandard,
+                                     warnCMP0067, warnCMP0067Variables);
+    cudaState.LoadUnsetPropertyValues(this->Makefile, honorStandard,
+                                      warnCMP0067, warnCMP0067Variables);
+    objcState.LoadUnsetPropertyValues(this->Makefile, honorStandard,
+                                      warnCMP0067, warnCMP0067Variables);
+    objcxxState.LoadUnsetPropertyValues(this->Makefile, honorStandard,
+                                        warnCMP0067, warnCMP0067Variables);
 
-    if (!this->WarnCMP0067.empty()) {
+    if (!warnCMP0067Variables.empty()) {
       std::ostringstream w;
       /* clang-format off */
       w << cmPolicies::GetPolicyWarning(cmPolicies::CMP0067) << "\n"
@@ -902,43 +834,17 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
         "is not honoring language standard variables in the test project:\n"
         ;
       /* clang-format on */
-      for (std::string const& vi : this->WarnCMP0067) {
+      for (std::string const& vi : warnCMP0067Variables) {
         w << "  " << vi << "\n";
       }
       this->Makefile->IssueMessage(MessageType::AUTHOR_WARNING, w.str());
     }
 
-    auto writeLanguageProperties = [&](bool testLang,
-                                       const std::string& langStandard,
-                                       const std::string& langStandardRequired,
-                                       const std::string& langExtensions,
-                                       const std::string& lang) {
-      if (testLang) {
-        if (!langStandard.empty()) {
-          writeProperty(fout, targetName, cmStrCat(lang, "_STANDARD"),
-                        langStandard);
-        }
-        if (!langStandardRequired.empty()) {
-          writeProperty(fout, targetName, cmStrCat(lang, "_STANDARD_REQUIRED"),
-                        langStandardRequired);
-        }
-        if (!langExtensions.empty()) {
-          writeProperty(fout, targetName, cmStrCat(lang, "_EXTENSIONS"),
-                        langExtensions);
-        }
-      }
-    };
-
-    writeLanguageProperties(testC, cStandard, cStandardRequired, cExtensions,
-                            "C");
-    writeLanguageProperties(testObjC, objcStandard, objcStandardRequired,
-                            objcExtensions, "OBJC");
-    writeLanguageProperties(testCxx, cxxStandard, cxxStandardRequired,
-                            cxxExtensions, "CXX");
-    writeLanguageProperties(testObjCxx, objcxxStandard, objcxxStandardRequired,
-                            objcxxExtensions, "OBJCXX");
-    writeLanguageProperties(testCuda, cudaStandard, cudaStandardRequired,
-                            cudaExtensions, "CUDA");
+    cState.WriteProperties(fout, targetName);
+    cxxState.WriteProperties(fout, targetName);
+    cudaState.WriteProperties(fout, targetName);
+    objcState.WriteProperties(fout, targetName);
+    objcxxState.WriteProperties(fout, targetName);
 
     if (!linkOptions.empty()) {
       std::vector<std::string> options;

Source/cmCoreTryCompile.h

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