CSharp: Fix regression in VS project type selection for custom target

A target created by `add_custom_target` should always be a `.vcxproj`
file even if it has `.cs` sources involved in custom commands and such.
The latter case was broken by refactoring in commit v3.12.0-rc1~160^2~7
(remove TargetIsCSharpOnly() and use methods from cmGeneratorTarget,
2018-03-19).  The reason is that the `HasLanguage` method added by
commit v3.12.0-rc1~239^2~6 (cmGeneratorTarget: add HasLanguage() as
wrapper for GetLanguages(), 2018-03-19) does not check the target type
and so is not a suitable check for deciding the project file extension.

The `HasLanguage` method was an attempt at an abstraction that turns
out not to work very well.  Replace it with a dedicated `IsCSharpOnly`
method that considers the target type, sources, and non-transitive
`LINKER_LANGUAGE`.

Fixes: #18515

1 files changed, 7 insertions, 9 deletions

diff --git a/Source/cmVisualStudio10TargetGenerator.cxx b/Source/cmVisualStudio10TargetGenerator.cxx
index 09c08d3..334c15b 100644
--- a/Source/cmVisualStudio10TargetGenerator.cxx
+++ b/Source/cmVisualStudio10TargetGenerator.cxx
@@ -215,12 +215,11 @@ static bool cmVS10IsTargetsFile(std::string const& path)
   return cmSystemTools::Strucmp(ext.c_str(), ".targets") == 0;
 }
 
-static std::string computeProjectFileExtension(cmGeneratorTarget const* t,
-                                               const std::string& config)
+static std::string computeProjectFileExtension(cmGeneratorTarget const* t)
 {
   std::string res;
   res = ".vcxproj";
-  if (t->HasLanguage("CSharp", config)) {
+  if (t->IsCSharpOnly()) {
     res = ".csproj";
   }
   return res;
@@ -315,8 +314,8 @@ void cmVisualStudio10TargetGenerator::Generate()
       this->GeneratorTarget->GetProperty("EXTERNAL_MSPROJECT")) {
     return;
   }
-  const std::string ProjectFileExtension = computeProjectFileExtension(
-    this->GeneratorTarget, *this->Configurations.begin());
+  const std::string ProjectFileExtension =
+    computeProjectFileExtension(this->GeneratorTarget);
   if (ProjectFileExtension == ".vcxproj") {
     this->ProjectType = vcxproj;
     this->Managed = false;
@@ -1409,8 +1408,7 @@ void cmVisualStudio10TargetGenerator::WriteGroups()
   std::string path = this->LocalGenerator->GetCurrentBinaryDirectory();
   path += "/";
   path += this->Name;
-  path += computeProjectFileExtension(this->GeneratorTarget,
-                                      *this->Configurations.begin());
+  path += computeProjectFileExtension(this->GeneratorTarget);
   path += ".filters";
   cmGeneratedFileStream fout(path);
   fout.SetCopyIfDifferent(true);
@@ -3812,7 +3810,7 @@ void cmVisualStudio10TargetGenerator::WriteProjectReferences(Elem& e0)
       path = lg->GetCurrentBinaryDirectory();
       path += "/";
       path += dt->GetName();
-      path += computeProjectFileExtension(dt, *this->Configurations.begin());
+      path += computeProjectFileExtension(dt);
     }
     ConvertToWindowsSlash(path);
     Elem e2(e1, "ProjectReference");
@@ -3838,7 +3836,7 @@ void cmVisualStudio10TargetGenerator::WriteProjectReferences(Elem& e0)
     }
     // Workaround for static library C# targets
     if (referenceNotManaged && dt->GetType() == cmStateEnums::STATIC_LIBRARY) {
-      referenceNotManaged = !dt->HasLanguage("CSharp", "");
+      referenceNotManaged = !dt->IsCSharpOnly();
     }
     if (referenceNotManaged) {
       e2.Element("ReferenceOutputAssembly", "false");