ENH: fix build c stuff with c and c++ with c++

Source/cmLocalVisualStudio7Generator.cxx

@@ -262,6 +262,8 @@ cmVS7FlagTable cmLocalVisualStudio7GeneratorFlagTable[] =
   {"EnableEnhancedInstructionSet", "arch:SSE", "Use sse instructions",   "1"},
   {"FavorSizeOrSpeed",  "Ot", "Favor fast code",  "1"},
   {"FavorSizeOrSpeed",  "Os", "Favor small code", "2"},
+  {"CompileAs", "TC", "Compile as c code",        "1"},
+  {"CompileAs", "TP", "Compile as c++ code",      "2"},
   {"Optimization", "Od", "Non Debug",        "0"},
   {"Optimization", "O1", "Min Size",         "1"},
   {"Optimization", "O2", "Max Speed",        "2"},
@@ -395,6 +397,16 @@ void cmLocalVisualStudio7Generator::WriteConfiguration(std::ostream& fout,
       flags += " ";
       flags += this->Makefile->GetRequiredDefinition(flagVar.c_str());
       }
+    // set the correct language
+    if(strcmp(linkLanguage, "C") == 0)
+      {
+      flags += " /TC ";
+      }
+    if(strcmp(linkLanguage, "CXX") == 0)
+      {
+      flags += " /TP ";
+      }
+    std::cerr << flags << "\n";
     }
 
   // Add the target-specific flags.
@@ -1035,10 +1047,21 @@ void cmLocalVisualStudio7Generator::WriteGroup(const cmSourceGroup *sg, cmTarget
       }
     const char* lang =
       this->GlobalGenerator->GetLanguageFromExtension((*sf)->GetSourceExtension().c_str());
-    if(lang && strcmp(lang, "CXX") == 0)
+    const char* linkLanguage = target.GetLinkerLanguage(this->GetGlobalGenerator());
+    // if the source file does not match the linker language
+    // then force c or c++
+    if(linkLanguage && lang && strcmp(lang, linkLanguage) != 0)
       {
-      // force a C++ file type
-      compileFlags += " /TP ";
+      if(strcmp(lang, "CXX") == 0)
+        {
+        // force a C++ file type
+        compileFlags += " /TP ";
+        }
+      else if(strcmp(lang, "C") == 0)
+        {
+        // force to c 
+        compileFlags += " /TC ";
+        }
       }
     // Check for extra object-file dependencies.
     const char* deps = (*sf)->GetProperty("OBJECT_DEPENDS");

Tests/COnly/conly.c

@@ -7,6 +7,7 @@
 
 int main ()
 {
+  int class = 0;
   if ( LibC1Func() != 2.0 )
     {
     printf("Problem with libc1\n");
@@ -17,6 +18,6 @@ int main ()
     printf("Problem with libc2\n");
     return 1;
     }
-  printf("Foo: %s\n", foo);
+  printf("Foo: %s %d\n", foo, class);
   return 0;
 }