VS: Support mapping flags with values following separately (#14858)

Add a "UserFollowing" special flag table entry indicator to say that a
flag expects a value in a following argument.  Teach cmIDEOptions to
handle such flags.

Source/cmIDEFlagTable.h

@@ -31,6 +31,7 @@ struct cmIDEFlagTable
                                   // old value with semicolons (e.g.
                                   // /NODEFAULTLIB: =>
                                   // IgnoreDefaultLibraryNames)
+    UserFollowing = (1<<5), // expect value in following argument
 
     UserValueIgnored  = UserValue | UserIgnored,
     UserValueRequired = UserValue | UserRequired

Source/cmIDEOptions.cxx

@@ -19,6 +19,7 @@ cmIDEOptions::cmIDEOptions()
   this->DoingDefine = false;
   this->AllowDefine = true;
   this->AllowSlash = false;
+  this->DoingFollowing = 0;
   for(int i=0; i < FlagTableCount; ++i)
     {
     this->FlagTable[i] = 0;
@@ -41,6 +42,14 @@ void cmIDEOptions::HandleFlag(const char* flag)
     return;
     }
 
+  // If the last option expected a following value, this is it.
+  if(this->DoingFollowing)
+    {
+    this->FlagMapUpdate(this->DoingFollowing, flag);
+    this->DoingFollowing = 0;
+    return;
+    }
+
   // Look for known arguments.
   if(flag[0] == '-' || (this->AllowSlash && flag[0] == '/'))
     {
@@ -104,9 +113,17 @@ bool cmIDEOptions::CheckFlagTable(cmIDEFlagTable const* table,
         }
       }
     else if(strcmp(flag+1, entry->commandFlag) == 0)
+      {
+      if(entry->special & cmIDEFlagTable::UserFollowing)
+        {
+        // This flag expects a value in the following argument.
+        this->DoingFollowing = entry;
+        }
+      else
         {
         // This flag table entry provides a fixed value.
         this->FlagMap[entry->IDEName] = entry->value;
+        }
       entry_found = true;
       }
 

Source/cmIDEOptions.h

@@ -51,6 +51,7 @@ protected:
   bool DoingDefine;
   bool AllowDefine;
   bool AllowSlash;
+  cmIDEFlagTable const* DoingFollowing;
   enum { FlagTableCount = 16 };
   cmIDEFlagTable const* FlagTable[FlagTableCount];
   void HandleFlag(const char* flag);