1 files changed, 67 insertions, 36 deletions

diff --git a/Source/cmListFileCache.h b/Source/cmListFileCache.h
index 349ddef91..9cae8277b 100644
--- a/Source/cmListFileCache.h
+++ b/Source/cmListFileCache.h
@@ -5,8 +5,11 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
+#include <cstddef>
 #include <iosfwd>
+#include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "cmStateSnapshot.h"
@@ -22,11 +25,19 @@ class cmMessenger;
 
 struct cmCommandContext
 {
-  std::string Name;
-  long Line;
-  cmCommandContext()
-    : Name()
-    , Line(0)
+  struct cmCommandName
+  {
+    std::string Lower;
+    std::string Original;
+    cmCommandName() = default;
+    cmCommandName(std::string const& name) { *this = name; }
+    cmCommandName& operator=(std::string const& name);
+  } Name;
+  long Line = 0;
+  cmCommandContext() = default;
+  cmCommandContext(const char* name, int line)
+    : Name(name)
+    , Line(line)
   {
   }
 };
@@ -39,14 +50,9 @@ struct cmListFileArgument
     Quoted,
     Bracket
   };
-  cmListFileArgument()
-    : Value()
-    , Delim(Unquoted)
-    , Line(0)
-  {
-  }
-  cmListFileArgument(const std::string& v, Delimiter d, long line)
-    : Value(v)
+  cmListFileArgument() = default;
+  cmListFileArgument(std::string v, Delimiter d, long line)
+    : Value(std::move(v))
     , Delim(d)
     , Line(line)
   {
@@ -57,8 +63,8 @@ struct cmListFileArgument
   }
   bool operator!=(const cmListFileArgument& r) const { return !(*this == r); }
   std::string Value;
-  Delimiter Delim;
-  long Line;
+  Delimiter Delim = Unquoted;
+  long Line = 0;
 };
 
 class cmListFileContext
@@ -66,13 +72,7 @@ class cmListFileContext
 public:
   std::string Name;
   std::string FilePath;
-  long Line;
-  cmListFileContext()
-    : Name()
-    , FilePath()
-    , Line(0)
-  {
-  }
+  long Line = 0;
 
   static cmListFileContext FromCommandContext(cmCommandContext const& lfcc,
                                               std::string const& fileName)
@@ -80,7 +80,7 @@ public:
     cmListFileContext lfc;
     lfc.FilePath = fileName;
     lfc.Line = lfcc.Line;
-    lfc.Name = lfcc.Name;
+    lfc.Name = lfcc.Name.Original;
     return lfc;
   }
 };
@@ -103,18 +103,13 @@ public:
   // Default-constructed backtrace may not be used until after
   // set via assignment from a backtrace constructed with a
   // valid snapshot.
-  cmListFileBacktrace();
+  cmListFileBacktrace() = default;
 
   // Construct an empty backtrace whose bottom sits in the directory
   // indicated by the given valid snapshot.
   cmListFileBacktrace(cmStateSnapshot const& snapshot);
 
-  // Backtraces may be copied and assigned as values.
-  cmListFileBacktrace(cmListFileBacktrace const& r);
-  cmListFileBacktrace& operator=(cmListFileBacktrace const& r);
-  ~cmListFileBacktrace();
-
-  cmStateSnapshot GetBottom() const { return this->Bottom; }
+  cmStateSnapshot GetBottom() const;
 
   // Get a backtrace with the given file scope added to the top.
   // May not be called until after construction with a valid snapshot.
@@ -129,7 +124,7 @@ public:
   cmListFileBacktrace Pop() const;
 
   // Get the context at the top of the backtrace.
-  // Returns an empty context if the backtrace is empty.
+  // This may be called only if Empty() would return false.
   cmListFileContext const& Top() const;
 
   // Print the top of the backtrace.
@@ -138,16 +133,52 @@ public:
   // Print the call stack below the top of the backtrace.
   void PrintCallStack(std::ostream& out) const;
 
+  // Get the number of 'frames' in this backtrace
+  size_t Depth() const;
+
+  // Return true if this backtrace is empty.
+  bool Empty() const;
+
 private:
   struct Entry;
-
-  cmStateSnapshot Bottom;
-  Entry* Cur;
-  cmListFileBacktrace(cmStateSnapshot const& bottom, Entry* up,
+  std::shared_ptr<Entry const> TopEntry;
+  cmListFileBacktrace(std::shared_ptr<Entry const> parent,
                       cmListFileContext const& lfc);
-  cmListFileBacktrace(cmStateSnapshot const& bottom, Entry* cur);
+  cmListFileBacktrace(std::shared_ptr<Entry const> top);
 };
 
+// Wrap type T as a value with a backtrace.  For purposes of
+// ordering and equality comparison, only the original value is
+// used.  The backtrace is considered incidental.
+template <typename T>
+class BT
+{
+public:
+  BT(T v = T(), cmListFileBacktrace bt = cmListFileBacktrace())
+    : Value(std::move(v))
+    , Backtrace(std::move(bt))
+  {
+  }
+  T Value;
+  cmListFileBacktrace Backtrace;
+  friend bool operator==(BT<T> const& l, BT<T> const& r)
+  {
+    return l.Value == r.Value;
+  }
+  friend bool operator<(BT<T> const& l, BT<T> const& r)
+  {
+    return l.Value < r.Value;
+  }
+  friend bool operator==(BT<T> const& l, T const& r) { return l.Value == r; }
+  friend bool operator==(T const& l, BT<T> const& r) { return l == r.Value; }
+};
+
+std::ostream& operator<<(std::ostream& os, BT<std::string> const& s);
+
+std::vector<BT<std::string>> ExpandListWithBacktrace(
+  std::string const& list,
+  cmListFileBacktrace const& bt = cmListFileBacktrace());
+
 struct cmListFile
 {
   bool ParseFile(const char* path, cmMessenger* messenger,