Add API to check that dependent target properties form a DAG.

Initially this will only be used to check for self-references, but
can be extended to check for cycles when chaining properties of other
targets.

1 files changed, 106 insertions, 0 deletions

diff --git a/Source/cmGeneratorExpressionDAGChecker.cxx b/Source/cmGeneratorExpressionDAGChecker.cxx
new file mode 100644
index 0000000..bfb0ddf
--- /dev/null
+++ b/Source/cmGeneratorExpressionDAGChecker.cxx
@@ -0,0 +1,106 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2012 Stephen Kelly <steveire@gmail.com>
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+
+#include "cmGeneratorExpressionDAGChecker.h"
+
+#include "cmMakefile.h"
+
+//----------------------------------------------------------------------------
+cmGeneratorExpressionDAGChecker::cmGeneratorExpressionDAGChecker(
+                const cmListFileBacktrace &backtrace,
+                const std::string &target,
+                const std::string &property,
+                const GeneratorExpressionContent *content,
+                cmGeneratorExpressionDAGChecker *parent)
+  : Parent(parent), Target(target), Property(property),
+    Content(content), Backtrace(backtrace)
+{
+  this->IsDAG = this->isDAG();
+}
+
+//----------------------------------------------------------------------------
+bool cmGeneratorExpressionDAGChecker::check() const
+{
+  return this->IsDAG;
+}
+
+//----------------------------------------------------------------------------
+void cmGeneratorExpressionDAGChecker::reportError(
+                  cmGeneratorExpressionContext *context,
+                  const std::string &expr)
+{
+  if (this->IsDAG)
+    {
+    return;
+    }
+
+  context->HadError = true;
+  if (context->Quiet)
+    {
+    return;
+    }
+
+  const cmGeneratorExpressionDAGChecker *parent = this->Parent;
+
+  if (parent && !parent->Parent)
+    {
+    cmOStringStream e;
+    e << "Error evaluating generator expression:\n"
+      << "  " << expr << "\n"
+      << "Self reference on target \""
+      << context->Target->GetName() << "\".\n";
+    context->Makefile->GetCMakeInstance()
+      ->IssueMessage(cmake::FATAL_ERROR, e.str().c_str(),
+                      parent->Backtrace);
+    return;
+    }
+
+  {
+  cmOStringStream e;
+  e << "Error evaluating generator expression:\n"
+    << "  " << expr << "\n"
+    << "Dependency loop found.";
+  context->Makefile->GetCMakeInstance()
+    ->IssueMessage(cmake::FATAL_ERROR, e.str().c_str(),
+                    context->Backtrace);
+  }
+
+  int loopStep = 1;
+  while (parent)
+    {
+    cmOStringStream e;
+    e << "Loop step " << loopStep << "\n"
+      << "  "
+      << (parent->Content ? parent->Content->GetOriginalExpression() : expr)
+      << "\n";
+    context->Makefile->GetCMakeInstance()
+      ->IssueMessage(cmake::FATAL_ERROR, e.str().c_str(),
+                      parent->Backtrace);
+    parent = parent->Parent;
+    ++loopStep;
+    }
+}
+
+//----------------------------------------------------------------------------
+bool cmGeneratorExpressionDAGChecker::isDAG() const
+{
+  const cmGeneratorExpressionDAGChecker *parent = this->Parent;
+  while (parent)
+    {
+    if (this->Target == parent->Target && this->Property == parent->Property)
+      {
+      return false;
+      }
+    parent = parent->Parent;
+    }
+  return true;
+}