file(GENERATE): Evaluate early to allow generating source files

The evaluation files must be known before cmTargetTraceDependencies
attempts to find them, but we must actually generate the files after
cmTargetTraceDependencies, as that can add to target SOURCES.  The
limitation is that the generated output name must not depend on the
SOURCES of a target if the generated file is used by that target.

Mark the output files as GENERATED so that trace dependencies does
not expect them to already exist in the filesystem.

Move the invokation of ForceLinkerLanguage in the Generate logic
to after the generated file names are known.  ForceLinkerLanguage
tries to determine the sources of a target (in order to determine
an already-known language) and otherwise fails to get information
about the generated file.

Test that the output of file(GENERATE) can be used as a target source
file and that accessing the target SOURCES in the name of the output
file is an error.  Accessing the TARGET_OBJECTS would be a similar
error if it was legal to use that generator expression in this
context.  That is not currently possible and is a different error
condition, so test the current error output as a reminder to change
the expected output if that becomes possible in the future.  Test
that generated rule files resulting from cmTargetTraceDependencies
appear in the SOURCES generated in the output file.

Source/cmGeneratorExpression.cxx

@@ -90,6 +90,7 @@ const char *cmCompiledGeneratorExpression::Evaluate(
   context.HadError = false;
   context.HadContextSensitiveCondition = false;
   context.HadHeadSensitiveCondition = false;
+  context.SourceSensitiveTargets.clear();
   context.HeadTarget = headTarget;
   context.EvaluateForBuildsystem = this->EvaluateForBuildsystem;
   context.CurrentTarget = currentTarget ? currentTarget : headTarget;
@@ -118,6 +119,7 @@ const char *cmCompiledGeneratorExpression::Evaluate(
     {
     this->HadContextSensitiveCondition = context.HadContextSensitiveCondition;
     this->HadHeadSensitiveCondition = context.HadHeadSensitiveCondition;
+    this->SourceSensitiveTargets = context.SourceSensitiveTargets;
     }
 
   this->DependTargets = context.DependTargets;

Source/cmGeneratorExpression.h

@@ -115,6 +115,10 @@ public:
   {
     return this->HadHeadSensitiveCondition;
   }
+  std::set<cmTarget const*> GetSourceSensitiveTargets() const
+  {
+    return this->SourceSensitiveTargets;
+  }
 
   void SetEvaluateForBuildsystem(bool eval)
   {
@@ -146,6 +150,7 @@ private:
   mutable std::string Output;
   mutable bool HadContextSensitiveCondition;
   mutable bool HadHeadSensitiveCondition;
+  mutable std::set<cmTarget const*>  SourceSensitiveTargets;
   bool EvaluateForBuildsystem;
 };
 

Source/cmGeneratorExpressionEvaluationFile.cxx

@@ -13,6 +13,9 @@
 #include "cmGeneratorExpressionEvaluationFile.h"
 
 #include "cmMakefile.h"
+#include "cmLocalGenerator.h"
+#include "cmGlobalGenerator.h"
+#include "cmSourceFile.h"
 #include "cmGeneratedFileStream.h"
 #include <cmsys/FStream.hxx>
 
@@ -89,6 +92,20 @@ void cmGeneratorExpressionEvaluationFile::Generate(const std::string& config,
     }
 }
 
+//----------------------------------------------------------------------------
+void cmGeneratorExpressionEvaluationFile::CreateOutputFile(
+                                              std::string const& config)
+{
+  std::string name = this->OutputFileExpr->Evaluate(this->Makefile, config);
+  cmSourceFile* sf = this->Makefile->GetOrCreateSource(name);
+  sf->SetProperty("GENERATED", "1");
+
+  cmGlobalGenerator *gg
+                  = this->Makefile->GetLocalGenerator()->GetGlobalGenerator();
+  gg->SetFilenameTargetDepends(sf,
+                          this->OutputFileExpr->GetSourceSensitiveTargets());
+}
+
 //----------------------------------------------------------------------------
 void cmGeneratorExpressionEvaluationFile::Generate()
 {

Source/cmGeneratorExpressionEvaluationFile.h

@@ -31,6 +31,8 @@ public:
 
   std::vector<std::string> GetFiles() const { return this->Files; }
 
+  void CreateOutputFile(std::string const& config);
+
 private:
   void Generate(const std::string& config,
               cmCompiledGeneratorExpression* inputExpression,

Source/cmGeneratorExpressionEvaluator.cxx

@@ -950,6 +950,10 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
       // value for all evaluations.
       context->SeenTargetProperties.insert(propertyName);
       }
+    if (propertyName == "SOURCES")
+      {
+      context->SourceSensitiveTargets.insert(target);
+      }
 
     if (propertyName.empty())
       {

Source/cmGeneratorExpressionEvaluator.h

@@ -31,6 +31,7 @@ struct cmGeneratorExpressionContext
   std::set<cmTarget*> DependTargets;
   std::set<cmTarget const*> AllTargets;
   std::set<std::string> SeenTargetProperties;
+  std::set<cmTarget const*> SourceSensitiveTargets;
   std::map<cmTarget const*, std::map<std::string, std::string> >
                                                           MaxLanguageStandard;
   cmMakefile *Makefile;

Source/cmGeneratorTarget.cxx

@@ -646,6 +646,17 @@ cmTargetTraceDependencies
           si != sources.end(); ++si)
         {
         cmSourceFile* sf = *si;
+        const std::set<cmTarget const*> tgts =
+                          this->GlobalGenerator->GetFilenameTargetDepends(sf);
+        if (tgts.find(this->Target) != tgts.end())
+          {
+          cmOStringStream e;
+          e << "Evaluation output file\n  \"" << sf->GetFullPath()
+            << "\"\ndepends on the sources of a target it is used in.  This "
+              "is a dependency loop and is not allowed.";
+          this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
+          return;
+          }
         if(emitted.insert(sf).second && this->SourcesQueued.insert(sf).second)
           {
           this->SourceQueue.push(sf);

Source/cmGlobalGenerator.cxx

@@ -1253,8 +1253,6 @@ void cmGlobalGenerator::Generate()
   // Create per-target generator information.
   this->CreateGeneratorTargets();
 
-  this->ForceLinkerLanguages();
-
 #ifdef CMAKE_BUILD_WITH_CMAKE
   for (AutogensType::iterator it = autogens.begin(); it != autogens.end();
        ++it)
@@ -1270,6 +1268,8 @@ void cmGlobalGenerator::Generate()
     this->LocalGenerators[i]->TraceDependencies();
     }
 
+  this->ForceLinkerLanguages();
+
   // Compute the manifest of main targets generated.
   for (i = 0; i < this->LocalGenerators.size(); ++i)
     {
@@ -2982,6 +2982,32 @@ std::string cmGlobalGenerator::EscapeJSON(const std::string& s) {
   return result;
 }
 
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::SetFilenameTargetDepends(cmSourceFile* sf,
+                                              std::set<cmTarget const*> tgts)
+{
+  this->FilenameTargetDepends[sf] = tgts;
+}
+
+//----------------------------------------------------------------------------
+std::set<cmTarget const*> const&
+cmGlobalGenerator::GetFilenameTargetDepends(cmSourceFile* sf) const {
+  return this->FilenameTargetDepends[sf];
+}
+
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::CreateEvaluationSourceFiles(
+                                              std::string const& config) const
+{
+  for(std::vector<cmGeneratorExpressionEvaluationFile*>::const_iterator
+      li = this->EvaluationFiles.begin();
+      li != this->EvaluationFiles.end();
+      ++li)
+    {
+    (*li)->CreateOutputFile(config);
+    }
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalGenerator::AddEvaluationFile(const std::string &inputFile,
                     cmsys::auto_ptr<cmCompiledGeneratorExpression> outputExpr,

Source/cmGlobalGenerator.h

@@ -341,6 +341,13 @@ public:
 
   bool GenerateCPackPropertiesFile();
 
+  void CreateEvaluationSourceFiles(std::string const& config) const;
+
+  void SetFilenameTargetDepends(cmSourceFile* sf,
+                                std::set<cmTarget const*> tgts);
+  std::set<cmTarget const*> const&
+  GetFilenameTargetDepends(cmSourceFile* sf) const;
+
 protected:
   virtual void Generate();
 
@@ -488,6 +495,9 @@ private:
 
   // track targets to issue CMP0042 warning for.
   std::set<std::string> CMP0042WarnTargets;
+
+  mutable std::map<cmSourceFile*, std::set<cmTarget const*> >
+  FilenameTargetDepends;
 };
 
 #endif

Source/cmLocalGenerator.cxx

@@ -259,6 +259,17 @@ void cmLocalGenerator::ConfigureFinalPass()
 
 void cmLocalGenerator::TraceDependencies()
 {
+  std::vector<std::string> configs;
+  this->Makefile->GetConfigurations(configs);
+  if (configs.empty())
+    {
+    configs.push_back("");
+    }
+  for(std::vector<std::string>::const_iterator ci = configs.begin();
+      ci != configs.end(); ++ci)
+    {
+    this->GlobalGenerator->CreateEvaluationSourceFiles(*ci);
+    }
   // Generate the rule files for each target.
   cmGeneratorTargetsType targets = this->Makefile->GetGeneratorTargets();
   for(cmGeneratorTargetsType::iterator t = targets.begin();

Tests/RunCMake/File_Generate/GenerateSource-result.txt

@@ -0,0 +1 @@
+0

Tests/RunCMake/File_Generate/GenerateSource-stderr.txt

@@ -0,0 +1 @@
+^$

Tests/RunCMake/File_Generate/GenerateSource.cmake

@@ -0,0 +1,12 @@
+
+enable_language(CXX)
+
+# Ensure re-generation
+file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/main.cpp")
+
+file(GENERATE
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/main.cpp"
+  CONTENT "int main() { return 0; }\n"
+)
+
+add_executable(mn "${CMAKE_CURRENT_BINARY_DIR}/main.cpp")

Tests/RunCMake/File_Generate/OutputNameMatchesObjects-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/File_Generate/OutputNameMatchesObjects-stderr.txt

@@ -0,0 +1,9 @@
+CMake Error at OutputNameMatchesObjects.cmake:2 \(file\):
+  Error evaluating generator expression:
+
+    \$<TARGET_OBJECTS:foo>
+
+  The evaluation of the TARGET_OBJECTS generator expression is only suitable
+  for consumption by CMake.  It is not suitable for writing out elsewhere.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:6 \(include\)

Tests/RunCMake/File_Generate/OutputNameMatchesObjects.cmake

@@ -0,0 +1,10 @@
+
+file(GENERATE
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/$<BOOL:$<TARGET_OBJECTS:foo>>somefile.cpp"
+  CONTENT "static const char content[] = \"$<TARGET_OBJECTS:foo>\";\n"
+)
+
+add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/input.txt"
+  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_SOURCE_DIR}/input.txt" "${CMAKE_CURRENT_BINARY_DIR}")
+
+add_executable(foo empty.cpp "${CMAKE_CURRENT_BINARY_DIR}/1somefile.cpp" "${CMAKE_CURRENT_BINARY_DIR}/input.txt")

Tests/RunCMake/File_Generate/OutputNameMatchesOtherSources-result.txt

@@ -0,0 +1 @@
+0

Tests/RunCMake/File_Generate/OutputNameMatchesOtherSources-stderr.txt

@@ -0,0 +1 @@
+^$

Tests/RunCMake/File_Generate/OutputNameMatchesOtherSources.cmake

@@ -0,0 +1,14 @@
+
+enable_language(CXX)
+
+file(GENERATE
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/$<BOOL:$<TARGET_PROPERTY:foo,SOURCES>>somefile.cpp"
+  CONTENT "static const char content[] = \"$<TARGET_PROPERTY:foo,SOURCES>\";\n"
+)
+
+add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/generated.cpp"
+  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_SOURCE_DIR}/generated.cpp" "${CMAKE_CURRENT_BINARY_DIR}")
+
+add_executable(foo empty.cpp "${CMAKE_CURRENT_BINARY_DIR}/generated.cpp")
+
+add_executable(bar "${CMAKE_CURRENT_BINARY_DIR}/1somefile.cpp")

Tests/RunCMake/File_Generate/OutputNameMatchesSources-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/File_Generate/OutputNameMatchesSources-stderr.txt

@@ -0,0 +1,7 @@
+CMake Error in CMakeLists.txt:
+  Evaluation output file
+
+    ".*Tests/RunCMake/File_Generate/OutputNameMatchesSources-build/1somefile.cpp"
+
+  depends on the sources of a target it is used in.  This is a dependency
+  loop and is not allowed.

Tests/RunCMake/File_Generate/OutputNameMatchesSources.cmake

@@ -0,0 +1,12 @@
+
+enable_language(CXX)
+
+file(GENERATE
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/$<BOOL:$<TARGET_PROPERTY:foo,SOURCES>>somefile.cpp"
+  CONTENT "static const char content[] = \"$<TARGET_PROPERTY:foo,SOURCES>\";\n"
+)
+
+add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/renamed.cpp"
+  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp" "${CMAKE_CURRENT_BINARY_DIR}/renamed.cpp")
+
+add_executable(foo "${CMAKE_CURRENT_BINARY_DIR}/1somefile.cpp" "${CMAKE_CURRENT_BINARY_DIR}/renamed.cpp")

Tests/RunCMake/File_Generate/RunCMakeTest.cmake

@@ -8,6 +8,14 @@ run_cmake(EmptyCondition1)
 run_cmake(EmptyCondition2)
 run_cmake(BadCondition)
 run_cmake(DebugEvaluate)
+run_cmake(GenerateSource)
+run_cmake(OutputNameMatchesSources)
+run_cmake(OutputNameMatchesObjects)
+run_cmake(OutputNameMatchesOtherSources)
+file(READ "${RunCMake_BINARY_DIR}/OutputNameMatchesOtherSources-build/1somefile.cpp" file_contents)
+if (NOT file_contents MATCHES "generated.cpp.rule")
+  message(SEND_ERROR "Rule file not in target sources! ${file_contents}")
+endif()
 
 set(timeformat "%Y%j%H%M%S")
 

Tests/RunCMake/File_Generate/empty.cpp

@@ -0,0 +1,7 @@
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int empty()
+{
+  return 0;
+}