cmLocalGenerator: Refactor custom command generator construction

Add support for constructing and using multiple generators for one
custom command.  cmGeneratorTarget contains a code path that needs this
behavior when used with Ninja but not other generators, so use virtual
dispatch through cmLocalGenerator.

Source/cmGeneratorTarget.cxx

@@ -3079,8 +3079,8 @@ void cmTargetTraceDependencies::CheckCustomCommand(cmCustomCommand const& cc)
   std::set<std::string> depends;
   for (std::string const& config :
        this->Makefile->GetGeneratorConfigs(cmMakefile::IncludeEmptyConfig)) {
-    cmCustomCommandGenerator ccg(cc, config, this->LocalGenerator);
-
+    for (cmCustomCommandGenerator const& ccg :
+         this->LocalGenerator->MakeCustomCommandGenerators(cc, config)) {
       // Collect target-level dependencies referenced in command lines.
       for (auto const& util : ccg.GetUtilities()) {
         this->GeneratorTarget->Target->AddUtility(util);
@@ -3089,6 +3089,7 @@ void cmTargetTraceDependencies::CheckCustomCommand(cmCustomCommand const& cc)
       // Collect file-level dependencies referenced in DEPENDS.
       depends.insert(ccg.GetDepends().begin(), ccg.GetDepends().end());
     }
+  }
 
   // Queue file-level dependencies.
   for (std::string const& dep : depends) {

Source/cmLocalGenerator.cxx

@@ -4232,6 +4232,15 @@ cmSourceFile* cmLocalGenerator::GetSourceFileWithOutput(
   return nullptr;
 }
 
+std::vector<cmCustomCommandGenerator>
+cmLocalGenerator::MakeCustomCommandGenerators(cmCustomCommand const& cc,
+                                              std::string const& config)
+{
+  std::vector<cmCustomCommandGenerator> ccgs;
+  ccgs.emplace_back(cc, config, this);
+  return ccgs;
+}
+
 std::vector<std::string> cmLocalGenerator::ExpandCustomCommandOutputPaths(
   cmCompiledGeneratorExpression const& cge, std::string const& config)
 {

Source/cmLocalGenerator.h

@@ -24,6 +24,7 @@
 
 class cmCompiledGeneratorExpression;
 class cmComputeLinkInformation;
+class cmCustomCommand;
 class cmCustomCommandGenerator;
 class cmCustomCommandLines;
 class cmGeneratorTarget;
@@ -363,6 +364,9 @@ public:
     bool command_expand_lists = false, const std::string& job_pool = "",
     bool stdPipesUTF8 = false);
 
+  virtual std::vector<cmCustomCommandGenerator> MakeCustomCommandGenerators(
+    cmCustomCommand const& cc, std::string const& config);
+
   std::vector<std::string> ExpandCustomCommandOutputPaths(
     cmCompiledGeneratorExpression const& cge, std::string const& config);
   std::vector<std::string> ExpandCustomCommandOutputGenex(

Source/cmLocalNinjaGenerator.cxx

@@ -575,20 +575,8 @@ void cmLocalNinjaGenerator::WriteCustomCommandBuildStatement(
     return;
   }
 
-  bool transformDepfile = false;
-  auto cmp0116 = this->GetPolicyStatus(cmPolicies::CMP0116);
-  switch (cmp0116) {
-    case cmPolicies::OLD:
-    case cmPolicies::WARN:
-      break;
-    case cmPolicies::REQUIRED_IF_USED:
-    case cmPolicies::REQUIRED_ALWAYS:
-    case cmPolicies::NEW:
-      transformDepfile = true;
-      break;
-  }
-
-  cmCustomCommandGenerator ccg(*cc, config, this, transformDepfile);
+  for (cmCustomCommandGenerator const& ccg :
+       this->MakeCustomCommandGenerators(*cc, config)) {
 
     const std::vector<std::string>& outputs = ccg.GetOutputs();
     const std::vector<std::string>& byproducts = ccg.GetByproducts();
@@ -607,7 +595,8 @@ void cmLocalNinjaGenerator::WriteCustomCommandBuildStatement(
     std::transform(outputs.begin(), outputs.end(), ninjaOutputs.begin(),
                    gg->MapToNinjaPath());
     std::transform(byproducts.begin(), byproducts.end(),
-                 ninjaOutputs.begin() + outputs.size(), gg->MapToNinjaPath());
+                   ninjaOutputs.begin() + outputs.size(),
+                   gg->MapToNinjaPath());
 
     for (std::string const& ninjaOutput : ninjaOutputs) {
       gg->SeenCustomCommandOutput(ninjaOutput);
@@ -635,7 +624,7 @@ void cmLocalNinjaGenerator::WriteCustomCommandBuildStatement(
 
       std::string depfile = cc->GetDepfile();
       if (!depfile.empty()) {
-      switch (cmp0116) {
+        switch (this->GetPolicyStatus(cmPolicies::CMP0116)) {
           case cmPolicies::WARN:
             if (this->GetCurrentBinaryDirectory() !=
                   this->GetBinaryDirectory() ||
@@ -666,6 +655,28 @@ void cmLocalNinjaGenerator::WriteCustomCommandBuildStatement(
         /*restat*/ !symbolic || !byproducts.empty(), ninjaOutputs, config,
         ninjaDeps, orderOnlyDeps);
     }
+  }
+}
+
+std::vector<cmCustomCommandGenerator>
+cmLocalNinjaGenerator::MakeCustomCommandGenerators(cmCustomCommand const& cc,
+                                                   std::string const& config)
+{
+  bool transformDepfile = false;
+  switch (this->GetPolicyStatus(cmPolicies::CMP0116)) {
+    case cmPolicies::OLD:
+    case cmPolicies::WARN:
+      break;
+    case cmPolicies::REQUIRED_IF_USED:
+    case cmPolicies::REQUIRED_ALWAYS:
+    case cmPolicies::NEW:
+      transformDepfile = true;
+      break;
+  }
+
+  std::vector<cmCustomCommandGenerator> ccgs;
+  ccgs.emplace_back(cc, config, this, transformDepfile);
+  return ccgs;
 }
 
 void cmLocalNinjaGenerator::AddCustomCommandTarget(cmCustomCommand const* cc,

Source/cmLocalNinjaGenerator.h

@@ -70,6 +70,9 @@ public:
                            const std::string& fileConfig,
                            cmNinjaTargetDepends depends);
 
+  std::vector<cmCustomCommandGenerator> MakeCustomCommandGenerators(
+    cmCustomCommand const& cc, std::string const& config) override;
+
   void AddCustomCommandTarget(cmCustomCommand const* cc,
                               cmGeneratorTarget* target);
   void AppendCustomCommandLines(cmCustomCommandGenerator const& ccg,