custom rule: enhance output file set management

* Add control over output file set BASE_DIRS
* Add patterns for output file set directories

Help/command/add_custom_rule.rst

@@ -53,8 +53,10 @@ Generating Files
   custom command will be declared as part of a file set attached to
   the same target. The type of this file set, as well as its name, are
   controlled by the :prop_rule:`OUTPUT_FILE_SET` rule property. This output
-  file set will have the same scope (``PRIVATE``, ``PUBLIC``, or ``INTERFACE``)
-  as the input file set.
+  file set will be created in the same directory and will have the same scope
+  (``PRIVATE``, ``PUBLIC``, or ``INTERFACE``) as the input file set. The base
+  directories can be specified by the :prop_rule:`OUTPUT_FILE_SET_BASE_DIRS`
+  rule property.
 
   To parameterize the template, some patterns are defined which can be used as
   part of the ``add_custom_rule`` arguments as well as the :ref:`rule's
@@ -90,6 +92,12 @@ Generating Files
   ``<CURRENT_BINARY_DIR>``
     The path to the binary directory of the file set creation.
 
+  ``<OUTPUT_CURRENT_SOURCE_DIR>``
+    The path to the source directory of the output file set creation.
+
+  ``<OUTPUT_CURRENT_BINARY_DIR>``
+    The path to the binary directory of the output file set creation.
+
   ``<SOURCE>``
     The full path of the current source file being processed.
 

Help/manual/cmake-properties.7.rst

@@ -131,6 +131,7 @@ Properties on Rules
    /prop_rule/NAME
    /prop_rule/OUTPUT
    /prop_rule/OUTPUT_FILE_SET
+   /prop_rule/OUTPUT_FILE_SET_BASE_DIRS
    /prop_rule/PARENT_RULE
    /prop_rule/SOURCE_CONFIGURATORS
    /prop_rule/USES_TERMINAL

Help/prop_rule/OUTPUT_FILE_SET_BASE_DIRS.rst

@@ -0,0 +1,29 @@
+OUTPUT_FILE_SET_BASE_DIRS
+-------------------------
+
+.. versionadded:: 4.5
+
+Specify the base directories for the output file set.
+
+The ``OUTPUT_FILE_SET_BASE_DIRS`` may be set to a
+:ref:`semicolon-separated list <CMake Language Lists>` of directories.
+
+The directories can use the following patterns:
+
+* ``<RULE>``: name of the rule
+* ``<TARGET>``: name of the target
+* ``<FILE_SET>``: name of the file set
+* ``<CURRENT_SOURCE_DIR>``: path to the source directory of the file set
+  creation
+* ``<CURRENT_BINARY_DIR>``: path to the binary directory of the file set
+  creation
+* ``<OUTPUT_CURRENT_SOURCE_DIR>``: path to the source directory of the output
+  file set creation
+* ``<OUTPUT_CURRENT_BINARY_DIR>``: path to the binary directory of the output
+  file set creation
+
+This property gets the following default value: ``<CURRENT_BINARY_DIR>``.
+
+Contents of ``OUTPUT_FILE_SET_BASE_DIRS`` may use generator expressions with
+the syntax ``$<...>``. See the cmake-buildsystem(7) manual for more on defining
+buildsystem properties.

Source/cmGeneratorRule.cxx

@@ -36,6 +36,8 @@ std::vector<cm::string_view> ReservedPatterns{ "RULE"_s,
                                                "BINARY_DIR"_s,
                                                "CURRENT_SOURCE_DIR"_s,
                                                "CURRENT_BINARY_DIR"_s,
+                                               "OUTPUT_CURRENT_SOURCE_DIR"_s,
+                                               "OUTPUT_CURRENT_BINARY_DIR"_s,
                                                "SOURCE"_s,
                                                "INPUT_DIR"_s,
                                                "FILE_NAME"_s,
@@ -107,6 +109,8 @@ cmGeneratorRule::cmGeneratorRule(cmRule const* rule, cmTarget const* target,
   values.insert({ "BINARY_DIR", this->GetMakefile().GetHomeOutputDirectory() });
   values.insert({ "CURRENT_SOURCE_DIR", this->GetMakefile().GetCurrentSourceDirectory() });
   values.insert({ "CURRENT_BINARY_DIR", this->GetMakefile().GetCurrentBinaryDirectory() });
+  values.insert({ "OUTPUT_CURRENT_SOURCE_DIR", outputFileSet->GetMakefile()->GetCurrentSourceDirectory() });
+  values.insert({ "OUTPUT_CURRENT_BINARY_DIR", outputFileSet->GetMakefile()->GetCurrentBinaryDirectory() });
   values.insert({ "SOURCE", file.GenericString() });
   values.insert({ "INPUT_DIR", file.GetParentPath().GenericString() });
   values.insert({ "FILE_NAME", file.GetFileName().GenericString() });
@@ -306,9 +310,6 @@ std::unique_ptr<cmCustomCommand> cmGeneratorRule::Generate(
   // populate file set with outputs from custom command
   for (auto const& output : cc->GetOutputs()) {
     outFileSet->AddFileEntry(BT<std::string>{ output });
-    // get the directory of the generated file
-    outFileSet->AddDirectoryEntry(
-      BT<std::string>{ cmStrCat("$<PATH:GET_PARENT_PATH,", output, '>') });
   }
 
   return cc;

Source/cmRule.cxx

@@ -47,6 +47,8 @@ cm::string_view const INCLUDE_DIRECTORIES = "INCLUDE_DIRECTORIES"_s;
 cm::string_view const JOB_POOL_COMPILE = "JOB_POOL_COMPILE"_s;
 cm::string_view const JOB_SERVER_AWARE = "JOB_SERVER_AWARE"_s;
 cm::string_view const OUTPUT_FILE_SET = "OUTPUT_FILE_SET"_s;
+cm::string_view const OUTPUT_FILE_SET_BASE_DIRS =
+  "OUTPUT_FILE_SET_BASE_DIRS"_s;
 cm::string_view const PARENT_RULE = "PARENT_RULE"_s;
 cm::string_view const FILE_SET_CONFIGURATORS = "FILE_SET_CONFIGURATORS"_s;
 cm::string_view const SOURCE_CONFIGURATORS = "SOURCE_CONFIGURATORS"_s;
@@ -126,6 +128,7 @@ bool IsSettableProperty(cm::string_view prop, cmRule const* rule)
                    { JOB_POOL_COMPILE, { ROC::Generation } },
                    { JOB_SERVER_AWARE, { ROC::Generation } },
                    { OUTPUT_FILE_SET, { ROC::Generation } },
+                   { OUTPUT_FILE_SET_BASE_DIRS, { ROC::Generation } },
                    { PARENT_RULE, { ROC::All } },
                    { FILE_SET_CONFIGURATORS, { ROC::All } },
                    { SOURCE_CONFIGURATORS, { ROC::All } },
@@ -182,6 +185,7 @@ cmRule::cmRule(cmMakefile& makefile, std::string name, cm::RuleScope scope)
   this->SetProperty("COMMAND_EXPAND_LISTS", cmValue::True);
   this->SetProperty("OUTPUT_FILE_SET",
                     "__cmake_rule_<RULE>_<TARGET>_<FILE_SET>_outputs;SOURCES");
+  this->SetProperty("OUTPUT_FILE_SET_BASE_DIRS", "<CURRENT_BINARY_DIR>");
 }
 
 cmRule::cmRule(cmRule const& parent, cmMakefile& makefile, std::string name,
@@ -265,6 +269,27 @@ cmFileSet* cmRule::GetOutputFileSet(cmTarget* target,
     return nullptr;
   }
 
+  if (result.first->GetDirectoryEntries().empty()) {
+    if (cmValue baseDirs =
+          this->GetProperty(std::string{ OUTPUT_FILE_SET_BASE_DIRS })) {
+      expander.Values["CURRENT_SOURCE_DIR"] =
+        fileSet->GetMakefile()->GetCurrentSourceDirectory();
+      expander.Values["CURRENT_BINARY_DIR"] =
+        fileSet->GetMakefile()->GetCurrentBinaryDirectory();
+      expander.Values["OUTPUT_CURRENT_SOURCE_DIR"] =
+        result.first->GetMakefile()->GetCurrentSourceDirectory();
+      expander.Values["OUTPUT_CURRENT_BINARY_DIR"] =
+        result.first->GetMakefile()->GetCurrentBinaryDirectory();
+      std::string dirs{ baseDirs };
+      expander.ExpandVariables(dirs);
+      result.first->AddDirectoryEntry(BT<std::string>{ dirs });
+    } else {
+      // Add default base directory if none are specified
+      result.first->AddDirectoryEntry(BT<std::string>{
+        fileSet->GetMakefile()->GetCurrentBinaryDirectory() });
+    }
+  }
+
   return result.first;
 }