Add target properties to discover target's file set information

Currently, target properties related to file sets are specific to file set
type (for example "SOURCE_SETS"). This raises some concerns:
1. For each new file set type, 6 new properties are created which need a lot
   off documentation update
2. there is no "generic" way to discover file sets information

The new target properties (FILE_SET_TYPES, FILE_SETS_<TYPE>,
and INTERFACE_FILE_SETS_<TYPE>), in conjunction with the file sets
properties, enable a complete generic file sets information discovery.

Help/manual/cmake-properties.7.rst

@@ -227,6 +227,8 @@ Properties on Targets
    /prop_tgt/EXPORT_PROPERTIES
    /prop_tgt/FASTBUILD_CACHING
    /prop_tgt/FASTBUILD_DISTRIBUTION
+   /prop_tgt/FILE_SET_TYPES
+   /prop_tgt/FILE_SETS_TYPE
    /prop_tgt/FOLDER
    /prop_tgt/Fortran_BUILDING_INTRINSIC_MODULES
    /prop_tgt/Fortran_FORMAT
@@ -295,6 +297,7 @@ Properties on Targets
    /prop_tgt/INTERFACE_COMPILE_FEATURES
    /prop_tgt/INTERFACE_COMPILE_OPTIONS
    /prop_tgt/INTERFACE_CXX_MODULE_SETS
+   /prop_tgt/INTERFACE_FILE_SETS_TYPE
    /prop_tgt/INTERFACE_HEADER_SETS
    /prop_tgt/INTERFACE_HEADER_SETS_TO_VERIFY
    /prop_tgt/INTERFACE_INCLUDE_DIRECTORIES

Help/prop_tgt/CXX_MODULE_SETS.rst

@@ -7,8 +7,17 @@ Read-only list of the target's ``PRIVATE`` and ``PUBLIC`` C++ module sets (i.e.
 all file sets with the type ``CXX_MODULES``). Files listed in these file sets
 are treated as source files for the purpose of IDE integration.
 
-C++ module sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``CXX_MODULES``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`CXX_MODULE_SET_<NAME>`, :prop_tgt:`CXX_MODULE_SET` and
-:prop_tgt:`INTERFACE_CXX_MODULE_SETS`.
+Related properties:
+
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_CXX_MODULE_SETS`
+* :prop_tgt:`CXX_MODULE_SET_<NAME>`
+* :prop_tgt:`CXX_MODULE_SET`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``CXX_MODULES``

Help/prop_tgt/FILE_SETS_TYPE.rst

@@ -0,0 +1,25 @@
+FILE_SETS_<TYPE>
+----------------
+
+.. versionadded:: 4.5
+
+Read-only list of the target's ``PRIVATE`` and ``PUBLIC`` file sets of type
+``<TYPE>``.
+
+See Also
+^^^^^^^^
+
+Related properties:
+
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>` to list the target's ``INTERFACE`` file sets
+* :prop_tgt:`FILE_SET_TYPES` to list the target's file set types
+* :prop_tgt:`HEADER_SETS` to list the target's ``PRIVATE`` file sets of type
+  ``HEADER``
+* :prop_tgt:`SOURCE_SETS` to list the target's ``PRIVATE`` file sets of type
+  ``SOURCE``
+* :prop_tgt:`CXX_MODULE_SETS` to list the target's ``PRIVATE`` file sets of
+  type ``CXX_MODULES``
+
+Related commands:
+
+* :command:`target_sources` to define file sets

Help/prop_tgt/FILE_SET_TYPES.rst

@@ -0,0 +1,16 @@
+FILE_SET_TYPES
+--------------
+
+.. versionadded:: 4.5
+
+Read-only list of the target's file set types.
+
+See Also
+^^^^^^^^
+
+Related properties:
+
+* :prop_tgt:`FILE_SETS_<TYPE>` to list ``PRIVATE`` and ``PUBLIC`` file sets of
+  type ``<TYPE>``.
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>` to list ``INTERFACE`` and ``PUBLIC``
+  file sets of type ``<TYPE>``.

Help/prop_tgt/HEADER_SETS.rst

@@ -8,8 +8,17 @@ all file sets with the type ``HEADERS``). Files listed in these file sets are
 treated as source files for the purpose of IDE integration. The files also
 have their :prop_sf:`HEADER_FILE_ONLY` property set to ``TRUE``.
 
-Header sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``HEADERS``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`HEADER_SET_<NAME>`, :prop_tgt:`HEADER_SET` and
-:prop_tgt:`INTERFACE_HEADER_SETS`.
+Related properties:
+
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_HEADER_SETS`
+* :prop_tgt:`HEADER_SET_<NAME>`
+* :prop_tgt:`HEADER_SET`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``HEADERS``

Help/prop_tgt/INTERFACE_CXX_MODULE_SETS.rst

@@ -8,7 +8,15 @@ with the type ``CXX_MODULES``). Files listed in these C++ module sets can be
 installed with :command:`install(TARGETS)` and exported with
 :command:`install(EXPORT)` and :command:`export`.
 
-C++ module sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``CXX_MODULES``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`CXX_MODULE_SETS`.
+Related properties:
+
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`CXX_MODULE_SETS`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``CXX_MODULES``

Help/prop_tgt/INTERFACE_FILE_SETS_TYPE.rst

@@ -0,0 +1,25 @@
+INTERFACE_FILE_SETS_<TYPE>
+--------------------------
+
+.. versionadded:: 4.5
+
+Read-only list of the target's ``INTERFACE`` and ``PUBLIC`` file sets of type
+``<TYPE>``.
+
+See Also
+^^^^^^^^
+
+Related properties:
+
+* :prop_tgt:`FILE_SETS_<TYPE>` to list the target's ``PRIVATE`` file sets
+* :prop_tgt:`FILE_SET_TYPES` to list the target's file set types
+* :prop_tgt:`INTERFACE_HEADER_SETS` to list the target's ``INTERFACE`` file
+  sets of type ``HEADER``
+* :prop_tgt:`INTERFACE_SOURCE_SETS` to list the target's ``INTERFACE`` file
+  sets of type ``SOURCE``
+* :prop_tgt:`INTERFACE_CXX_MODULE_SETS` to list the target's ``INTERFACE`` file
+  sets of type ``CXX_MODULES``
+
+Related commands:
+
+* :command:`target_sources` to define file sets

Help/prop_tgt/INTERFACE_HEADER_SETS.rst

@@ -8,7 +8,15 @@ all file sets with the type ``HEADERS``). Files listed in these header sets
 can be installed with :command:`install(TARGETS)` and exported with
 :command:`install(EXPORT)` and :command:`export`.
 
-Header sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``HEADERS``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`HEADER_SETS`.
+Related properties:
+
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`HEADER_SETS`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``HEADERS``

Help/prop_tgt/INTERFACE_SOURCE_SETS.rst

@@ -8,7 +8,15 @@ all file sets with the type ``SOURCES``). Files listed in these source sets
 can be installed with :command:`install(TARGETS)` and exported with
 :command:`install(EXPORT)` and :command:`export`.
 
-Source sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``SOURCES``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`SOURCE_SETS`.
+Related properties:
+
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`SOURCE_SETS`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``SOURCES``

Help/prop_tgt/SOURCE_SETS.rst

@@ -7,8 +7,17 @@ Read-only list of the target's ``PRIVATE`` and ``PUBLIC`` source sets (i.e.
 all file sets with the type ``SOURCES``). Files listed in these file sets are
 treated as source files.
 
-Source sets may be defined using the :command:`target_sources` command
-``FILE_SET`` option with type ``SOURCES``.
+See Also
+^^^^^^^^
 
-See also :prop_tgt:`SOURCE_SET_<NAME>`, :prop_tgt:`SOURCE_SET` and
-:prop_tgt:`INTERFACE_SOURCE_SETS`.
+Related properties:
+
+* :prop_tgt:`FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>`
+* :prop_tgt:`INTERFACE_SOURCE_SETS`
+* :prop_tgt:`SOURCE_SET_<NAME>`
+* :prop_tgt:`SOURCE_SET`
+
+Related commands:
+
+* :command:`target_sources` to define file sets of type ``SOURCES``

Help/release/dev/target-FILE_SET-properties.rst

@@ -0,0 +1,6 @@
+target-FILE_SET-properties
+--------------------------
+
+* The :prop_tgt:`FILE_SET_TYPES`, :prop_tgt:`FILE_SETS_<TYPE>`, and
+  :prop_tgt:`INTERFACE_FILE_SETS_<TYPE>` target properties were added to get
+  information about file sets attached to the target.

Source/cmTarget.cxx

@@ -41,6 +41,7 @@
 #include "cmState.h"
 #include "cmStateDirectory.h"
 #include "cmStateSnapshot.h"
+#include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTargetPropertyComputer.h"
 #include "cmValue.h"
@@ -2114,6 +2115,7 @@ bool IsSettableProperty(cmMakefile* context, cmTarget* target,
   using ROC = ReadOnlyCondition;
   static std::unordered_map<std::string, ReadOnlyProperty> const readOnlyProps{
     { "EXPORT_NAME", { ROC::Imported } },
+    { "FILE_SET_TYPES", { ROC::All } },
     { "HEADER_SETS", { ROC::All } },
     { "IMPORTED_GLOBAL", { ROC::NonImported } },
     { "INTERFACE_HEADER_SETS", { ROC::All } },
@@ -2181,6 +2183,11 @@ void cmTarget::SetProperty(std::string const& prop, cmValue value)
     }
   }
 
+  if (cmHasPrefix(prop, "FILE_SETS_"_s) ||
+      cmHasPrefix(prop, "INTERFACE_FILE_SETS_"_s)) {
+    // these properties are always read-only
+    return;
+  }
   for (auto& fileSetType : this->impl->FileSetTypes) {
     if (fileSetType.second.WriteProperties(this, this->impl.get(), prop, value,
                                            FileSetType::Action::Set)) {
@@ -2773,6 +2780,32 @@ cmValue cmTarget::GetProperty(std::string const& prop) const
   }
 
   // Check fileset properties.
+  if (prop == "FILE_SET_TYPES"_s) {
+    static std::string fsTypes;
+    cmList types;
+    for (auto const& fileSetType : this->impl->FileSetTypes) {
+      if (!fileSetType.second.SelfEntries.Entries.empty() ||
+          !fileSetType.second.InterfaceEntries.Entries.empty()) {
+        types.push_back(fileSetType.first);
+      }
+    }
+    std::sort(types.begin(), types.end());
+    fsTypes = types.to_string();
+    return cmValue{ fsTypes };
+  }
+  if (cmHasPrefix(prop, "FILE_SETS_"_s)) {
+    static std::string fileSets;
+    std::string type = prop.substr(10);
+    fileSets = cmList::to_string(this->GetFileSetsEntries(type));
+    return cmValue{ fileSets };
+  }
+  if (cmHasPrefix(prop, "INTERFACE_FILE_SETS_"_s)) {
+    static std::string fileSets;
+    std::string type = prop.substr(20);
+    fileSets = cmList::to_string(this->GetInterfaceFileSetsEntries(type));
+    return cmValue{ fileSets };
+  }
+
   {
     for (auto const& fileSetType : this->impl->FileSetTypes) {
       auto value =

Tests/RunCMake/target_sources/FileSetProperties.cmake

@@ -21,10 +21,14 @@ assert_prop_eq(lib1 HEADER_SETS "")
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "")
 assert_prop_undef(lib1 INCLUDE_DIRECTORIES)
 assert_prop_undef(lib1 INTERFACE_INCLUDE_DIRECTORIES)
+assert_prop_eq(lib1 FILE_SET_TYPES "")
 
 target_sources(lib1 PUBLIC FILE_SET a TYPE HEADERS BASE_DIRS "." FILES h1.h h2.h)
 assert_prop_eq(lib1 HEADER_SETS "a")
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a")
+assert_prop_eq(lib1 FILE_SET_TYPES "HEADERS")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a")
 assert_prop_eq(lib1 HEADER_DIRS_a "${CMAKE_CURRENT_SOURCE_DIR}/.")
 assert_prop_eq(lib1 HEADER_SET_a "${CMAKE_CURRENT_SOURCE_DIR}/h1.h;${CMAKE_CURRENT_SOURCE_DIR}/h2.h")
 assert_prop_eq(lib1 INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/.>")
@@ -41,6 +45,9 @@ assert_prop_eq(lib1 INTERFACE_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CUR
 target_sources(lib1 PRIVATE FILE_SET b TYPE HEADERS BASE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}/dir" FILES dir/dir.h)
 assert_prop_eq(lib1 HEADER_SETS "a;b")
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a")
+assert_prop_eq(lib1 FILE_SET_TYPES "HEADERS")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a")
 assert_prop_eq(lib1 HEADER_DIRS_b "${CMAKE_CURRENT_SOURCE_DIR}/dir")
 assert_prop_eq(lib1 HEADER_SET_b "${CMAKE_CURRENT_SOURCE_DIR}/dir/dir.h")
 assert_prop_eq(lib1 INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/.>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/dir>")
@@ -49,6 +56,8 @@ assert_prop_eq(lib1 INTERFACE_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CUR
 target_sources(lib1 INTERFACE FILE_SET c TYPE HEADERS FILE_SET d TYPE HEADERS)
 assert_prop_eq(lib1 HEADER_SETS "a;b")
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a;c;d")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a;c;d")
 assert_prop_eq(lib1 HEADER_DIRS_c "${CMAKE_CURRENT_SOURCE_DIR}")
 assert_prop_eq(lib1 HEADER_SET_c "")
 assert_prop_eq(lib1 HEADER_DIRS_d "${CMAKE_CURRENT_SOURCE_DIR}")
@@ -58,6 +67,8 @@ assert_prop_eq(lib1 INTERFACE_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CUR
 
 target_sources(lib1 PUBLIC FILE_SET HEADERS BASE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}" FILES h4.h)
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a;c;d;HEADERS")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b;HEADERS")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a;c;d;HEADERS")
 assert_prop_eq(lib1 HEADER_DIRS "${CMAKE_CURRENT_SOURCE_DIR}")
 assert_prop_eq(lib1 HEADER_SET "${CMAKE_CURRENT_SOURCE_DIR}/h4.h")
 assert_prop_eq(lib1 HEADER_DIRS_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}")
@@ -73,3 +84,10 @@ assert_prop_eq(lib1 HEADER_DIRS_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}")
 assert_prop_eq(lib1 HEADER_SET_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}/h4.h;${CMAKE_CURRENT_SOURCE_DIR}/h5.h")
 assert_prop_eq(lib1 INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/.>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/dir>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>")
 assert_prop_eq(lib1 INTERFACE_INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/.>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>")
+
+target_sources(lib1 PUBLIC FILE_SET src1 TYPE SOURCES FILES lib1.c)
+assert_prop_eq(lib1 FILE_SET_TYPES "HEADERS;SOURCES")
+assert_prop_eq(lib1 FILE_SETS_HEADERS "a;b;HEADERS")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_HEADERS "a;c;d;HEADERS")
+assert_prop_eq(lib1 FILE_SETS_SOURCES "src1")
+assert_prop_eq(lib1 INTERFACE_FILE_SETS_SOURCES "src1")