Add generator expression $<ARGS>

Fixes: #28122

Help/manual/cmake-generator-expressions.7.rst

@@ -3634,8 +3634,31 @@ Multi-level Expression Evaluation
         echo $<TARGET_GENEX_EVAL:foo,$<TARGET_PROPERTY:foo,CUSTOM_KEYS>>
     )
 
+Support Expressions
+-------------------
+
+Conversions
+^^^^^^^^^^^
+
+.. genex:: $<ARGS:cmake-list>
+
+  .. versionadded:: 4.5
+
+  Transform a :ref:`semicolon-separated list <CMake Language Lists>` into a
+  comma-separated list as expected by many generator expressions.
+
+  .. code-block:: cmake
+
+    # check if the current config is a debug one
+
+    ## Converting a cmake list by hand does not give the expected result
+    $<CONFIG:$<LIST:JOIN,$<GLOBAL_PROPERTY:DEBUG_CONFIGURATIONS>,$<COMMA>>>
+
+    ## correct way to proceed
+    $<CONFIG:$<ARGS:$<GLOBAL_PROPERTY:DEBUG_CONFIGURATIONS>>>
+
 Escaped Characters
-------------------
+^^^^^^^^^^^^^^^^^^
 
 These expressions evaluate to specific string literals. Use them in place of
 the actual string literal where you need to prevent them from having their

Help/release/dev/GenEx-ARGS.rst

@@ -0,0 +1,6 @@
+GenEx-ARGS
+----------
+
+* CMake gains the :genex:`$<ARGS>` generator expression to convert a
+  :ref:`semicolon-separated list <CMake Language Lists>` into a comma-separated
+  list.

Source/cmGeneratorExpressionEvaluator.cxx

@@ -2,6 +2,11 @@
    file LICENSE.rst or https://cmake.org/licensing for details.  */
 #include "cmGeneratorExpressionEvaluator.h"
 
+#include <iterator>
+
+#include <cm/string_view>
+#include <cmext/string_view>
+
 #ifndef CMAKE_BOOTSTRAP
 #  include <cm3p/json/value.h>
 #endif
@@ -111,6 +116,33 @@ std::string GeneratorExpressionContent::Evaluate(
     return std::string();
   }
 
+  if (!parameters.empty()) {
+    cm::string_view ARGS_BEGIN = "<ARGS>"_s;
+    cm::string_view ARGS_END = "</ARGS>"_s;
+
+    std::vector<std::string> args;
+    // split any parameter with the prefix <ARGS>:
+    for (auto const& param : parameters) {
+      if (cmHasPrefix(param, ARGS_BEGIN) && cmHasSuffix(param, ARGS_END)) {
+        auto values = param.substr(ARGS_BEGIN.length(),
+                                   param.length() - ARGS_BEGIN.length() -
+                                     ARGS_END.length());
+        if (values.empty()) {
+          args.push_back(std::move(values));
+          continue;
+        }
+
+        std::vector<std::string> tokens =
+          cmTokenize(values, ',', cmTokenizerMode::New);
+        args.insert(args.end(), std::make_move_iterator(tokens.begin()),
+                    std::make_move_iterator(tokens.end()));
+      } else {
+        args.push_back(param);
+      }
+    }
+    parameters = std::move(args);
+  }
+
   {
 #ifndef CMAKE_BOOTSTRAP
     auto execProfilingRAII =

Source/cmGeneratorExpressionNode.cxx

@@ -360,6 +360,30 @@ static const struct BoolNode : public cmGeneratorExpressionNode
   }
 } boolNode;
 
+static const struct ArgsNode : public cmGeneratorExpressionNode
+{
+  ArgsNode() {} // NOLINT(modernize-use-equals-default)
+
+  int NumExpectedParameters() const override { return ZeroOrMoreParameters; }
+
+  std::string Evaluate(std::vector<std::string> const& parameters,
+                       cm::GenEx::Evaluation*,
+                       GeneratorExpressionContent const*,
+                       cmGeneratorExpressionDAGChecker*) const override
+  {
+    if (parameters.empty()) {
+      return std::string{};
+    }
+    if (parameters.size() == 1 && parameters[0].empty()) {
+      return parameters.front();
+    }
+
+    cmList args{ parameters.begin(), parameters.end(),
+                 cmList::ExpandElements::Yes, cmList::EmptyElements::Yes };
+    return cmStrCat("<ARGS>", args.join(","_s), "</ARGS>");
+  }
+} argsNode;
+
 static const struct IfNode : public cmGeneratorExpressionNode
 {
   IfNode() {} // NOLINT(modernize-use-equals-default)
@@ -6460,6 +6484,7 @@ cmGeneratorExpressionNode const* cmGeneratorExpressionNode::GetNode(
     { "AND", &andNode },
     { "OR", &orNode },
     { "NOT", &notNode },
+    { "ARGS", &argsNode },
     { "C_COMPILER_ID", &cCompilerIdNode },
     { "CXX_COMPILER_ID", &cxxCompilerIdNode },
     { "OBJC_COMPILER_ID", &objcCompilerIdNode },

Tests/RunCMake/CMakeLists.txt

@@ -573,6 +573,7 @@ add_RunCMake_test(GenEx-LINK_GROUP)
 add_RunCMake_test(GenEx-TARGET_FILE -DLINKER_SUPPORTS_PDB=${LINKER_SUPPORTS_PDB})
 add_RunCMake_test(GenEx-TARGET_IMPORT_FILE)
 add_RunCMake_test(GenEx-GENEX_EVAL)
+add_RunCMake_test(GenEx-ARGS)
 add_RunCMake_test(GenEx-GLOBAL_PROPERTY)
 add_RunCMake_test(GenEx-RULE_PROPERTY)
 add_RunCMake_test(GenEx-SOURCE_EXISTS)

Tests/RunCMake/GenEx-ARGS/CMakeLists.txt

@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 4.0...4.4)
+
+project(${RunCMake_TEST} NONE)
+
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/GenEx-ARGS/RunCMakeTest.cmake

@@ -0,0 +1,11 @@
+
+include(RunCMake)
+
+run_cmake(no-arguments)
+run_cmake(list-conversion)
+
+if(RunCMake_GENERATOR_IS_MULTI_CONFIG)
+  run_cmake_with_options(simple -DCMAKE_CONFIGURATION_TYPES=Debug)
+else()
+  run_cmake_with_options(simple -DCMAKE_BUILD_TYPE=Debug)
+endif()

Tests/RunCMake/GenEx-ARGS/list-conversion-check.cmake

@@ -0,0 +1,6 @@
+file(READ "${RunCMake_TEST_BINARY_DIR}/list-conversion-generated.txt" content)
+
+set(reference "<ARGS>AA,BB</ARGS>|<ARGS>CC,DD</ARGS>|<ARGS>EE,FF,GG</ARGS>")
+if(NOT content MATCHES "${reference}")
+  set(RunCMake_TEST_FAILED "actual content:\n [[${content}]]\nbut expected:\n [[${reference}]]")
+endif()

Tests/RunCMake/GenEx-ARGS/list-conversion.cmake

@@ -0,0 +1,6 @@
+
+set_property(GLOBAL PROPERTY COMMA_LIST "AA,BB")
+set_property(GLOBAL PROPERTY CMAKE_LIST "CC;DD")
+set_property(GLOBAL PROPERTY MIX_LIST "EE,FF;GG")
+
+file(GENERATE OUTPUT list-conversion-generated.txt CONTENT "$<ARGS:$<GLOBAL_PROPERTY:COMMA_LIST>>|$<ARGS:$<GLOBAL_PROPERTY:CMAKE_LIST>>|$<ARGS:$<GLOBAL_PROPERTY:MIX_LIST>>")

Tests/RunCMake/GenEx-ARGS/no-arguments-check.cmake

@@ -0,0 +1,5 @@
+file(READ "${RunCMake_TEST_BINARY_DIR}/no-arguments-generated.txt" content)
+
+if(NOT content MATCHES "><|><")
+  set(RunCMake_TEST_FAILED "actual content:\n [[${content}]]\nbut expected:\n [[><|><]]")
+endif()

Tests/RunCMake/GenEx-ARGS/no-arguments.cmake

@@ -0,0 +1,2 @@
+
+file(GENERATE OUTPUT no-arguments-generated.txt CONTENT ">$<ARGS><|>$<ARGS:><")

Tests/RunCMake/GenEx-ARGS/simple-check.cmake

@@ -0,0 +1,5 @@
+file(READ "${RunCMake_TEST_BINARY_DIR}/simple-generated.txt" content)
+
+if(NOT content MATCHES "1")
+  set(RunCMake_TEST_FAILED "actual content:\n [[${content}]]\nbut expected:\n [[1]]")
+endif()

Tests/RunCMake/GenEx-ARGS/simple.cmake

@@ -0,0 +1,3 @@
+
+set_property(GLOBAL PROPERTY DEBUG_CONGIFURATIONS Debug Other)
+file(GENERATE OUTPUT simple-generated.txt CONTENT "$<CONFIG:$<ARGS:$<GLOBAL_PROPERTY:DEBUG_CONGIFURATIONS>>>")