Xcode: Honor generator expressions in XCODE_EMBED_<type>

Evaluate the XCODE_EMBED_<type> target property through the generator
expression evaluator before building the copy-files phase.  Xcode shares
one copy-files build phase across all configurations, so the embedded set
cannot vary by configuration.  Reject any expression whose result depends
on the configuration, matching the existing per-source diagnostic.

Fixes #28082

Help/prop_tgt/XCODE_EMBED_type.rst

@@ -65,6 +65,14 @@ at least one of the following:
   directory and no other :command:`project` calls between themselves and that
   common :command:`project` call.
 
+.. versionadded:: 4.5
+
+  Contents of ``XCODE_EMBED_<type>`` may use
+  :manual:`generator expressions <cmake-generator-expressions(7)>`.
+  Xcode shares one copy-files build phase across all configurations, so the
+  embedded set cannot vary by configuration.  A generator expression whose
+  result depends on the configuration is rejected with an error.
+
 See also :prop_tgt:`XCODE_EMBED_<type>_PATH`,
 :prop_tgt:`XCODE_EMBED_<type>_REMOVE_HEADERS_ON_COPY` and
 :prop_tgt:`XCODE_EMBED_<type>_CODE_SIGN_ON_COPY`.

Help/release/dev/xcode-embed-genex.rst

@@ -0,0 +1,8 @@
+xcode-embed-genex
+-----------------
+
+* The :prop_tgt:`XCODE_EMBED_<type>` target property now supports
+  :manual:`generator expressions <cmake-generator-expressions(7)>`.
+  Because Xcode shares one copy-files build phase across all configurations,
+  an expression whose result depends on the configuration is rejected with
+  an error.

Source/cmGlobalXCodeGenerator.cxx

@@ -1037,6 +1037,14 @@ public:
   {
   }
 
+  XCodeGeneratorExpressionInterpreter(cmLocalGenerator* localGenerator,
+                                      cmGeneratorTarget* headTarget)
+    : cmGeneratorExpressionInterpreter(
+        localGenerator, "NO-PER-CONFIG-SUPPORT-IN-XCODE", headTarget)
+    , Target(headTarget)
+  {
+  }
+
   XCodeGeneratorExpressionInterpreter(
     XCodeGeneratorExpressionInterpreter const&) = delete;
   XCodeGeneratorExpressionInterpreter& operator=(
@@ -1055,13 +1063,23 @@ public:
       this->cmGeneratorExpressionInterpreter::Evaluate(expression, property);
     if (this->CompiledGeneratorExpression->GetHadContextSensitiveCondition()) {
       std::ostringstream e;
-      /* clang-format off */
-      e <<
-          "Xcode does not support per-config per-source " << property << ":\n"
-          "  " << expression << "\n"
-          "specified for source:\n"
-          "  " << this->SourceFile->ResolveFullPath() << '\n';
-      /* clang-format on */
+      if (this->SourceFile) {
+        /* clang-format off */
+        e <<
+            "Xcode does not support per-config per-source " << property << ":\n"
+            "  " << expression << "\n"
+            "specified for source:\n"
+            "  " << this->SourceFile->ResolveFullPath() << '\n';
+        /* clang-format on */
+      } else {
+        /* clang-format off */
+        e <<
+            "Xcode does not support per-config " << property << ":\n"
+            "  " << expression << "\n"
+            "specified for target:\n"
+            "  " << this->Target->GetName() << '\n';
+        /* clang-format on */
+      }
       this->LocalGenerator->IssueMessage(MessageType::FATAL_ERROR, e.str());
     }
 
@@ -1070,6 +1088,7 @@ public:
 
 private:
   cmSourceFile* SourceFile = nullptr;
+  cmGeneratorTarget* Target = nullptr;
 };
 
 cmXCodeObject* cmGlobalXCodeGenerator::CreateXCodeSourceFile(
@@ -4396,6 +4415,14 @@ void cmGlobalXCodeGenerator::AddEmbeddedObjects(
     return;
   }
 
+  // Xcode shares one copy-files build phase across all configurations, so the
+  // embedded set cannot vary by config. Evaluate the property and reject any
+  // generator expression whose result depends on the configuration.
+  XCodeGeneratorExpressionInterpreter genexInterpreter(gt->GetLocalGenerator(),
+                                                       gt);
+  std::string const& evaluatedFiles =
+    genexInterpreter.Evaluate(*files, embedPropertyName);
+
   // Create an "Embedded Frameworks" build phase
   auto* copyFilesBuildPhase =
     this->CreateObject(cmXCodeObject::PBXCopyFilesBuildPhase);
@@ -4418,7 +4445,7 @@ void cmGlobalXCodeGenerator::AddEmbeddedObjects(
                                     this->CreateString("0"));
   cmXCodeObject* buildFiles = this->CreateObject(cmXCodeObject::OBJECT_LIST);
   // Collect all embedded frameworks and dylibs and add them to build phase
-  cmList relFiles{ *files };
+  cmList relFiles{ evaluatedFiles };
   for (std::string const& relFile : relFiles) {
     cmXCodeObject* buildFile{ nullptr };
     std::string filePath = relFile;

Tests/RunCMake/XcodeProject-Embed/EmbedFrameworksGenex-check.cmake

@@ -0,0 +1,14 @@
+# The generator expression must resolve to the "embedded" framework target so
+# that an "Embed Frameworks" copy-files phase is created. Were the expression
+# left unevaluated, target lookup would fail and no such phase would exist.
+execute_process(
+  COMMAND grep -c "Embed Frameworks"
+                  ${RunCMake_TEST_BINARY_DIR}/${test}.xcodeproj/project.pbxproj
+  OUTPUT_VARIABLE actualCount
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+if(NOT actualCount MATCHES "^[0-9]+$" OR actualCount EQUAL 0)
+  set(RunCMake_TEST_FAILED
+    "no Embed Frameworks phase in project; generator expression was not honored")
+endif()

Tests/RunCMake/XcodeProject-Embed/EmbedFrameworksGenex.cmake

@@ -0,0 +1,9 @@
+# A generator expression whose result does not depend on the configuration is
+# honored. Here it resolves to the name of a framework target to embed.
+add_library(embedded SHARED func.m)
+set_target_properties(embedded PROPERTIES FRAMEWORK TRUE)
+
+add_executable(app MACOSX_BUNDLE main.m)
+set_target_properties(app PROPERTIES
+  XCODE_EMBED_FRAMEWORKS "$<1:embedded>"
+)

Tests/RunCMake/XcodeProject-Embed/EmbedFrameworksPerConfig-result.txt

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

Tests/RunCMake/XcodeProject-Embed/EmbedFrameworksPerConfig-stderr.txt

@@ -0,0 +1,10 @@
+^CMake Error in CMakeLists\.txt:
+  Xcode does not support per-config XCODE_EMBED_FRAMEWORKS:
+
+    \$<\$<CONFIG:Debug>:foo\.framework>
+
+  specified for target:
+
+    app
++
+CMake Generate step failed\.  Build files cannot be regenerated correctly\.$

Tests/RunCMake/XcodeProject-Embed/EmbedFrameworksPerConfig.cmake

@@ -0,0 +1,5 @@
+add_executable(app MACOSX_BUNDLE main.m)
+
+set_target_properties(app PROPERTIES
+  XCODE_EMBED_FRAMEWORKS "$<$<CONFIG:Debug>:foo.framework>"
+)

Tests/RunCMake/XcodeProject-Embed/RunCMakeTest.cmake

@@ -21,6 +21,13 @@ function(ExternalDependencies)
 endfunction()
 ExternalDependencies()
 
+# A generator expression that does not depend on the configuration is honored.
+run_cmake(EmbedFrameworksGenex)
+
+# A generator expression whose result depends on the configuration cannot be
+# honored, because Xcode shares one copy-files build phase across all configs.
+run_cmake(EmbedFrameworksPerConfig)
+
 function(TestFlagsOn testName dependencyName)
   set(RunCMake_TEST_NO_CLEAN 1)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${testName}-${dependencyName}-build)