Genex: Add $<BUILD_LOCAL_INTERFACE:...> genex

Fixes: #23209

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

@@ -1704,6 +1704,13 @@ Export And Install Expressions
   when the target is used by another target in the same buildsystem. Expands to
   the empty string otherwise.
 
+.. genex:: $<BUILD_LOCAL_INTERFACE:...>
+
+  .. versionadded:: 3.26
+
+  Content of ``...`` when the target is used by another target in the same
+  buildsystem. Expands to the empty string otherwise.
+
 .. genex:: $<INSTALL_PREFIX>
 
   Content of the install prefix when the target is exported via

Help/release/dev/build-local-interface-genex.rst

@@ -0,0 +1,5 @@
+build-local-interface-genex
+---------------------------
+
+* The :genex:`BUILD_LOCAL_INTERFACE` generator expression was added to
+  prevent usage requirements from being exported to dependent projects.

Source/cmGeneratorExpression.cxx

@@ -227,8 +227,10 @@ static std::string stripExportInterface(
   while (true) {
     std::string::size_type bPos = input.find("$<BUILD_INTERFACE:", lastPos);
     std::string::size_type iPos = input.find("$<INSTALL_INTERFACE:", lastPos);
+    std::string::size_type lPos =
+      input.find("$<BUILD_LOCAL_INTERFACE:", lastPos);
 
-    pos = std::min({ bPos, iPos });
+    pos = std::min({ bPos, iPos, lPos });
     if (pos == std::string::npos) {
       break;
     }
@@ -238,6 +240,7 @@ static std::string stripExportInterface(
     {
       BuildInterface,
       InstallInterface,
+      BuildLocalInterface,
     } foundGenex = FoundGenex::BuildInterface;
     if (pos == bPos) {
       foundGenex = FoundGenex::BuildInterface;
@@ -245,6 +248,9 @@ static std::string stripExportInterface(
     } else if (pos == iPos) {
       foundGenex = FoundGenex::InstallInterface;
       pos += cmStrLen("$<INSTALL_INTERFACE:");
+    } else if (pos == lPos) {
+      foundGenex = FoundGenex::BuildLocalInterface;
+      pos += cmStrLen("$<BUILD_LOCAL_INTERFACE:");
     } else {
       assert(false && "Invalid position found");
     }
@@ -287,6 +293,9 @@ static std::string stripExportInterface(
         case FoundGenex::InstallInterface:
           result = cmStrCat(result, "$<INSTALL_INTERFACE:", remaining);
           break;
+        case FoundGenex::BuildLocalInterface:
+          result = cmStrCat(result, "$<BUILD_LOCAL_INTERFACE:", remaining);
+          break;
       }
     }
     pos += traversed;

Source/cmGeneratorExpressionNode.cxx

@@ -114,6 +114,8 @@ static const struct OneNode buildInterfaceNode;
 
 static const struct ZeroNode installInterfaceNode;
 
+static const struct OneNode buildLocalInterfaceNode;
+
 struct BooleanOpNode : public cmGeneratorExpressionNode
 {
   BooleanOpNode(const char* op_, const char* successVal_,
@@ -3320,6 +3322,7 @@ const cmGeneratorExpressionNode* cmGeneratorExpressionNode::GetNode(
     { "GENEX_EVAL", &genexEvalNode },
     { "BUILD_INTERFACE", &buildInterfaceNode },
     { "INSTALL_INTERFACE", &installInterfaceNode },
+    { "BUILD_LOCAL_INTERFACE", &buildLocalInterfaceNode },
     { "INSTALL_PREFIX", &installPrefixNode },
     { "JOIN", &joinNode },
     { "LINK_ONLY", &linkOnlyNode },

Tests/RunCMake/ExportImport/BuildInstallInterfaceGenex-export.cmake

@@ -0,0 +1,14 @@
+enable_language(C)
+
+add_library(mainlib STATIC foo.c)
+target_compile_definitions(mainlib INTERFACE
+  $<BUILD_LOCAL_INTERFACE:BUILD_LOCAL_INTERFACE>
+  $<BUILD_INTERFACE:BUILD_INTERFACE>
+  $<INSTALL_INTERFACE:INSTALL_INTERFACE>
+  )
+add_library(locallib STATIC locallib.c)
+target_link_libraries(locallib PRIVATE mainlib)
+
+install(TARGETS mainlib EXPORT export)
+install(EXPORT export DESTINATION lib/cmake/install FILE install-config.cmake NAMESPACE install::)
+export(EXPORT export FILE build-config.cmake NAMESPACE build::)

Tests/RunCMake/ExportImport/BuildInstallInterfaceGenex-import.cmake

@@ -0,0 +1,9 @@
+enable_language(C)
+
+find_package(build REQUIRED)
+find_package(install REQUIRED)
+
+add_library(buildlib STATIC buildlib.c)
+target_link_libraries(buildlib PRIVATE build::mainlib)
+add_library(installlib STATIC installlib.c)
+target_link_libraries(installlib PRIVATE install::mainlib)

Tests/RunCMake/ExportImport/RunCMakeTest.cmake

@@ -22,3 +22,28 @@ function(run_ExportImport_test case)
 endfunction()
 
 run_ExportImport_test(SharedDep)
+
+function(run_ExportImportBuildInstall_test case)
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${case}-export-build)
+  set(CMAKE_INSTALL_PREFIX ${RunCMake_TEST_BINARY_DIR}/root)
+  if (NOT RunCMake_GENERATOR_IS_MULTI_CONFIG)
+    set(RunCMake_TEST_OPTIONS -DCMAKE_BUILD_TYPE=Debug)
+  endif()
+  run_cmake(${case}-export)
+  unset(RunCMake_TEST_OPTIONS)
+  set(RunCMake_TEST_NO_CLEAN 1)
+  run_cmake_command(${case}-export-build ${CMAKE_COMMAND} --build . --config Debug)
+  run_cmake_command(${case}-export-install ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX} -DBUILD_TYPE=Debug -P cmake_install.cmake)
+  unset(RunCMake_TEST_NO_CLEAN)
+
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${case}-import-build)
+  run_cmake_with_options(${case}-import
+    -Dbuild_DIR=${RunCMake_BINARY_DIR}/${case}-export-build
+    -Dinstall_DIR=${CMAKE_INSTALL_PREFIX}/lib/cmake/install
+    )
+  set(RunCMake_TEST_NO_CLEAN 1)
+  run_cmake_command(${case}-import-build ${CMAKE_COMMAND} --build . --config Debug)
+  unset(RunCMake_TEST_NO_CLEAN)
+endfunction()
+
+run_ExportImportBuildInstall_test(BuildInstallInterfaceGenex)

Tests/RunCMake/ExportImport/buildlib.c

@@ -0,0 +1,8 @@
+#if !(!defined(BUILD_LOCAL_INTERFACE) && defined(BUILD_INTERFACE) &&          \
+      !defined(INSTALL_INTERFACE))
+#  error "Incorrect compile definitions"
+#endif
+
+void buildlib(void)
+{
+}

Tests/RunCMake/ExportImport/installlib.c

@@ -0,0 +1,8 @@
+#if !(!defined(BUILD_LOCAL_INTERFACE) && !defined(BUILD_INTERFACE) &&         \
+      defined(INSTALL_INTERFACE))
+#  error "Incorrect compile definitions"
+#endif
+
+void installlib(void)
+{
+}

Tests/RunCMake/ExportImport/locallib.c

@@ -0,0 +1,8 @@
+#if !(defined(BUILD_LOCAL_INTERFACE) && defined(BUILD_INTERFACE) &&           \
+      !defined(INSTALL_INTERFACE))
+#  error "Incorrect compile definitions"
+#endif
+
+void locallib(void)
+{
+}