Merge branch 'backport-project-vars' into project-vars

Help/command/project.rst

@@ -44,6 +44,12 @@ Projects should not rely on ``<PROJECT-NAME>_SOURCE_DIR`` or
 ``<PROJECT-NAME>_BINARY_DIR`` holding a particular value outside of the scope
 of the call to ``project()`` or one of its child scopes.
 
+.. versionchanged:: 3.30.4
+  If the variables ``<PROJECT-NAME>_SOURCE_DIR``,
+  ``<PROJECT-NAME>_BINARY_DIR``, or ``<PROJECT-NAME>_IS_TOP_LEVEL`` are
+  already set as non-cache variables when ``project(<PROJECT-NAME> ...)``
+  is called, the ``project()`` command will overwrite the previous values.
+
 Options
 ^^^^^^^
 

Source/cmProjectCommand.cxx

@@ -8,6 +8,8 @@
 #include <limits>
 #include <utility>
 
+#include <cmext/string_view>
+
 #include "cmsys/RegularExpression.hxx"
 
 #include "cmExecutionStatus.h"
@@ -56,17 +58,21 @@ bool cmProjectCommand(std::vector<std::string> const& args,
 
   mf.SetProjectName(projectName);
 
-  mf.AddCacheDefinition(projectName + "_BINARY_DIR",
-                        mf.GetCurrentBinaryDirectory(),
+  std::string varName = cmStrCat(projectName, "_BINARY_DIR"_s);
+  bool nonCacheVarAlreadySet = mf.IsDefinitionSet(varName);
+  mf.AddCacheDefinition(varName, mf.GetCurrentBinaryDirectory(),
                         "Value Computed by CMake", cmStateEnums::STATIC);
-  mf.AddDefinition(projectName + "_BINARY_DIR",
-                   mf.GetCurrentBinaryDirectory());
+  if (nonCacheVarAlreadySet) {
+    mf.AddDefinition(varName, mf.GetCurrentBinaryDirectory());
+  }
 
-  mf.AddCacheDefinition(projectName + "_SOURCE_DIR",
-                        mf.GetCurrentSourceDirectory(),
+  varName = cmStrCat(projectName, "_SOURCE_DIR"_s);
+  nonCacheVarAlreadySet = mf.IsDefinitionSet(varName);
+  mf.AddCacheDefinition(varName, mf.GetCurrentSourceDirectory(),
                         "Value Computed by CMake", cmStateEnums::STATIC);
-  mf.AddDefinition(projectName + "_SOURCE_DIR",
-                   mf.GetCurrentSourceDirectory());
+  if (nonCacheVarAlreadySet) {
+    mf.AddDefinition(varName, mf.GetCurrentSourceDirectory());
+  }
 
   mf.AddDefinition("PROJECT_BINARY_DIR", mf.GetCurrentBinaryDirectory());
   mf.AddDefinition("PROJECT_SOURCE_DIR", mf.GetCurrentSourceDirectory());
@@ -74,11 +80,14 @@ bool cmProjectCommand(std::vector<std::string> const& args,
   mf.AddDefinition("PROJECT_NAME", projectName);
 
   mf.AddDefinitionBool("PROJECT_IS_TOP_LEVEL", mf.IsRootMakefile());
-  mf.AddCacheDefinition(projectName + "_IS_TOP_LEVEL",
-                        mf.IsRootMakefile() ? "ON" : "OFF",
+
+  varName = cmStrCat(projectName, "_IS_TOP_LEVEL"_s);
+  nonCacheVarAlreadySet = mf.IsDefinitionSet(varName);
+  mf.AddCacheDefinition(varName, mf.IsRootMakefile() ? "ON" : "OFF",
                         "Value Computed by CMake", cmStateEnums::STATIC);
-  mf.AddDefinition(projectName + "_IS_TOP_LEVEL",
-                   mf.IsRootMakefile() ? "ON" : "OFF");
+  if (nonCacheVarAlreadySet) {
+    mf.AddDefinition(varName, mf.IsRootMakefile() ? "ON" : "OFF");
+  }
 
   // Set the CMAKE_PROJECT_NAME variable to be the highest-level
   // project name in the tree. If there are two project commands

Tests/RunCMake/project/RunCMakeTest.cmake

@@ -45,6 +45,7 @@ run_cmake(ProjectIsTopLevel)
 run_cmake(ProjectIsTopLevelMultiple)
 run_cmake(ProjectIsTopLevelSubdirectory)
 run_cmake(ProjectTwice)
+run_cmake(SameProjectVarsSubdir)
 run_cmake(VersionAndLanguagesEmpty)
 run_cmake(VersionEmpty)
 run_cmake(VersionInvalid)

Tests/RunCMake/project/SameProjectVarsSubdir-stdout.txt

@@ -0,0 +1,9 @@
+(-- )?  SameProjectVarsSubdir_SOURCE_DIR = [^
+]+/subdir1
+  SameProjectVarsSubdir_BINARY_DIR = [^
+]+/subdir1
+  SameProjectVarsSubdir_IS_TOP_LEVEL = OFF
+(-- )?  sub2proj_SOURCE_DIR = [^
+]+/subdir2
+  sub2proj_BINARY_DIR = [^
+]+/subdir2

Tests/RunCMake/project/SameProjectVarsSubdir.cmake

@@ -0,0 +1,17 @@
+add_subdirectory(subdir1)
+
+# Simulate a situation that FetchContent_MakeAvailable() used to be able to
+# create, but that should no longer be possible. If depname_SOURCE_DIR and
+# depname_BINARY_DIR variables are defined as non-cache variables before the
+# project(depname) call, those non-cache variables used to prevent project()
+# from setting those variables itself due to CMP0126 (if set to NEW). This only
+# showed up if the project(depname) call was not in the dependency's top level
+# CMakeLists.txt file, but rather in a subdirectory (googletest is one example
+# that used to do this). Since CMake 3.30.3, the dependency's project() call
+# should set non-cache variables that will make the variable values visible
+# and avoid any masking from variables set before the project() call. We want
+# to verify this 3.30.3+ behavior here and in subdir2.
+set(sub2proj_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+set(sub2proj_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+
+add_subdirectory(subdir2)

Tests/RunCMake/project/subdir1/CMakeLists.txt

@@ -0,0 +1 @@
+project(${RunCMake_TEST} LANGUAGES NONE)

Tests/RunCMake/project/subdir2/CMakeLists.txt

@@ -0,0 +1,12 @@
+message(STATUS
+  "  ${RunCMake_TEST}_SOURCE_DIR = ${${RunCMake_TEST}_SOURCE_DIR}\n"
+  "  ${RunCMake_TEST}_BINARY_DIR = ${${RunCMake_TEST}_BINARY_DIR}\n"
+  "  ${RunCMake_TEST}_IS_TOP_LEVEL = ${${RunCMake_TEST}_IS_TOP_LEVEL}"
+)
+
+project(sub2proj LANGUAGES NONE)
+
+message(STATUS
+  "  sub2proj_SOURCE_DIR = ${sub2proj_SOURCE_DIR}\n"
+  "  sub2proj_BINARY_DIR = ${sub2proj_BINARY_DIR}"
+)