FILE_SET: enforce uniqueness of files

A file should be unique for a target if specified as part of a file set.

Issue: #27035

Help/command/target_sources.rst

@@ -77,7 +77,13 @@ File Sets
 Adds a file set to a target, or adds files to an existing file set. Targets
 have zero or more named file sets. Each file set has a name, a type, a scope of
 ``INTERFACE``, ``PUBLIC``, or ``PRIVATE``, one or more base directories, and
-files within those directories. The acceptable types include:
+files within those directories.
+
+.. versionchanged:: 4.4
+  A file may only belong to at most one file set in a target. See policy
+  :policy:`CMP0211`.
+
+ The acceptable types include:
 
 ``HEADERS``
 

Help/manual/cmake-policies.7.rst

@@ -94,6 +94,14 @@ Supported Policies
 
 The following policies are supported.
 
+Policies Introduced by CMake 4.4
+--------------------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   CMP0211: A file may belong to at most one file set in a target. </policy/CMP0211>
+
 Policies Introduced by CMake 4.3
 --------------------------------
 

Help/policy/CMP0211.rst

@@ -0,0 +1,22 @@
+CMP0211
+-------
+
+.. versionadded:: 4.4
+
+A file may belong to at most one :ref:`file set <file sets>` in a target.
+
+In CMake 4.3 and below, it was possible to specify the same file
+in multiple file sets in a target.  In CMake 4.4 and above, a file
+may belong to at most one file set in a target.  This policy provides
+compatibility for projects that have not been updated accordingly.
+
+The ``OLD`` behavior for this policy is to accept the same file in
+multiple file sets in a target.  The ``NEW`` behavior for this policy
+is to accept a given file in at most one file set in a target.
+
+.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 4.4
+.. |WARNS_OR_DOES_NOT_WARN| replace::
+    warns when a file is part of multiple file sets in a target
+.. include:: include/STANDARD_ADVICE.rst
+
+.. include:: include/DEPRECATED.rst

Help/release/dev/FILE_SET-enforce-files-unicity.rst

@@ -0,0 +1,5 @@
+FILE_SET-enforce-files-unicity
+------------------------------
+
+* A file may belong to at most one :ref:`file set <file sets>` in a target.
+  See policy :policy:`CMP0211`.

Source/cmDyndepCollation.cxx

@@ -119,24 +119,11 @@ TdiSourceInfo CollationInformationSources(cmGeneratorTarget const* gt,
       }
     }
 
-    // Detect duplicate sources.
-    std::set<std::string> visited_sources;
-
     for (auto const& files_per_dir : files_per_dirs.first) {
       for (auto const& file : files_per_dir.second) {
         auto const full_file = cmSystemTools::CollapseFullPath(file);
         auto lookup = sf_map.find(full_file);
         if (lookup == sf_map.end()) {
-          if (visited_sources.count(full_file)) {
-            // Duplicate source; raise an author warning.
-            gt->Makefile->IssueMessage(
-              MessageType::AUTHOR_WARNING,
-              cmStrCat("Target \"", tgt->GetName(), "\" has source file\n  ",
-                       file, "\nin a \"FILE_SET TYPE ",
-                       cm::FileSetMetadata::CXX_MODULES,
-                       "\" multiple times."));
-            continue;
-          }
           gt->Makefile->IssueMessage(MessageType::FATAL_ERROR,
                                      cmStrCat("Target \"", tgt->GetName(),
                                               "\" has source file\n  ", file,
@@ -146,7 +133,6 @@ TdiSourceInfo CollationInformationSources(cmGeneratorTarget const* gt,
                                               "scheduled for compilation."));
           continue;
         }
-        visited_sources.insert(full_file);
 
         auto const* sf = lookup->second.first;
         CompileType const ct = lookup->second.second;

Source/cmGeneratorFileSet.cxx

@@ -6,6 +6,7 @@
 #include <map>
 #include <sstream>
 #include <unordered_map>
+#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -144,14 +145,19 @@ std::vector<BT<std::string>> const& cmGeneratorFileSet::GetFileEntries() const
 std::vector<std::unique_ptr<cmCompiledGeneratorExpression>> const&
 cmGeneratorFileSet::CompileFileEntries() const
 {
+  std::unordered_set<std::string> uniqueSrcs;
+
   if (this->CompiledFileEntries.empty() &&
       !this->FileSet->GetFileEntries().empty()) {
     for (auto const& entry : this->FileSet->GetFileEntries()) {
       for (auto const& ex : cmList{ entry.Value }) {
-        cmGeneratorExpression ge(
-          *this->FileSet->GetMakefile()->GetCMakeInstance(), entry.Backtrace);
-        auto cge = ge.Parse(ex);
-        this->CompiledFileEntries.push_back(std::move(cge));
+        if (uniqueSrcs.insert(ex).second) {
+          cmGeneratorExpression ge(
+            *this->FileSet->GetMakefile()->GetCMakeInstance(),
+            entry.Backtrace);
+          auto cge = ge.Parse(ex);
+          this->CompiledFileEntries.push_back(std::move(cge));
+        }
       }
     }
   }

Source/cmGeneratorTarget_Sources.cxx

@@ -4,6 +4,8 @@
 #include "cmGeneratorTarget.h"
 /* clang-format on */
 
+#include "cmConfigure.h"
+
 #include <cstddef>
 #include <functional>
 #include <map>
@@ -34,6 +36,7 @@
 #include "cmLocalGenerator.h"
 #include "cmMakefile.h"
 #include "cmMessageType.h"
+#include "cmPolicies.h"
 #include "cmSourceFile.h"
 #include "cmSourceFileLocation.h"
 #include "cmSourceGroup.h"
@@ -93,7 +96,7 @@ void AddFileSetEntries(cmGeneratorTarget const* headTarget,
     EvaluateTargetPropertyEntries(headTarget, context, dagChecker, sources);
 }
 
-bool processSources(cmGeneratorTarget const* tgt,
+bool processSources(cmGeneratorTarget const* tgt, std::string const& config,
                     EvaluatedTargetPropertyEntries& entries,
                     std::vector<BT<std::string>>& srcs,
                     std::unordered_set<std::string>& uniqueSrcs,
@@ -155,6 +158,28 @@ bool processSources(cmGeneratorTarget const* tgt,
         if (debugSources) {
           usedSources += cmStrCat(" * ", src, '\n');
         }
+      } else {
+        if (auto const* fileSet =
+              tgt->GetGeneratorFileSets()->GetFileSetForSource(config, src)) {
+          switch (tgt->GetPolicyStatusCMP0211()) {
+            case cmPolicies::WARN:
+              tgt->GetLocalGenerator()->IssueMessage(
+                MessageType::AUTHOR_WARNING,
+                cmStrCat(cmPolicies::GetPolicyWarning(cmPolicies::CMP0211),
+                         "\nIn target \"", tgt->GetName(), "\" the file\n  ",
+                         src, "\nalready belongs to file set \"",
+                         fileSet->GetName(), "\"."));
+              CM_FALLTHROUGH;
+            case cmPolicies::OLD:
+              break;
+            default:
+              tgt->GetLocalGenerator()->IssueMessage(
+                MessageType::FATAL_ERROR,
+                cmStrCat("In target \"", tgt->GetName(), "\" the file\n  ",
+                         src, "\nalready belongs to file set \"",
+                         fileSet->GetName(), "\"."));
+          }
+        }
       }
     }
     if (!usedSources.empty()) {
@@ -193,23 +218,24 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetSourceFilePaths(
 
   std::unordered_set<std::string> uniqueSrcs;
   bool contextDependentDirectSources =
-    processSources(this, entries, files, uniqueSrcs, debugSources);
+    processSources(this, config, entries, files, uniqueSrcs, debugSources);
 
   // Collect INTERFACE_SOURCES of all direct link-dependencies.
   EvaluatedTargetPropertyEntries linkInterfaceSourcesEntries;
   AddInterfaceEntries(this, "INTERFACE_SOURCES", context, &dagChecker,
                       linkInterfaceSourcesEntries, IncludeRuntimeInterface::No,
                       UseTo::Compile);
-  bool contextDependentInterfaceSources = processSources(
-    this, linkInterfaceSourcesEntries, files, uniqueSrcs, debugSources);
+  bool contextDependentInterfaceSources =
+    processSources(this, config, linkInterfaceSourcesEntries, files,
+                   uniqueSrcs, debugSources);
 
   // Collect TARGET_OBJECTS of direct object link-dependencies.
   bool contextDependentObjects = false;
   if (this->GetType() != cmStateEnums::OBJECT_LIBRARY) {
     EvaluatedTargetPropertyEntries linkObjectsEntries;
     AddObjectEntries(this, context, &dagChecker, linkObjectsEntries);
-    contextDependentObjects = processSources(this, linkObjectsEntries, files,
-                                             uniqueSrcs, debugSources);
+    contextDependentObjects = processSources(this, config, linkObjectsEntries,
+                                             files, uniqueSrcs, debugSources);
     // Note that for imported targets or multi-config generators supporting
     // cross-config builds the paths to the object files must be per-config,
     // so contextDependentObjects will be true here even if object libraries
@@ -243,8 +269,8 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetSourceFilePaths(
 #endif
   };
   bool contextDependentFileSets =
-    processSources(this, fileSetEntries, files, uniqueSrcs, debugSources,
-                   processFileSetEntry);
+    processSources(this, config, fileSetEntries, files, uniqueSrcs,
+                   debugSources, processFileSetEntry);
 
   // Determine if sources are context-dependent or not.
   if (!contextDependentDirectSources && !contextDependentInterfaceSources &&

Source/cmPolicies.h

@@ -629,7 +629,10 @@ class cmMakefile;
          4, 3, 0, WARN)                                                       \
   SELECT(POLICY, CMP0210,                                                     \
          "CMAKE_<LANG>_LINK_FLAGS adds link flags to all target types.", 4,   \
-         3, 0, WARN)
+         3, 0, WARN)                                                          \
+  SELECT(POLICY, CMP0211,                                                     \
+         "A file may belong to at most one file set in a target.", 4, 4, 0,   \
+         WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \
@@ -684,7 +687,8 @@ class cmMakefile;
   F(CMP0203)                                                                  \
   F(CMP0204)                                                                  \
   F(CMP0209)                                                                  \
-  F(CMP0210)
+  F(CMP0210)                                                                  \
+  F(CMP0211)
 
 #define CM_FOR_EACH_CUSTOM_COMMAND_POLICY(F)                                  \
   F(CMP0116)                                                                  \

Tests/RunCMake/CXXModulesCompile/duplicate-sources-stderr.txt

@@ -1,8 +0,0 @@
-CMake Warning \(dev\) in CMakeLists\.txt:
-  Target "duplicate_sources" has source file
-
-    [^
-]*/Tests/RunCMake/CXXModulesCompile/duplicate-sources/duplicate\.cxx
-
-  in a "FILE_SET TYPE CXX_MODULES" multiple times\.
-This warning is for project developers\.  Use -Wno-dev to suppress it\.

Tests/RunCMake/FileSetProperties/SOURCES.cmake

@@ -40,11 +40,11 @@ if(NOT srcs MATCHES "[^;]*bar.h;[^;]*foo.h$")
 endif()
 
 
-target_sources(foo PRIVATE FILE_SET foo TYPE HEADERS FILES foo.h)
+target_sources(foo PRIVATE FILE_SET foo TYPE HEADERS FILES h1.h)
 
 get_property(srcs FILE_SET foo TARGET foo PROPERTY SOURCES)
-if(NOT srcs MATCHES ".*/foo.h$")
-  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'foo.h'")
+if(NOT srcs MATCHES ".*/h1.h$")
+  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'h1.h'")
 endif()
 get_property(srcs FILE_SET foo TARGET foo PROPERTY INTERFACE_SOURCES)
 if(srcs)
@@ -52,11 +52,11 @@ if(srcs)
 endif()
 
 
-set_property(FILE_SET foo TARGET foo PROPERTY SOURCES bar.h)
+set_property(FILE_SET foo TARGET foo PROPERTY SOURCES h2.h)
 
 get_property(srcs FILE_SET foo TARGET foo PROPERTY SOURCES)
-if(NOT srcs MATCHES "[^;]*bar.h$")
-  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'bar.h'")
+if(NOT srcs MATCHES "[^;]*h2.h$")
+  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'h2.h'")
 endif()
 get_property(srcs FILE_SET foo TARGET foo PROPERTY INTERFACE_SOURCES)
 if(srcs)
@@ -64,11 +64,11 @@ if(srcs)
 endif()
 
 
-set_property(FILE_SET foo TARGET foo PROPERTY INTERFACE_SOURCES foo.h)
+set_property(FILE_SET foo TARGET foo PROPERTY INTERFACE_SOURCES h2.h)
 
 get_property(srcs FILE_SET foo TARGET foo PROPERTY SOURCES)
-if(NOT srcs MATCHES "[^;]*bar.h$")
-  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'bar.h'")
+if(NOT srcs MATCHES "[^;]*h2.h$")
+  message(SEND_ERROR "wrong sources: '${srcs}' instead of 'h2.h'")
 endif()
 get_property(srcs FILE_SET foo TARGET foo PROPERTY INTERFACE_SOURCES)
 if(srcs)

Tests/RunCMake/TargetPolicies/PolicyList-stderr.txt

@@ -54,6 +54,7 @@
    \* CMP0204
    \* CMP0209
    \* CMP0210
+   \* CMP0211
 
 Call Stack \(most recent call first\):
   CMakeLists\.txt:3 \(include\)

Tests/RunCMake/target_sources/CMP0211-Common.cmake

@@ -0,0 +1,9 @@
+
+enable_language(C)
+
+add_library(foo1 STATIC lib1.c)
+target_sources(foo1 PRIVATE FILE_SET h1 TYPE HEADERS FILES h1.h)
+target_sources(foo1 PRIVATE FILE_SET h2 TYPE HEADERS FILES h1.h)
+
+add_library(foo2 STATIC lib1.c h1.h)
+target_sources(foo2 PRIVATE FILE_SET h1 TYPE HEADERS FILES h1.h)

Tests/RunCMake/target_sources/CMP0211-NEW-result.txt

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

Tests/RunCMake/target_sources/CMP0211-NEW-stderr.txt

@@ -0,0 +1,14 @@
+CMake Error in CMakeLists\.txt:
+  In target "foo1" the file
+
+    .+/Tests/RunCMake/target_sources/h1\.h
+
+  already belongs to file set "h2"\.
+
+
+CMake Error in CMakeLists\.txt:
+  In target "foo2" the file
+
+    .+/Tests/RunCMake/target_sources/h1\.h
+
+  already belongs to file set "h1"\.

Tests/RunCMake/target_sources/CMP0211-NEW.cmake

@@ -0,0 +1,4 @@
+
+cmake_policy(SET CMP0211 NEW)
+
+include(CMP0211-Common.cmake)

Tests/RunCMake/target_sources/CMP0211-OLD.cmake

@@ -0,0 +1,4 @@
+
+cmake_policy(SET CMP0211 OLD)
+
+include(CMP0211-Common.cmake)

Tests/RunCMake/target_sources/CMP0211-WARN-stderr.txt

@@ -0,0 +1,23 @@
+CMake Warning \(dev\) in CMakeLists\.txt:
+  Policy CMP0211 is not set: A file may belong to at most one file set in a
+  target\.  Run "cmake --help-policy CMP0211" for policy details\.  Use the
+  cmake_policy command to set the policy and suppress this warning\.
+
+  In target "foo1" the file
+
+    .+/Tests/RunCMake/target_sources/h1\.h
+
+  already belongs to file set "h2"\.
+This warning is for project developers\.  Use -Wno-dev to suppress it\.
+
+CMake Warning \(dev\) in CMakeLists\.txt:
+  Policy CMP0211 is not set: A file may belong to at most one file set in a
+  target\.  Run "cmake --help-policy CMP0211" for policy details\.  Use the
+  cmake_policy command to set the policy and suppress this warning\.
+
+  In target "foo2" the file
+
+    .+/Tests/RunCMake/target_sources/h1\.h
+
+  already belongs to file set "h1"\.
+This warning is for project developers\.  Use -Wno-dev to suppress it\.

Tests/RunCMake/target_sources/CMP0211-WARN.cmake

@@ -0,0 +1,2 @@
+
+include(CMP0211-Common.cmake)

Tests/RunCMake/target_sources/FileSetDuplicateSource.cmake

@@ -0,0 +1,6 @@
+enable_language(C)
+
+add_library(lib1 STATIC empty.c)
+
+# files are silently de-duplicated
+target_sources(lib1 PRIVATE FILE_SET HEADERS FILES h1.h h1.h)

Tests/RunCMake/target_sources/FileSetProperties.cmake

@@ -56,20 +56,20 @@ assert_prop_eq(lib1 HEADER_SET_d "")
 assert_prop_eq(lib1 INCLUDE_DIRECTORIES "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/.>;$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/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}>")
 
-target_sources(lib1 PUBLIC FILE_SET HEADERS BASE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}" FILES h1.h)
+target_sources(lib1 PUBLIC FILE_SET HEADERS BASE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}" FILES h4.h)
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a;c;d;HEADERS")
 assert_prop_eq(lib1 HEADER_DIRS "${CMAKE_CURRENT_SOURCE_DIR}")
-assert_prop_eq(lib1 HEADER_SET "${CMAKE_CURRENT_SOURCE_DIR}/h1.h")
+assert_prop_eq(lib1 HEADER_SET "${CMAKE_CURRENT_SOURCE_DIR}/h4.h")
 assert_prop_eq(lib1 HEADER_DIRS_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}")
-assert_prop_eq(lib1 HEADER_SET_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}/h1.h")
+assert_prop_eq(lib1 HEADER_SET_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}/h4.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 HEADERS FILES h2.h)
+target_sources(lib1 PUBLIC FILE_SET HEADERS FILES h5.h)
 assert_prop_eq(lib1 INTERFACE_HEADER_SETS "a;c;d;HEADERS")
 assert_prop_eq(lib1 HEADER_DIRS "${CMAKE_CURRENT_SOURCE_DIR}")
-assert_prop_eq(lib1 HEADER_SET "${CMAKE_CURRENT_SOURCE_DIR}/h1.h;${CMAKE_CURRENT_SOURCE_DIR}/h2.h")
+assert_prop_eq(lib1 HEADER_SET "${CMAKE_CURRENT_SOURCE_DIR}/h4.h;${CMAKE_CURRENT_SOURCE_DIR}/h5.h")
 assert_prop_eq(lib1 HEADER_DIRS_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}")
-assert_prop_eq(lib1 HEADER_SET_HEADERS "${CMAKE_CURRENT_SOURCE_DIR}/h1.h;${CMAKE_CURRENT_SOURCE_DIR}/h2.h")
+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}>")

Tests/RunCMake/target_sources/RunCMakeTest.cmake

@@ -43,9 +43,13 @@ run_cmake(FileSetCustomTarget)
 run_cmake(FileSetBadName)
 run_cmake(FileSetWrongSyntax)
 run_cmake(FileSetDirect)
+run_cmake(FileSetDuplicateSource)
 if(APPLE)
   run_cmake(FileSetFramework)
 endif()
+run_cmake(CMP0211-OLD)
+run_cmake(CMP0211-NEW)
+run_cmake(CMP0211-WARN)
 
 set(RunCMake_TEST_NO_CLEAN 1)
 set(RunCMake_TEST_BINARY_DIR "${RunCMake_BINARY_DIR}/FileSetGeneratedDependency-build")