cmake_file_api: New project command

Projects can use the new command to request file API replies for the current
run. No query files are generated, the query is tracked internally. Replies are
created in the file system at generation time in the usual way.

Fixes: #24951

Help/command/cmake_file_api.rst

@@ -0,0 +1,78 @@
+cmake_file_api
+--------------
+
+.. versionadded:: 3.27
+
+Enables interacting with the :manual:`CMake file API <cmake-file-api(7)>`.
+
+.. signature::
+  cmake_file_api(QUERY ...)
+
+  The ``QUERY`` subcommand adds a file API query for the current CMake
+  invocation.
+
+  .. code-block:: cmake
+
+    cmake_file_api(
+      QUERY
+      API_VERSION <version>
+      [CODEMODEL <versions>...]
+      [CACHE <versions>...]
+      [CMAKEFILES <versions>...]
+      [TOOLCHAINS <versions>...]
+    )
+
+  The ``API_VERSION`` must always be given.  Currently, the only supported
+  value for ``<version>`` is 1.  See :ref:`file-api v1` for details of the
+  reply content and location.
+
+  Each of the optional keywords ``CODEMODEL``, ``CACHE``, ``CMAKEFILES`` and
+  ``TOOLCHAINS`` correspond to one of the object kinds that can be requested
+  by the project.  The ``configureLog`` object kind cannot be set with this
+  command, since it must be set before CMake starts reading the top level
+  ``CMakeLists.txt`` file.
+
+  For each of the optional keywords, the ``<versions>`` list must contain one
+  or more version values of the form ``major`` or ``major.minor``, where
+  ``major`` and ``minor`` are integers.  Projects should list the versions they
+  accept in their preferred order, as only the first supported value from the
+  list will be selected.  The command will ignore versions with a ``major``
+  version higher than any major version it supports for that object kind.
+  It will raise an error if it encounters an invalid version number, or if none
+  of the requested versions is supported.
+
+  For each type of object kind requested, a query equivalent to a shared,
+  stateless query will be added internally.  No query file will be created in
+  the file system.  The reply *will* be written to the file system at
+  generation time.
+
+  It is not an error to add a query for the same thing more than once, whether
+  from query files or from multiple calls to ``cmake_file_api(QUERY)``.
+  The final set of queries will be a merged combination of all queries
+  specified on disk and queries submitted by the project.
+
+Example
+^^^^^^^
+
+A project may want to use replies from the file API at build time to implement
+some form of verification task.  Instead of relying on something outside of
+CMake to create a query file, the project can use ``cmake_file_api(QUERY)``
+to request the required information for the current run.  It can then create
+a custom command to run at build time, knowing that the requested information
+should always be available.
+
+.. code-block:: cmake
+
+  cmake_file_api(
+    QUERY
+    API_VERSION 1
+    CODEMODEL 2.3
+    TOOLCHAINS 1
+  )
+
+  add_custom_target(verify_project
+    COMMAND ${CMAKE_COMMAND}
+      -D BUILD_DIR=${CMAKE_BINARY_DIR}
+      -D CONFIG=$<CONFIG>
+      -P ${CMAKE_CURRENT_SOURCE_DIR}/verify_project.cmake
+  )

Help/manual/cmake-commands.7.rst

@@ -87,6 +87,7 @@ These commands are available only in CMake projects.
    /command/add_test
    /command/aux_source_directory
    /command/build_command
+   /command/cmake_file_api
    /command/create_test_sourcelist
    /command/define_property
    /command/enable_language

Help/manual/cmake-file-api.7.rst

@@ -23,6 +23,12 @@ of files within the API directory.  API file layout versioning is
 orthogonal to the versioning of `Object Kinds`_ used in replies.
 This version of CMake supports only one API version, `API v1`_.
 
+.. versionadded:: 3.27
+  Projects may also submit queries for the current run using the
+  :command:`cmake_file_api` command.
+
+.. _`file-api v1`:
+
 API v1
 ======
 

Help/release/dev/file-api-query-command.rst

@@ -0,0 +1,6 @@
+file-api-query-command
+----------------------
+
+* The :command:`cmake_file_api` command was added, enabling projects to
+  add :manual:`CMake file API <cmake-file-api(7)>` queries for the current
+  CMake run.

Source/CMakeLists.txt

@@ -232,6 +232,8 @@ add_library(
   cmFileAPIConfigureLog.h
   cmFileAPICMakeFiles.cxx
   cmFileAPICMakeFiles.h
+  cmFileAPICommand.cxx
+  cmFileAPICommand.h
   cmFileAPIToolchains.cxx
   cmFileAPIToolchains.h
   cmFileCopier.cxx

Source/cmCommands.cxx

@@ -97,6 +97,7 @@
 #  include "cmExportCommand.h"
 #  include "cmExportLibraryDependenciesCommand.h"
 #  include "cmFLTKWrapUICommand.h"
+#  include "cmFileAPICommand.h"
 #  include "cmIncludeExternalMSProjectCommand.h"
 #  include "cmInstallProgramsCommand.h"
 #  include "cmLinkLibrariesCommand.h"
@@ -293,6 +294,7 @@ void GetProjectCommands(cmState* state)
   state->AddBuiltinCommand("qt_wrap_ui", cmQTWrapUICommand);
   state->AddBuiltinCommand("remove_definitions", cmRemoveDefinitionsCommand);
   state->AddBuiltinCommand("source_group", cmSourceGroupCommand);
+  state->AddBuiltinCommand("cmake_file_api", cmFileAPICommand);
 
   state->AddDisallowedCommand(
     "export_library_dependencies", cmExportLibraryDependenciesCommand,
@@ -333,6 +335,7 @@ void GetProjectCommandsInScriptMode(cmState* state)
   CM_UNEXPECTED_PROJECT_COMMAND("add_test");
   CM_UNEXPECTED_PROJECT_COMMAND("aux_source_directory");
   CM_UNEXPECTED_PROJECT_COMMAND("build_command");
+  CM_UNEXPECTED_PROJECT_COMMAND("cmake_file_api");
   CM_UNEXPECTED_PROJECT_COMMAND("create_test_sourcelist");
   CM_UNEXPECTED_PROJECT_COMMAND("define_property");
   CM_UNEXPECTED_PROJECT_COMMAND("enable_language");

Source/cmFileAPI.cxx

@@ -978,3 +978,45 @@ Json::Value cmFileAPI::ReportCapabilities()
 
   return capabilities;
 }
+
+bool cmFileAPI::AddProjectQuery(cmFileAPI::ObjectKind kind,
+                                unsigned majorVersion, unsigned minorVersion)
+{
+  switch (kind) {
+    case ObjectKind::CodeModel:
+      if (majorVersion != 2 || minorVersion > CodeModelV2Minor) {
+        return false;
+      }
+      break;
+    case ObjectKind::Cache:
+      if (majorVersion != 2 || minorVersion > CacheV2Minor) {
+        return false;
+      }
+      break;
+    case ObjectKind::CMakeFiles:
+      if (majorVersion != 1 || minorVersion > CMakeFilesV1Minor) {
+        return false;
+      }
+      break;
+    case ObjectKind::Toolchains:
+      if (majorVersion != 1 || minorVersion > ToolchainsV1Minor) {
+        return false;
+      }
+      break;
+    // These cannot be requested by the project
+    case ObjectKind::ConfigureLog:
+    case ObjectKind::InternalTest:
+      return false;
+  }
+
+  Object query;
+  query.Kind = kind;
+  query.Version = majorVersion;
+  if (std::find(this->TopQuery.Known.begin(), this->TopQuery.Known.end(),
+                query) == this->TopQuery.Known.end()) {
+    this->TopQuery.Known.emplace_back(query);
+    this->QueryExists = true;
+  }
+
+  return true;
+}

Source/cmFileAPI.h

@@ -41,6 +41,20 @@ public:
   /** Report file-api capabilities for cmake -E capabilities.  */
   static Json::Value ReportCapabilities();
 
+  // Keep in sync with ObjectKindName.
+  enum class ObjectKind
+  {
+    CodeModel,
+    ConfigureLog,
+    Cache,
+    CMakeFiles,
+    Toolchains,
+    InternalTest
+  };
+
+  bool AddProjectQuery(ObjectKind kind, unsigned majorVersion,
+                       unsigned minorVersion);
+
 private:
   cmake* CMakeInstance;
 
@@ -53,17 +67,6 @@ private:
   static std::vector<std::string> LoadDir(std::string const& dir);
   void RemoveOldReplyFiles();
 
-  // Keep in sync with ObjectKindName.
-  enum class ObjectKind
-  {
-    CodeModel,
-    ConfigureLog,
-    Cache,
-    CMakeFiles,
-    Toolchains,
-    InternalTest
-  };
-
   /** Identify one object kind and major version.  */
   struct Object
   {
@@ -76,6 +79,14 @@ private:
       }
       return l.Version < r.Version;
     }
+    friend bool operator==(Object const& l, Object const& r)
+    {
+      return l.Kind == r.Kind && l.Version == r.Version;
+    }
+    friend bool operator!=(Object const& l, Object const& r)
+    {
+      return !(l == r);
+    }
   };
 
   /** Represent content of a query directory.  */

Source/cmFileAPICommand.cxx

@@ -0,0 +1,170 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmFileAPICommand.h"
+
+#include <algorithm>
+#include <array>
+#include <cctype>
+#include <cstdlib>
+
+#include <cm/string_view>
+#include <cmext/string_view>
+
+#include "cmArgumentParser.h"
+#include "cmArgumentParserTypes.h"
+#include "cmExecutionStatus.h"
+#include "cmFileAPI.h"
+#include "cmMakefile.h"
+#include "cmRange.h"
+#include "cmStringAlgorithms.h"
+#include "cmSubcommandTable.h"
+#include "cmake.h"
+
+namespace {
+
+bool isCharDigit(char ch)
+{
+  return std::isdigit(static_cast<unsigned char>(ch));
+}
+
+std::string processObjectKindVersions(cmFileAPI& fileApi,
+                                      cmFileAPI::ObjectKind objectKind,
+                                      cm::string_view keyword,
+                                      const std::vector<std::string>& versions)
+{
+  // The "versions" vector is empty only when the keyword was not present.
+  // It is an error to provide the keyword with no versions after it, and that
+  // is enforced by the argument parser before we get here.
+  if (versions.empty()) {
+    return {};
+  }
+
+  // The first supported version listed is what we use
+  for (const std::string& ver : versions) {
+    const char* vStart = ver.c_str();
+    int majorVersion = std::atoi(vStart);
+    int minorVersion = 0;
+    std::string::size_type pos = ver.find('.');
+    if (pos != std::string::npos) {
+      vStart += pos + 1;
+      minorVersion = std::atoi(vStart);
+    }
+    if (majorVersion < 1 || minorVersion < 0) {
+      return cmStrCat("Given a malformed version \"", ver, "\" for ", keyword,
+                      ".");
+    }
+    if (fileApi.AddProjectQuery(objectKind,
+                                static_cast<unsigned>(majorVersion),
+                                static_cast<unsigned>(minorVersion))) {
+      return {};
+    }
+  }
+  return cmStrCat("None of the specified ", keyword,
+                  " versions is supported by this version of CMake.");
+}
+
+bool handleQueryCommand(std::vector<std::string> const& args,
+                        cmExecutionStatus& status)
+{
+  if (args.empty()) {
+    status.SetError("QUERY subcommand called without required arguments.");
+    return false;
+  }
+
+  struct Arguments : public ArgumentParser::ParseResult
+  {
+    ArgumentParser::NonEmpty<std::string> ApiVersion;
+    ArgumentParser::NonEmpty<std::vector<std::string>> CodeModelVersions;
+    ArgumentParser::NonEmpty<std::vector<std::string>> CacheVersions;
+    ArgumentParser::NonEmpty<std::vector<std::string>> CMakeFilesVersions;
+    ArgumentParser::NonEmpty<std::vector<std::string>> ToolchainsVersions;
+  };
+
+  static auto const parser =
+    cmArgumentParser<Arguments>{}
+      .Bind("API_VERSION"_s, &Arguments::ApiVersion)
+      .Bind("CODEMODEL"_s, &Arguments::CodeModelVersions)
+      .Bind("CACHE"_s, &Arguments::CacheVersions)
+      .Bind("CMAKEFILES"_s, &Arguments::CMakeFilesVersions)
+      .Bind("TOOLCHAINS"_s, &Arguments::ToolchainsVersions);
+
+  std::vector<std::string> unparsedArguments;
+  Arguments const arguments =
+    parser.Parse(cmMakeRange(args).advance(1), &unparsedArguments);
+
+  if (arguments.MaybeReportError(status.GetMakefile())) {
+    return true;
+  }
+  if (!unparsedArguments.empty()) {
+    status.SetError("QUERY subcommand given unknown argument \"" +
+                    unparsedArguments.front() + "\".");
+    return false;
+  }
+
+  if (!std::all_of(arguments.ApiVersion.begin(), arguments.ApiVersion.end(),
+                   isCharDigit)) {
+    status.SetError("QUERY subcommand given a non-integer API_VERSION.");
+    return false;
+  }
+  const int apiVersion = std::atoi(arguments.ApiVersion.c_str());
+  if (apiVersion != 1) {
+    status.SetError(
+      cmStrCat("QUERY subcommand given an unsupported API_VERSION \"",
+               arguments.ApiVersion,
+               "\" (the only currently supported version is 1)."));
+    return false;
+  }
+
+  cmMakefile& mf = status.GetMakefile();
+  cmake* cmi = mf.GetCMakeInstance();
+  cmFileAPI* fileApi = cmi->GetFileAPI();
+
+  // We want to check all keywords and report all errors, not just the first.
+  // Record each result rather than short-circuiting on the first error.
+
+  // NOTE: Double braces are needed here for compilers that don't implement the
+  // CWG 1270 revision to C++11.
+  std::array<std::string, 4> errors{
+    { processObjectKindVersions(*fileApi, cmFileAPI::ObjectKind::CodeModel,
+                                "CODEMODEL"_s, arguments.CodeModelVersions),
+      processObjectKindVersions(*fileApi, cmFileAPI::ObjectKind::Cache,
+                                "CACHE"_s, arguments.CacheVersions),
+      processObjectKindVersions(*fileApi, cmFileAPI::ObjectKind::CMakeFiles,
+                                "CMAKEFILES"_s, arguments.CMakeFilesVersions),
+      processObjectKindVersions(*fileApi, cmFileAPI::ObjectKind::Toolchains,
+                                "TOOLCHAINS"_s, arguments.ToolchainsVersions) }
+  };
+
+  if (!std::all_of(errors.begin(), errors.end(),
+                   [](const std::string& s) -> bool { return s.empty(); })) {
+    std::string message("QUERY subcommand was given invalid arguments:");
+    for (const std::string& s : errors) {
+      if (!s.empty()) {
+        message = cmStrCat(message, "\n  ", s);
+      }
+    }
+    status.SetError(message);
+    return false;
+  }
+
+  return true;
+}
+
+}
+
+bool cmFileAPICommand(std::vector<std::string> const& args,
+                      cmExecutionStatus& status)
+{
+  if (args.empty()) {
+    status.SetError("must be called with arguments.");
+    return false;
+  }
+
+  // clang-format off
+  static cmSubcommandTable const subcommand{
+    { "QUERY"_s, handleQueryCommand }
+  };
+  // clang-format on
+
+  return subcommand(args[0], args, status);
+}

Source/cmFileAPICommand.h

@@ -0,0 +1,13 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <string>
+#include <vector>
+
+class cmExecutionStatus;
+
+bool cmFileAPICommand(std::vector<std::string> const& args,
+                      cmExecutionStatus& status);

Source/cmake.h

@@ -635,6 +635,10 @@ public:
   void UnwatchUnusedCli(const std::string& var);
   void WatchUnusedCli(const std::string& var);
 
+#if !defined(CMAKE_BOOTSTRAP)
+  cmFileAPI* GetFileAPI() const { return this->FileAPI.get(); }
+#endif
+
   cmState* GetState() const { return this->State.get(); }
   void SetCurrentSnapshot(cmStateSnapshot const& snapshot)
   {

Tests/RunCMake/FileAPI/ProjectQueryBad-result.txt

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

Tests/RunCMake/FileAPI/ProjectQueryBad-stderr.txt

@@ -0,0 +1,36 @@
+Non-query check
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api does not recognize sub-command NOT_A_QUERY
+.*
+Invalid API version checks
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api QUERY subcommand given an unsupported API_VERSION "2" \(the
+  only currently supported version is 1\)\.
+.*
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api QUERY subcommand given a non-integer API_VERSION\.
+.*
+Invalid version numbers check
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api QUERY subcommand was given invalid arguments:
+
+    Given a malformed version "nope" for CODEMODEL\.
+    Given a malformed version "-2" for CACHE\.
+    Given a malformed version "\.8" for CMAKEFILES\.
+    Given a malformed version "0\.1" for TOOLCHAINS\.
+.*
+Requested versions too high check
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api QUERY subcommand was given invalid arguments:
+
+    None of the specified CODEMODEL versions is supported by this version of CMake\.
+    None of the specified CACHE versions is supported by this version of CMake\.
+    None of the specified CMAKEFILES versions is supported by this version of CMake\.
+    None of the specified TOOLCHAINS versions is supported by this version of CMake\.
+.*
+Requested versions too low check
+CMake Error at ProjectQueryBad\.cmake:[0-9]+ \(cmake_file_api\):
+  cmake_file_api QUERY subcommand was given invalid arguments:
+
+    None of the specified CODEMODEL versions is supported by this version of CMake\.
+    None of the specified CACHE versions is supported by this version of CMake\.

Tests/RunCMake/FileAPI/ProjectQueryBad.cmake

@@ -0,0 +1,42 @@
+# All of these should fail. Execution does continue though, so we should see
+# the error output from each one. There is no observable effect of the command
+# during the configure phase, so it isn't critical to end processing on the
+# first failure. Allowing execution to proceed may allow the project to see
+# other potential errors before ultimately halting. That behavior is generally
+# desirable, and the multiple failing calls here will confirm that we retain
+# that behavior.
+
+message(NOTICE "Non-query check")
+cmake_file_api(NOT_A_QUERY)
+
+message(NOTICE "Invalid API version checks")
+cmake_file_api(QUERY API_VERSION 2)
+cmake_file_api(QUERY API_VERSION nah)
+
+message(NOTICE "Invalid version numbers check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL nope
+  CACHE -2
+  CMAKEFILES .8
+  TOOLCHAINS 2 0.1
+)
+
+message(NOTICE "Requested versions too high check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL 3
+  CACHE 3
+  CMAKEFILES 2
+  TOOLCHAINS 1.1
+)
+
+message(NOTICE "Requested versions too low check")
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL 1
+  CACHE 1
+)

Tests/RunCMake/FileAPI/ProjectQueryGood-check.cmake

@@ -0,0 +1,11 @@
+set(expect
+  reply
+  reply/cache-v2-[0-9a-f]+.json
+  reply/cmakeFiles-v1-[0-9a-f]+.json
+  reply/codemodel-v2-[0-9a-f]+.json
+  .*reply/index-[0-9.T-]+.json
+  .*reply/toolchains-v1-[0-9a-f]+.json
+)
+
+# Only need to check for existence. Other tests check the reply contents.
+check_api("^${expect}$")

Tests/RunCMake/FileAPI/ProjectQueryGood.cmake

@@ -0,0 +1,8 @@
+cmake_file_api(
+  QUERY
+  API_VERSION 1
+  CODEMODEL 3 2.1
+  CACHE 3.2 2
+  CMAKEFILES 3 2 1.0
+  TOOLCHAINS 3 2 1
+)

Tests/RunCMake/FileAPI/RunCMakeTest.cmake

@@ -52,6 +52,8 @@ run_cmake(ClientStateless)
 run_cmake(MixedStateless)
 run_cmake(DuplicateStateless)
 run_cmake(ClientStateful)
+run_cmake(ProjectQueryGood)
+run_cmake(ProjectQueryBad)
 
 function(run_object object)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${object}-build)