Ninja: Remove shell workaround from compilation database

Commit 1528113bdf (instrumentation: Prevent inherited process metrics in
chained commands, 2026-09-14) added an extra command to successfully
track process metrics for instrumentation, working around shell exec
optimizations . However, this workaround gets exported into
`compile_commands.json` when using the Ninja generator, which breaks
some tools that consume the database.

Append this no-op command only when generating the actual build files.

Source/cmLocalNinjaGenerator.cxx

@@ -509,7 +509,7 @@ bool RuleNeedsCMD(std::string const& cmd)
 std::string cmLocalNinjaGenerator::BuildCommandLine(
   std::vector<std::string> const& cmdLines, std::string const& outputConfig,
   std::string const& commandConfig, std::string const& customStep,
-  cmGeneratorTarget const* target) const
+  cmGeneratorTarget const* target, CommandLineContext context) const
 {
   // If we have no commands but we need to build a command anyway, use noop.
   // This happens when building a POST_BUILD value for link targets that
@@ -549,6 +549,7 @@ std::string cmLocalNinjaGenerator::BuildCommandLine(
 
   std::ostringstream cmd;
 #ifdef _WIN32
+  (void)context;
   cmGlobalNinjaGenerator const* gg = this->GetGlobalNinjaGenerator();
   bool const needCMD =
     cmdLines.size() > 1 || (customStep.empty() && RuleNeedsCMD(cmdLines[0]));
@@ -577,12 +578,16 @@ std::string cmLocalNinjaGenerator::BuildCommandLine(
     cmd << *li;
   }
 #  ifndef CMAKE_BOOTSTRAP
-  if (this->GetCMakeInstance()->GetInstrumentation()->HasOption(
+  if (context == CommandLineContext::Build &&
+      this->GetCMakeInstance()->GetInstrumentation()->HasOption(
         cmInstrumentationQuery::Option::ProcessMetrics)) {
     // Prevent shell exec optimization from passing accumulated child resource
-    // usage to the final instrumentation wrapper.
+    // usage to the final instrumentation wrapper. Keep this build-only shell
+    // syntax out of compile_commands.json, for compiler tooling support
     cmd << " && :";
   }
+#  else
+  (void)context;
 #  endif
 #endif
   return cmd.str();

Source/cmLocalNinjaGenerator.h

@@ -65,11 +65,18 @@ public:
     cmStateEnums::IntermediateDirKind kind =
       cmStateEnums::IntermediateDirKind::ObjectFiles) const override;
 
+  enum class CommandLineContext
+  {
+    Build,
+    CompileCommands
+  };
+
   std::string BuildCommandLine(
     std::vector<std::string> const& cmdLines, std::string const& outputConfig,
     std::string const& commandConfig,
     std::string const& customStep = std::string(),
-    cmGeneratorTarget const* target = nullptr) const;
+    cmGeneratorTarget const* target = nullptr,
+    CommandLineContext context = CommandLineContext::Build) const;
 
   void AppendTargetOutputs(cmGeneratorTarget* target, cmNinjaDeps& outputs,
                            std::string const& config);

Source/cmNinjaTargetGenerator.cxx

@@ -2682,7 +2682,8 @@ void cmNinjaTargetGenerator::ExportObjectCompileCommand(
   }
 
   std::string cmdLine = this->GetLocalGenerator()->BuildCommandLine(
-    compileCmds, outputConfig, outputConfig);
+    compileCmds, outputConfig, outputConfig, {}, nullptr,
+    cmLocalNinjaGenerator::CommandLineContext::CompileCommands);
 
   this->GetGlobalGenerator()->AddCXXCompileCommand(cmdLine, sourceFileName,
                                                    objectFileName);
@@ -2755,7 +2756,8 @@ void cmNinjaTargetGenerator::ExportSwiftObjectCompileCommand(
     }
 
     std::string commandLine = this->GetLocalGenerator()->BuildCommandLine(
-      compileCmds, outputConfig, outputConfig);
+      compileCmds, outputConfig, outputConfig, {}, nullptr,
+      cmLocalNinjaGenerator::CommandLineContext::CompileCommands);
 
     this->GetGlobalGenerator()->AddCXXCompileCommand(
       commandLine, sourceFilename, objectFilename);

Tests/RunCMake/Instrumentation/check-data-dir.cmake

@@ -342,3 +342,49 @@ if (ARGS_BUILD_MAKE_PROGRAM)
     add_error("No snippet files of role \"build\" were found in ${v1}")
   endif()
 endif()
+
+if (ARGS_PROCESS_METRICS_QUERY)
+  # The process-metrics "&& :" suffix belongs only in build-tool shell commands,
+  # not exported compile commands.
+  set(compilation_database "${RunCMake_TEST_BINARY_DIR}/compile_commands.json")
+  if (EXISTS "${compilation_database}")
+    file(READ "${compilation_database}" compile_commands)
+    string(JSON command_count LENGTH "${compile_commands}")
+    if (command_count GREATER 0)
+      math(EXPR last_command "${command_count} - 1")
+      foreach(i RANGE 0 ${last_command})
+        string(JSON arguments_type ERROR_VARIABLE no_arguments
+          TYPE "${compile_commands}" ${i} arguments)
+        if (arguments_type STREQUAL "ARRAY")
+          # FASTBuild exports an argument array rather than a command string.
+          set(arguments)
+          string(JSON argument_count LENGTH "${compile_commands}" ${i} arguments)
+          if (argument_count GREATER 0)
+            math(EXPR last_argument "${argument_count} - 1")
+            foreach(j RANGE 0 ${last_argument})
+              string(JSON argument GET "${compile_commands}" ${i} arguments ${j})
+              list(APPEND arguments "${argument}")
+            endforeach()
+          endif()
+        else()
+          string(JSON command GET "${compile_commands}" ${i} command)
+          separate_arguments(arguments NATIVE_COMMAND "${command}")
+        endif()
+        list(LENGTH arguments argument_count)
+        if (argument_count EQUAL 0)
+          add_error("Compile command ${i} has no arguments")
+        elseif (argument_count GREATER_EQUAL 2)
+          list(GET arguments -2 penultimate_argument)
+          list(GET arguments -1 last_argument)
+          if (penultimate_argument STREQUAL "&&" AND last_argument STREQUAL ":")
+            add_error("Compile command contains process-metrics shell suffix: ${arguments}")
+          endif()
+        endif()
+      endforeach()
+    else()
+      add_error("No commands in ${compilation_database}")
+    endif()
+  else()
+    add_error("Missing ${compilation_database}")
+  endif()
+endif()

Tests/RunCMake/Instrumentation/query/cmake-command-process-metrics.cmake

@@ -1,4 +1,5 @@
 set_property(GLOBAL PROPERTY INSTALL_PARALLEL ON)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 cmake_instrumentation(
   API_VERSION 1
   DATA_VERSION 1.2