execute_process: Add options for modified environment

Help/command/execute_process.rst

@@ -22,6 +22,8 @@ Execute one or more child processes.
                   [OUTPUT_STRIP_TRAILING_WHITESPACE]
                   [ERROR_STRIP_TRAILING_WHITESPACE]
                   [ENCODING <name>]
+                  [ENVIRONMENT <variable=value>...]
+                  [ENVIRONMENT_MODIFICATION <env-mod-op>...]
                   [ECHO_OUTPUT_VARIABLE]
                   [ECHO_ERROR_VARIABLE]
                   [COMMAND_ERROR_IS_FATAL <ANY|LAST|NONE>])
@@ -187,6 +189,27 @@ Options:
    `UTF-8 RFC <https://datatracker.ietf.org/doc/html/rfc3629>`_
    naming convention.
 
+``ENVIRONMENT <variable=value>...``
+  .. versionadded:: 4.4
+
+  Add environment variable definitions to the environment of the child
+  processes.  Each entry must be of the form ``NAME=value`` and is interpreted
+  as setting ``NAME`` to ``value`` for the duration of the
+  ``execute_process()`` call.
+
+  These entries are processed in order.  If the same variable name is given
+  multiple times, the last value wins.
+
+``ENVIRONMENT_MODIFICATION <env-mod-op>...``
+  .. versionadded:: 4.4
+
+  Apply one or more :prop_test:`ENVIRONMENT_MODIFICATION` operations to the
+  environment of the child processes.  Each operation is applied in the given
+  order, and failures to parse an operation are treated as errors.
+
+  Environment modifications are applied after ``ENVIRONMENT`` entries, if both
+  options are specified.
+
 ``COMMAND_ERROR_IS_FATAL <ANY|LAST|NONE>``
   .. versionadded:: 3.19
 

Help/release/dev/execute_process-environment.rst

@@ -0,0 +1,6 @@
+execute_process-environment
+---------------------------
+
+* The :command:`execute_process` command learned the
+  ``ENVIRONMENT`` and ``ENVIRONMENT_MODIFICATION`` options to run child
+  processes with a modified environment.

Source/cmExecuteProcessCommand.cxx

@@ -27,6 +27,8 @@
 #include "cmsys/String.h"
 
 #include "cmArgumentParser.h"
+#include "cmArgumentParserTypes.h"
+#include "cmEnvironment.h"
 #include "cmExecutionStatus.h"
 #include "cmList.h"
 #include "cmMakefile.h"
@@ -94,6 +96,8 @@ bool cmExecuteProcessCommand(std::vector<std::string> const& args,
     bool EchoOutputVariable = false;
     bool EchoErrorVariable = false;
     cm::optional<std::string> Encoding;
+    ArgumentParser::MaybeEmpty<std::vector<std::string>> Environment;
+    ArgumentParser::MaybeEmpty<std::vector<std::string>> EnvModification;
     std::string CommandErrorIsFatal;
   };
 
@@ -117,6 +121,8 @@ bool cmExecuteProcessCommand(std::vector<std::string> const& args,
       .Bind("ERROR_STRIP_TRAILING_WHITESPACE"_s,
             &Arguments::ErrorStripTrailingWhitespace)
       .Bind("ENCODING"_s, &Arguments::Encoding)
+      .Bind("ENVIRONMENT"_s, &Arguments::Environment)
+      .Bind("ENVIRONMENT_MODIFICATION"_s, &Arguments::EnvModification)
       .Bind("ECHO_OUTPUT_VARIABLE"_s, &Arguments::EchoOutputVariable)
       .Bind("ECHO_ERROR_VARIABLE"_s, &Arguments::EchoErrorVariable)
       .Bind("COMMAND_ERROR_IS_FATAL"_s, &Arguments::CommandErrorIsFatal);
@@ -213,6 +219,23 @@ bool cmExecuteProcessCommand(std::vector<std::string> const& args,
     builder.SetWorkingDirectory(arguments.WorkingDirectory);
   }
 
+  if (!arguments.Environment.empty() || !arguments.EnvModification.empty()) {
+#ifndef CMAKE_BOOTSTRAP
+    auto diff = cmEnvironmentModification{};
+    if (!diff.Add(arguments.EnvModification)) {
+      return false;
+    }
+    auto env = cmEnvironment{ cmSystemTools::GetEnvironmentVariables() };
+    env.Update(arguments.Environment);
+    diff.ApplyTo(env);
+    builder.SetEnvironment(env.GetVariables());
+#else
+    status.SetError(
+      "does not support environment modification in bootstrap builds");
+    return false;
+#endif
+  }
+
   // Check the output variables.
   std::unique_ptr<FILE, int (*)(FILE*)> inputFile(nullptr, fclose);
   if (!inputFilename.empty()) {

Tests/RunCMake/execute_process/Environment-stdout.txt

@@ -0,0 +1 @@
+CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT=expected_value

Tests/RunCMake/execute_process/Environment.cmake

@@ -0,0 +1,5 @@
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E environment
+  ENVIRONMENT
+    "CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT=expected_value"
+  )

Tests/RunCMake/execute_process/EnvironmentModification-stdout.txt

@@ -0,0 +1 @@
+CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT=kaesekuchen

Tests/RunCMake/execute_process/EnvironmentModification.cmake

@@ -0,0 +1,6 @@
+set(ENV{CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT} "kaese")
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E environment
+  ENVIRONMENT_MODIFICATION
+    "CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT=string_append:kuchen"
+  )

Tests/RunCMake/execute_process/EnvironmentModificationError-result.txt

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

Tests/RunCMake/execute_process/EnvironmentModificationError-stderr.txt

@@ -0,0 +1 @@
+CMake Error: Error: Unrecognized environment manipulation argument: invalid

Tests/RunCMake/execute_process/EnvironmentModificationError.cmake

@@ -0,0 +1,5 @@
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E environment
+  ENVIRONMENT_MODIFICATION
+    "CMAKE_TEST_RUNCMAKE_EXECUTE_PROCESS_ENVIRONMENT=invalid:value"
+  )

Tests/RunCMake/execute_process/RunCMakeTest.cmake

@@ -19,6 +19,10 @@ if(TEST_ENCODING_EXE)
   run_cmake_script(EncodingUTF8 -DTEST_ENCODING_EXE=${TEST_ENCODING_EXE})
 endif()
 
+run_cmake(Environment)
+run_cmake(EnvironmentModification)
+run_cmake(EnvironmentModificationError)
+
 if(EXIT_CODE_EXE)
   run_cmake_command(ExitValues ${CMAKE_COMMAND} -DEXIT_CODE_EXE=${EXIT_CODE_EXE} -P ${RunCMake_SOURCE_DIR}/ExitValues.cmake)
 endif()