write C++ modules summary

Author: bkietz

build.rst

@@ -456,7 +456,12 @@ function(_maud_scan source_file)
   message(VERBOSE "  attaching to ${target_name}")
 
   set_property(TARGET ${target_name} APPEND PROPERTY MAUD_IMPORTS "${imports}")
-  set_target_properties(${target_name} PROPERTIES MAUD_SCANNED ON)
+  set_target_properties(
+    ${target_name}
+    PROPERTIES
+    MAUD_SCANNED ON
+    MAUD_MODULE "${module}"
+  )
   target_compile_features(
     ${target_name}
     PUBLIC
@@ -533,7 +538,7 @@ function(_maud_add_test source_file out_target_name)
   add_test(NAME test_.${name} COMMAND $<TARGET_FILE:test_.${name}> --gtest_brief=1)
   target_sources(
     test_.${name}
-    PRIVATE
+    PUBLIC
     FILE_SET module_providers
     TYPE CXX_MODULES
     ${_MAUD_BASE_DIRS}
@@ -542,7 +547,6 @@ function(_maud_add_test source_file out_target_name)
   set_target_properties(
     test_.${name}
     PROPERTIES
-    MAUD_INTERFACE "${_MAUD_SELF_DIR}/test_.cxx"
     COMPILE_OPTIONS "${_MAUD_INCLUDE} ${_MAUD_SELF_DIR}/test_.hxx"
   )
 endfunction()
@@ -611,6 +615,10 @@ function(_maud_finalize_targets)
     if(NOT imports)
       set(imports "")
     endif()
+    get_target_property(module ${target} MAUD_MODULE)
+    if(module AND target_type STREQUAL "EXECUTABLE")
+      list(APPEND imports "${module}")
+    endif()
     message(VERBOSE "  IMPORTS: ${imports}")
 
     # Link targets to imported modules
@@ -629,10 +637,9 @@ function(_maud_finalize_targets)
     endforeach()
 
     get_target_property(interface ${target} MAUD_INTERFACE)
-    if(NOT interface)
+    if(NOT interface AND NOT TEST ${target})
       if(target_type STREQUAL "EXECUTABLE")
         set(interface "${_MAUD_SELF_DIR}/executable.cxx")
-        set(source_access PRIVATE)
       else()
         get_target_property(src ${target} MAUD_INTERFACE_PARTITIONS)
         set(interface "${MAUD_DIR}/injected/${target}.cxx")
@@ -644,18 +651,18 @@ function(_maud_finalize_targets)
           PROPERTIES
           MAUD_TYPE INTERFACE
         )
-        set(source_access PUBLIC)
         message(VERBOSE "  No primary interface supplied, injecting ${interface}")
       endif()
       target_sources(
         ${target}
-        ${source_access}
+        PUBLIC
         FILE_SET module_providers
         TYPE CXX_MODULES
         ${_MAUD_BASE_DIRS}
         FILES "${interface}"
       )
     endif()
+
     print_target_sources(${target})
 
     if(TEST ${target} AND NOT COMMAND "maud_add_test")
@@ -669,7 +676,7 @@ function(_maud_finalize_targets)
 
       target_sources(
         ${target}
-        PRIVATE
+        PUBLIC
         FILE_SET module_providers
         TYPE CXX_MODULES
         BASE_DIRS ${_MAUD_BASE_DIRS}

cmake_modules/Maud.cmake

@@ -68,75 +68,6 @@ configuration options:
 
 Read more about :ref:`options`.
 
-Preprocessing
--------------
-
-By default, maud uses a custom module scanner which ignores preprocessing
-for efficiency and stops reading source files after the import declarations.
-This works in the most common case where the preprocessor only encounters
-``#include`` directives and an occasional ``#define``, which leaves
-the module dependency graph unaffected. However it is possible for the
-preprocessor to affect module and import declarations. For example:
-
-- an import declaration could be inside a conditional preprocessing block
-
-.. code-block:: cpp
-
-  module foo;
-  #if BAR_VERSION >= 3
-  import bar;
-  #endif
-
-- a set of import declarations could be included
-
-.. code-block:: cpp
-
-  module foo;
-  #include "common_imports.hxx"
-
-- a macro could expand to a pragma directive which modifies an ``#include``
-
-.. code-block:: cpp
-
-  module;
-  #include "macros.hxx"
-  PUSH_INGORED_WARNING(-Wunused-variable);
-  #include "dodgy.hxx"
-  POP_INGORED_WARNING();
-  module foo;
-
-- a macro could be used to derive the name of the module
-
-.. code-block:: cpp
-
-  module;
-  #include "macros.hxx"
-  module PP_CAT(foo_, FOO_VERSION);
-
-(I'm actually not sure that the last two are even legal since a global
-module fragment should exclusively contain preprocessing directives
-:cxx20:`module.global.frag#1`, however clang allows both.)
-
-IMHO, it is not desirable to write interface blocks which depend on preprocessing.
-Moreover C++26 will restrict usage of the preprocessor severely in module declarations
-as described in `P3034R1 <https://isocpp.org/files/papers/P3034R1.html>`_.
-
-.. _maud-preprocessing-scan-options:
-
-For source files which require it, the property ``MAUD_PREPROCESSING_SCAN_OPTIONS``
-can be set in cmake. This property should contain all compile options
-necessary to correctly preprocess the source file, for example
-``-I /home/i/foo/include -isystem /home/i/boost/include -DFOO_ENABLE_BAR=1``.
-
-Note that the output of these tools is in the JSON format described by `p1689
-<https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p1689r5.html>`_
-and does not distinguish between a module implementation unit of ``foo`` from a
-source file which happens to import ``foo``. Without information about which module
-an implementation unit is associated with, it cannot be automatically added to
-the corresponding target. As a workaround if you must have a preprocessing scan
-of an implementation unit, you can split the implementation unit into partitions
-whose primary module is exposed.
-
 Built-in support for generated files
 ------------------------------------