[Fortran/gfortran] Fix build-time and test-time race conditions

Use a dedicated module directory for each test. Any .mod files generated by the
test at build-time will be written into this directory. The same directory is
also used as the working directory for the the tests at test-time. Any files
created/read/written by the test at test-time reside in that directory. This
ensures that the tests don't race on the file system when run in parallel.

The tests that were previously disabled because of these races have been
re-enabled.

This fixes PR #63263 (llvm/llvm-project#63263)

Differential Revision: https://reviews.llvm.org/D152307

Author: tarunprabhu

Fortran/gfortran/CMakeLists.txt

@@ -239,10 +239,11 @@ endfunction()
 
 function(gfortran_execute_test File)
   cmake_parse_arguments(GFORTRAN "" "PREFIX" "FFLAGS;LDFLAGS;DEPFILES" ${ARGN})
-  # There are a few tests with duplicate filenames, and CMake wants all target
-  # names to be unique, so we add a disambiguator to the target name. The
+  # There are a few tests - in different directories - with duplicate filenames.
+  # CMake requires all target names to be unique, so we add a disambiguator. The
   # disambiguator uses the path of the file relative to the top-level directory
-  # containing all the tests from the gfortran test suite.
+  # containing all the tests from the gfortran test suite to ensure that
+  # targets in different directories will have distinct names.
 
   # The ${File} argument is guaranteed to be the absolute path to the source
   # file.
@@ -260,19 +261,38 @@ function(gfortran_execute_test File)
   # tests.
   string(REPLACE "." "_" Name "${Name}")
 
-  set(_target "${GFORTRAN_PREFIX}-${Name}")
+  set(test_target "${GFORTRAN_PREFIX}-${Name}")
+  set(working_dir_name "${test_target}.wd")
+  set(working_dir "${CMAKE_CURRENT_BINARY_DIR}/${working_dir_name}")
 
+  # Several tests in the suite build modules with the same name at build-time.
+  # Others create/write/read files with the same name at test-time. In either
+  # case, these are race conditions which can lead to non-deterministic failures
+  # at build and/or test time. To work around this, have each test run in its
+  # own directory.
+  #
+  # This directory is also used as module directory at build-time.
+  #
+  # It may be "cleaner" to have separate directories - one that serves as the
+  # module directory and the other as the working directory, but that is
+  # probably unnecessary.
+  file(MAKE_DIRECTORY ${working_dir})
+
+  # Parse the dg-options annotations in the file and add it to DG_FFLAGS.
   gfortran_dg_options_fflags(DG_FFLAGS ${File})
 
-  # Add any flags that were requested
+  # Add any flags that were requested.
   list(APPEND FFLAGS ${DG_FFLAGS} ${GFORTRAN_FFLAGS})
   list(APPEND LDFLAGS ${GFORTRAN_LDFLAGS})
 
-  llvm_test_executable_no_test(${_target} ${File} ${GFORTRAN_DEPFILES})
-  llvm_test_run()
+  llvm_test_executable_no_test(${test_target} ${File} ${GFORTRAN_DEPFILES})
+  llvm_test_run(WORKDIR "%S/${working_dir_name}")
+  llvm_add_test_for_target(${test_target})
 
-  llvm_add_test_for_target(${_target})
-  target_include_directories(${_target} PRIVATE ${ISO_FORTRAN_C_HEADER_DIR})
+  target_include_directories(${test_target}
+    PRIVATE ${ISO_FORTRAN_C_HEADER_DIR} ${working_dir})
+  set_target_properties(${test_target} PROPERTIES
+    Fortran_MODULE_DIRECTORY ${working_dir})
 
   # This is a workaround because cmake does not currently recognize the .f03
   # and .f08 extensions. A patch to fix cmake has been accepted and the fix
@@ -292,8 +312,8 @@ function(gfortran_execute_test File)
 
   # NOTE: This should be removed when the -flang-experimental-exec flag is no
   # longer needed.
-  target_link_options(${_target} PRIVATE -flang-experimental-exec)
-  set_target_properties(${_target} PROPERTIES LINKER_LANGUAGE Fortran)
+  target_link_options(${test_target} PRIVATE -flang-experimental-exec)
+  set_target_properties(${test_target} PROPERTIES LINKER_LANGUAGE Fortran)
 endfunction()
 
 add_subdirectory(regression)

Fortran/gfortran/regression/CMakeLists.txt

@@ -1845,41 +1845,6 @@ file(GLOB Failing CONFIGURE_DEPENDS
   # anyway so the test-suite passes by default on AArch64.
   entry_23.f
   findloc_8.f90
-
-  # These tests have race conditions with other tests that cause them to
-  # occasionally fail when run in parallel. Every test in each group listed
-  # below has a race condition with at least one other test in the group.
-
-  # <group> Tests read/write/replace/delete file named 'tmp.dat'
-  pr88169_1.f90
-  pr88169_2.f90
-  pr88169_3.f90
-  list_read_6.f90
-  # </group>
-
-  # <group>
-  write_rewind_1.f
-  write_rewind_2.f
-  # </group>
-
-  # <group> Tests read/delete/append file named 'foo'
-  append_1.f90
-  large_unit_2.f90
-  open_access_append_1.f90
-  open_status_1.f90
-  # </group>
-
-  # <group> Tests create/replace file named 'test.dat'
-  direct_io_12.f90
-  endfile.f90
-  eof_4.f90
-  implied_do_io_1.f90
-  list_read_7.f90
-  namelist_76.f90
-  read_eof_8.f90
-  read_eof_all.f90
-  streamio_18.f90
-  # </group>
 )
 
 list(APPEND UnsupportedTests "${Unsupported}")

Fortran/gfortran/torture/execute/CMakeLists.txt

@@ -104,14 +104,6 @@ file(GLOB Skipped CONFIGURE_DEPENDS
 
   # error: '[SYM]' is not a known intrinsic procedure
   specifics.f90
-
-  # --------------------------------------------------------------------------
-  #
-  # These tests are skipped because they generate the same module as other
-  # tests in this directory and create non-deterministic conflicts when building
-  # in parallel.
-
-  module_init_1.f90  # Conflicts with function_module_1.f90
 )
 
 # These tests are disabled because they fail at runtime when they should pass.