Fortran 2008 submodule (#4874)

9 files changed, 131 insertions, 7 deletions

diff --git a/docs/markdown/snippets/fortran_submodule.md b/docs/markdown/snippets/fortran_submodule.md
new file mode 100644
index 0000000..9e4b9cc
--- /dev/null
+++ b/docs/markdown/snippets/fortran_submodule.md
@@ -0,0 +1,12 @@
+## Fortran submodule support
+
+Initial support for Fortran ``submodule`` was added, where the submodule is in
+the same or different file than the parent ``module``.
+The submodule hierarchy specified in the source Fortran code `submodule`
+statements are used by Meson to resolve source file dependencies.
+For example:
+
+```fortran
+submodule (ancestor:parent) child
+```
+
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 87f9b38..463e999 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+from typing import List
 import os
 import re
 import shlex
@@ -29,7 +29,7 @@ from .. import build
 from .. import mlog
 from .. import dependencies
 from .. import compilers
-from ..compilers import CompilerArgs, CCompiler, VisualStudioCCompiler
+from ..compilers import CompilerArgs, CCompiler, VisualStudioCCompiler, FortranCompiler
 from ..linkers import ArLinker
 from ..mesonlib import File, MachineChoice, MesonException, OrderedSet
 from ..mesonlib import get_compiler_for_source, has_path_sep
@@ -1826,7 +1826,8 @@ rule FORTRAN_DEP_HACK%s
         if compiler is None:
             self.fortran_deps[target.get_basename()] = {}
             return
-        modre = re.compile(r"\bmodule\s+(\w+)\s*$", re.IGNORECASE)
+        modre = re.compile(r"\s*\bmodule\b\s+(\w+)\s*$", re.IGNORECASE)
+        submodre = re.compile(r"\s*\bsubmodule\b\s+\((\w+:?\w+)\)\s+(\w+)\s*$", re.IGNORECASE)
         module_files = {}
         for s in target.get_sources():
             # FIXME, does not work for Fortran sources generated by
@@ -1849,11 +1850,23 @@ rule FORTRAN_DEP_HACK%s
                                 'two files %s and %s.' %
                                 (modname, module_files[modname], s))
                         module_files[modname] = s
+                    else:
+                        submodmatch = submodre.match(line)
+                        if submodmatch is not None:
+                            submodname = submodmatch.group(2).lower()
+                            if submodname in module_files:
+                                raise InvalidArguments(
+                                    'Namespace collision: submodule %s defined in '
+                                    'two files %s and %s.' %
+                                    (submodname, module_files[submodname], s))
+                            module_files[submodname] = s
+
         self.fortran_deps[target.get_basename()] = module_files
 
-    def get_fortran_deps(self, compiler, src, target):
+    def get_fortran_deps(self, compiler: FortranCompiler, src: str, target) -> List[str]:
         mod_files = []
         usere = re.compile(r"\s*use\s+(\w+)", re.IGNORECASE)
+        submodre = re.compile(r"\s*\bsubmodule\b\s+\((\w+:?\w+)\)\s+(\w+)\s*$", re.IGNORECASE)
         dirname = self.get_target_private_dir(target)
         tdeps = self.fortran_deps[target.get_basename()]
         with open(src) as f:
@@ -1879,9 +1892,23 @@ rule FORTRAN_DEP_HACK%s
                     # the same name.
                     if mod_source_file.fname == os.path.basename(src):
                         continue
-                    mod_name = compiler.module_name_to_filename(
-                        usematch.group(1))
+                    mod_name = compiler.module_name_to_filename(usename)
                     mod_files.append(os.path.join(dirname, mod_name))
+                else:
+                    submodmatch = submodre.match(line)
+                    if submodmatch is not None:
+                        parents = submodmatch.group(1).lower().split(':')
+                        assert len(parents) in (1, 2), (
+                            'submodule ancestry must be specified as'
+                            ' ancestor:parent but Meson found {}'.parents)
+                        for parent in parents:
+                            if parent not in tdeps:
+                                raise MesonException("submodule {} relies on parent module {} that was not found.".format(submodmatch.group(2).lower(), parent))
+                            if tdeps[parent].fname == os.path.basename(src):  # same file
+                                continue
+                            mod_name = compiler.module_name_to_filename(parent)
+                            mod_files.append(os.path.join(dirname, mod_name))
+
         return mod_files
 
     def get_cross_stdlib_args(self, target, compiler):
diff --git a/mesonbuild/compilers/fortran.py b/mesonbuild/compilers/fortran.py
index eea1660..8c50736 100644
--- a/mesonbuild/compilers/fortran.py
+++ b/mesonbuild/compilers/fortran.py
@@ -179,7 +179,7 @@ class FortranCompiler(Compiler):
 
         return parameter_list
 
-    def module_name_to_filename(self, module_name):
+    def module_name_to_filename(self, module_name: str) -> str:
         return module_name.lower() + '.mod'
 
     def get_std_shared_lib_link_args(self):
diff --git a/test cases/fortran/12 submodule/a1.f90 b/test cases/fortran/12 submodule/a1.f90
new file mode 100644
index 0000000..cb44916
--- /dev/null
+++ b/test cases/fortran/12 submodule/a1.f90
@@ -0,0 +1,25 @@
+module a1
+implicit none
+
+interface
+module elemental real function pi2tau(pi)
+  real, intent(in) :: pi
+end function pi2tau
+
+module real function get_pi()
+end function get_pi
+end interface
+
+end module a1
+
+program hierN
+
+use a1
+
+pi = get_pi()
+
+tau = pi2tau(pi)
+
+print *,'pi=',pi,'tau=',tau
+
+end program
diff --git a/test cases/fortran/12 submodule/a2.f90 b/test cases/fortran/12 submodule/a2.f90
new file mode 100644
index 0000000..b3ce1f0
--- /dev/null
+++ b/test cases/fortran/12 submodule/a2.f90
@@ -0,0 +1,10 @@
+submodule (a1) a2
+
+contains
+
+module procedure pi2tau
+  pi2tau = 2*pi
+end procedure pi2tau
+
+
+end submodule a2
diff --git a/test cases/fortran/12 submodule/a3.f90 b/test cases/fortran/12 submodule/a3.f90
new file mode 100644
index 0000000..d6929b0
--- /dev/null
+++ b/test cases/fortran/12 submodule/a3.f90
@@ -0,0 +1,10 @@
+submodule (a1:a2) a3
+
+contains
+
+module procedure get_pi
+  get_pi = 4.*atan(1.)
+end procedure get_pi
+
+
+end submodule a3
diff --git a/test cases/fortran/12 submodule/child.f90 b/test cases/fortran/12 submodule/child.f90
new file mode 100644
index 0000000..aa5bb5e
--- /dev/null
+++ b/test cases/fortran/12 submodule/child.f90
@@ -0,0 +1,10 @@
+submodule (mother) daughter
+
+contains
+
+module procedure pi2tau
+  pi2tau = 2*pi
+end procedure pi2tau
+
+end submodule daughter
+
diff --git a/test cases/fortran/12 submodule/meson.build b/test cases/fortran/12 submodule/meson.build
new file mode 100644
index 0000000..cd62a30
--- /dev/null
+++ b/test cases/fortran/12 submodule/meson.build
@@ -0,0 +1,7 @@
+project('submodule single level', 'fortran')
+
+hier2 = executable('single', 'parent.f90','child.f90')
+test('single-level hierarchy', hier2)
+
+hierN = executable('multi', 'a1.f90', 'a2.f90', 'a3.f90')
+test('multi-level hierarchy', hierN)
diff --git a/test cases/fortran/12 submodule/parent.f90 b/test cases/fortran/12 submodule/parent.f90
new file mode 100644
index 0000000..05fe431
--- /dev/null
+++ b/test cases/fortran/12 submodule/parent.f90
@@ -0,0 +1,23 @@
+module mother
+real, parameter :: pi = 4.*atan(1.)
+real :: tau
+
+interface
+module elemental real function pi2tau(pi)
+  real, intent(in) :: pi
+end function pi2tau
+end interface
+
+contains 
+
+end module mother
+
+
+program hier1
+use mother
+
+tau = pi2tau(pi)
+
+print *,'pi=',pi, 'tau=', tau
+
+end program