BUG: Handle --f77flags and --f90flags for meson [wheel build]

Backport of #26703, #26706, and #26812. Closes #25784. Background and notes: - Although the CLI was passing `fc_flags` to the Meson backend they weren't being used - The behavior currently is to (redundantly) collect the unique set of flags passed via either `--f77flags` or `--f90flags` - They all map to `fortran_args` for the `meson.build` (`distutils` used to have separate handling for the two cases) - Eventually these should be merged into a single `--fflags` argument (basically since they're now redundant post-distutils) - This is likely only when we have 3.12 as the lowest supported version, since `distutils` will need to have both CLI options - The test is specially crafted to get an error without `-ffixed-form` but is otherwise junk - Adding a continuation character at the end of the line as well will both get `f2py` and `gfortran` to compile without `-ffixed-form` - Or putting the same code in a `.f` file, thereby signalling to F2PY that this is a Fortran 77 file It does make sense to handle `fortran_args` this way though, since it is more robust than setting `FFLAGS` (which anyway won't work due to a `meson` bug, mesonbuild/meson#13327). Squashed commit of the following: commit bbc198b48b79417f210bd38de6c60ab98d18857d Author: Rohit Goswami <rog32@hi.is> Date: Fri Jun 28 19:43:41 2024 +0200 CI,MAINT: Bump gfortran version [wheel build] Co-authored-by: ngoldbaum <ngoldbaum@users.noreply.github.com> commit fffa296b7a611de1ab25f85619e92e6d6c5185a4 Author: Rohit Goswami <rog32@hi.is> Date: Fri Jun 28 14:54:50 2024 +0200 CI,TST: Fix meson tests needing gfortran [wheel build] commit 807e898e80e544e720512f9feccc9c897cd55f08 Author: Rohit Goswami <rog32@hi.is> Date: Sun Jun 16 09:40:06 2024 +0000 TST: Skip an f2py module test on Windows commit cbcb6c2c4340f5bbca46e2c6d8474bbed7d90664 Author: Rohit Goswami <rog32@hi.is> Date: Sun Jun 16 04:06:16 2024 +0000 MAINT: Be more robust wrt f2py flags commit 09e3eb004b0e076271817384a92d489b3b0cc0eb Author: Rohit Goswami <rog32@hi.is> Date: Sun Jun 16 03:44:17 2024 +0000 TST: Add one for passing arguments to f2py Co-authored-by: warrickball <warrickball@users.noreply.github.com> commit 04d53b44b75537fc5b411cf9e54c2f169198419f Author: Rohit Goswami <rog32@hi.is> Date: Sun Jun 16 00:14:54 2024 +0000 BUG: Use fortran args from f2py in meson commit 6f736b0cbe977ba9270c45f7cc22b7ae8ce06ed2 Author: Rohit Goswami <rog32@hi.is> Date: Sat Jun 15 23:36:55 2024 +0000 MAINT,BUG: Correctly skip distutils options
numpy · charris · Jul 5, 2024 · Jul 5, 2024 · Jul 5, 2024 · 526a2f45e4ffd0a000c10fcdf7a21786e40ac0d7
commit 526a2f45e4ffd0a000c10fcdf7a21786e40ac0d7
diff --git a/.github/workflows/wheels.yml b/.github/workflows/wheels.yml
@@ -130,6 +130,11 @@ jobs:
       - name: Setup macOS
         if: matrix.buildplat[0] == 'macos-13' || matrix.buildplat[0] == 'macos-14'
         run: |
+          # Needed due to https://github.com/actions/runner-images/issues/3371
+          # Supported versions: https://github.com/actions/runner-images/blob/main/images/macos/macos-14-arm64-Readme.md
+          echo "FC=gfortran-13" >> "$GITHUB_ENV"
+          echo "F77=gfortran-13" >> "$GITHUB_ENV"
+          echo "F90=gfortran-13" >> "$GITHUB_ENV"
           if [[ ${{ matrix.buildplat[2] }} == 'accelerate' ]]; then
             # macosx_arm64 and macosx_x86_64 with accelerate
             # only target Sonoma onwards

diff --git a/numpy/f2py/_backends/_meson.py b/numpy/f2py/_backends/_meson.py
@@ -28,7 +28,7 @@ def __init__(
         include_dirs: list[Path],
         object_files: list[Path],
         linker_args: list[str],
-        c_args: list[str],
+        fortran_args: list[str],
         build_type: str,
         python_exe: str,
     ):
@@ -46,12 +46,18 @@ def __init__(
             self.include_dirs = []
         self.substitutions = {}
         self.objects = object_files
+        # Convert args to '' wrapped variant for meson
+        self.fortran_args = [
+            f"'{x}'" if not (x.startswith("'") and x.endswith("'")) else x
+            for x in fortran_args
+        ]
         self.pipeline = [
             self.initialize_template,
             self.sources_substitution,
             self.deps_substitution,
             self.include_substitution,
             self.libraries_substitution,
+            self.fortran_args_substitution,
         ]
         self.build_type = build_type
         self.python_exe = python_exe
@@ -109,6 +115,14 @@ def include_substitution(self) -> None:
             [f"{self.indent}'''{inc}'''," for inc in self.include_dirs]
         )
 
+    def fortran_args_substitution(self) -> None:
+        if self.fortran_args:
+            self.substitutions["fortran_args"] = (
+                f"{self.indent}fortran_args: [{', '.join([arg for arg in self.fortran_args])}],"
+            )
+        else:
+            self.substitutions["fortran_args"] = ""
+
     def generate_meson_build(self):
         for node in self.pipeline:
             node()
@@ -126,6 +140,7 @@ def __init__(self, *args, **kwargs):
         self.build_type = (
             "debug" if any("debug" in flag for flag in self.fc_flags) else "release"
         )
+        self.fc_flags = _get_flags(self.fc_flags)
 
     def _move_exec_to_root(self, build_dir: Path):
         walk_dir = Path(build_dir) / self.meson_build_dir
@@ -203,3 +218,17 @@ def _prepare_sources(mname, sources, bdir):
         if not Path(source).suffix == ".pyf"
     ]
     return extended_sources
+
+
+def _get_flags(fc_flags):
+    flag_values = []
+    flag_pattern = re.compile(r"--f(77|90)flags=(.*)")
+    for flag in fc_flags:
+        match_result = flag_pattern.match(flag)
+        if match_result:
+            values = match_result.group(2).strip().split()
+            values = [val.strip("'\"") for val in values]
+            flag_values.extend(values)
+    # Hacky way to preserve order of flags
+    unique_flags = list(dict.fromkeys(flag_values))
+    return unique_flags
diff --git a/numpy/f2py/_backends/meson.build.template b/numpy/f2py/_backends/meson.build.template
@@ -51,4 +51,5 @@ ${dep_list}
 ${lib_list}
 ${lib_dir_list}
                      ],
+${fortran_args}
                      install : true)
diff --git a/numpy/f2py/f2py2e.py b/numpy/f2py/f2py2e.py
@@ -635,10 +635,14 @@ def run_compile():
         r'--((f(90)?compiler(-exec|)|compiler)=|help-compiler)')
     flib_flags = [_m for _m in sys.argv[1:] if _reg3.match(_m)]
     sys.argv = [_m for _m in sys.argv if _m not in flib_flags]
-    _reg4 = re.compile(
-        r'--((f(77|90)(flags|exec)|opt|arch)=|(debug|noopt|noarch|help-fcompiler))')
-    fc_flags = [_m for _m in sys.argv[1:] if _reg4.match(_m)]
-    sys.argv = [_m for _m in sys.argv if _m not in fc_flags]
+    # TODO: Once distutils is dropped completely, i.e. min_ver >= 3.12, unify into --fflags
+    reg_f77_f90_flags = re.compile(r'--f(77|90)flags=')
+    reg_distutils_flags = re.compile(r'--((f(77|90)exec|opt|arch)=|(debug|noopt|noarch|help-fcompiler))')
+    fc_flags = [_m for _m in sys.argv[1:] if reg_f77_f90_flags.match(_m)]
+    distutils_flags = [_m for _m in sys.argv[1:] if reg_distutils_flags.match(_m)]
+    if not (MESON_ONLY_VER or backend_key == 'meson'):
+        fc_flags.extend(distutils_flags)
+    sys.argv = [_m for _m in sys.argv if _m not in (fc_flags + distutils_flags)]
 
     del_list = []
     for s in flib_flags:

diff --git a/numpy/f2py/tests/src/regression/f77fixedform.f95 b/numpy/f2py/tests/src/regression/f77fixedform.f95
@@ -0,0 +1,5 @@
+C This is an invalid file, but it does compile with -ffixed-form
+      subroutine mwe(
+     & x)
+          real x
+      end subroutine mwe
diff --git a/numpy/f2py/tests/test_regression.py b/numpy/f2py/tests/test_regression.py
@@ -1,5 +1,6 @@
 import os
 import pytest
+import platform
 
 import numpy as np
 import numpy.testing as npt
@@ -109,6 +110,7 @@ def test_gh26148b(self):
         assert(res[0] == 8)
         assert(res[1] == 15)
 
+@pytest.mark.slow
 def test_gh26623():
     # Including libraries with . should not generate an incorrect meson.build
     try:
@@ -119,3 +121,21 @@ def test_gh26623():
         )
     except RuntimeError as rerr:
         assert "lparen got assign" not in str(rerr)
+
+
+@pytest.mark.slow
+@pytest.mark.skipif(platform.system() not in ['Linux', 'Darwin'], reason='Unsupported on this platform for now')
+def test_gh25784():
+    # Compile dubious file using passed flags
+    try:
+        aa = util.build_module(
+            [util.getpath("tests", "src", "regression", "f77fixedform.f95")],
+            options=[
+                # Meson will collect and dedup these to pass to fortran_args:
+                "--f77flags='-ffixed-form -O2'",
+                "--f90flags=\"-ffixed-form -Og\"",
+            ],
+            module_name="Blah",
+        )
+    except ImportError as rerr:
+        assert "unknown_subroutine_" in str(rerr)
diff --git a/numpy/f2py/tests/util.py b/numpy/f2py/tests/util.py
@@ -121,7 +121,7 @@ def build_module(source_files, options=[], skip=[], only=[], module_name=None):
         dst_sources.append(dst)
 
         base, ext = os.path.splitext(dst)
-        if ext in (".f90", ".f", ".c", ".pyf"):
+        if ext in (".f90", ".f95", ".f", ".c", ".pyf"):
             f2py_sources.append(dst)
 
     assert f2py_sources