Fix strict null typing issues in symbol extractor script

.mypy.ini

@@ -75,5 +75,8 @@ strict_optional               = True
 [mypy-mesonbuild.programs]
 strict_optional               = True
 
+[mypy-mesonbuild.scripts.symbolextractor]
+strict_optional               = True
+
 [mypy-mesonbuild.tooldetect]
 strict_optional               = True

mesonbuild/scripts/symbolextractor.py

@@ -17,11 +17,14 @@
 from ..mesonlib import Popen_safe
 import argparse
 
-parser = argparse.ArgumentParser()
+if T.TYPE_CHECKING:
+    class Arguments(T.Protocol):
 
-parser.add_argument('--cross-host', default=None, dest='cross_host',
-                    help='cross compilation host platform')
-parser.add_argument('args', nargs='+')
+        cross_host: str | None
+        builddir: str
+        libfilename: str
+        impfilename: str
+        outfilename: str
 
 TOOL_WARNING_FILE: str
 RELINKING_WARNING = 'Relinking will always happen on source changes.'
@@ -60,7 +63,7 @@ def get_tool(name: str) -> T.List[str]:
         return shlex.split(os.environ[evar])
     return [name]
 
-def call_tool(name: str, args: T.List[str], **kwargs: T.Any) -> str:
+def call_tool(name: str, args: T.List[str], **kwargs: T.Any) -> str | None:
     tool = get_tool(name)
     try:
         p, output, e = Popen_safe(tool + args, **kwargs)
@@ -75,7 +78,7 @@ def call_tool(name: str, args: T.List[str], **kwargs: T.Any) -> str:
         return None
     return output
 
-def call_tool_nowarn(tool: T.List[str], **kwargs: T.Any) -> T.Tuple[str, str]:
+def call_tool_nowarn(tool: T.List[str], **kwargs: T.Any) -> T.Tuple[str | None, str | None]:
     try:
         p, output, e = Popen_safe(tool, **kwargs)
     except FileNotFoundError:
@@ -198,7 +201,7 @@ def cygwin_syms(impfilename: str, outfilename: str) -> None:
         result.append(line.split(maxsplit=1)[0])
     write_if_changed('\n'.join(result) + '\n', outfilename)
 
-def _get_implib_dllname(impfilename: str) -> T.Tuple[T.List[str], str]:
+def _get_implib_dllname(impfilename: str) -> T.Tuple[T.List[str], str | None]:
     all_stderr = ''
     # First try lib.exe, which is provided by MSVC. Then llvm-lib.exe, by LLVM
     # for clang-cl.
@@ -214,15 +217,17 @@ def _get_implib_dllname(impfilename: str) -> T.Tuple[T.List[str], str]:
             # a single DLL, so we can pick any of these. Pick the last one for
             # simplicity. Also skip the last line, which is empty.
             return output.split('\n')[-2:-1], None
-        all_stderr += e
+        if e:
+            all_stderr += e
     # Next, try dlltool.exe which is provided by MinGW
     output, e = call_tool_nowarn(get_tool('dlltool') + ['-I', impfilename])
     if output:
         return [output], None
-    all_stderr += e
+    if e:
+        all_stderr += e
     return ([], all_stderr)
 
-def _get_implib_exports(impfilename: str) -> T.Tuple[T.List[str], str]:
+def _get_implib_exports(impfilename: str) -> T.Tuple[T.List[str], str | None]:
     all_stderr = ''
     # Force dumpbin.exe to use en-US so we can parse its output
     env = os.environ.copy()
@@ -233,7 +238,8 @@ def _get_implib_exports(impfilename: str) -> T.Tuple[T.List[str], str]:
         start = lines.index('File Type: LIBRARY')
         end = lines.index('  Summary')
         return lines[start:end], None
-    all_stderr += e
+    if e:
+        all_stderr += e
     # Next, try llvm-nm.exe provided by LLVM, then nm.exe provided by MinGW
     for nm in ('llvm-nm', 'nm'):
         output, e = call_tool_nowarn(get_tool(nm) + ['--extern-only', '--defined-only',
@@ -245,7 +251,8 @@ def _get_implib_exports(impfilename: str) -> T.Tuple[T.List[str], str]:
                     continue
                 result.append(line.split(maxsplit=1)[0])
             return result, None
-        all_stderr += e
+        if e:
+            all_stderr += e
     return ([], all_stderr)
 
 def windows_syms(impfilename: str, outfilename: str) -> None:
@@ -285,69 +292,71 @@ def os2_syms(impfilename: str, outfilename: str) -> None:
         all_stderr += e
     print_tool_warning(['nm', 'listomf'], 'do not work or were not found', all_stderr)
 
-def gen_symbols(libfilename: str, impfilename: str, outfilename: str, cross_host: str) -> None:
-    if cross_host is not None:
+def gen_symbols(options: Arguments) -> None:
+    if options.cross_host is not None:
         # In case of cross builds just always relink. In theory we could
         # determine the correct toolset, but we would need to use the correct
         # `nm`, `readelf`, etc, from the cross info which requires refactoring.
-        if cross_host == 'windows' and os.path.isfile(impfilename):
-            windows_syms(impfilename, outfilename)
+        if options.cross_host == 'windows' and os.path.isfile(options.impfilename):
+            windows_syms(options.impfilename, options.outfilename)
         else:
-            dummy_syms(outfilename)
+            dummy_syms(options.outfilename)
     elif mesonlib.is_linux() or mesonlib.is_hurd() or mesonlib.is_haiku():
-        gnu_syms(libfilename, outfilename)
+        gnu_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_osx():
-        osx_syms(libfilename, outfilename)
+        osx_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_openbsd():
-        openbsd_syms(libfilename, outfilename)
+        openbsd_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_freebsd():
-        freebsd_syms(libfilename, outfilename)
+        freebsd_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_netbsd():
-        freebsd_syms(libfilename, outfilename)
+        freebsd_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_windows():
-        if os.path.isfile(impfilename):
-            windows_syms(impfilename, outfilename)
+        if os.path.isfile(options.impfilename):
+            windows_syms(options.impfilename, options.outfilename)
         else:
             # No import library. Not sure how the DLL is being used, so just
             # rebuild everything that links to it every time.
-            dummy_syms(outfilename)
+            dummy_syms(options.outfilename)
     elif mesonlib.is_cygwin():
-        if os.path.isfile(impfilename):
-            cygwin_syms(impfilename, outfilename)
+        if os.path.isfile(options.impfilename):
+            cygwin_syms(options.impfilename, options.outfilename)
         else:
             # No import library. Not sure how the DLL is being used, so just
             # rebuild everything that links to it every time.
-            dummy_syms(outfilename)
+            dummy_syms(options.outfilename)
     elif mesonlib.is_sunos():
-        solaris_syms(libfilename, outfilename)
+        solaris_syms(options.libfilename, options.outfilename)
     elif mesonlib.is_os2():
-        if os.path.isfile(impfilename):
-            os2_syms(impfilename, outfilename)
+        if os.path.isfile(options.impfilename):
+            os2_syms(options.impfilename, options.outfilename)
         else:
             # No import library. Not sure how the DLL is being used, so just
             # rebuild everything that links to it every time.
-            dummy_syms(outfilename)
+            dummy_syms(options.outfilename)
     else:
         if not os.path.exists(TOOL_WARNING_FILE):
             mlog.warning('Symbol extracting has not been implemented for this '
                          'platform. ' + RELINKING_WARNING)
             # Write it out so we don't warn again
             with open(TOOL_WARNING_FILE, 'w', encoding='utf-8'):
                 pass
-        dummy_syms(outfilename)
+        dummy_syms(options.outfilename)
 
 def run(args: T.List[str]) -> int:
     global TOOL_WARNING_FILE  # pylint: disable=global-statement
-    options = parser.parse_args(args)
-    if len(options.args) != 4:
-        print('symbolextractor.py <shared library file> <import library> <output file>')
-        sys.exit(1)
-    privdir = os.path.join(options.args[0], 'meson-private')
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--cross-host', default=None, dest='cross_host',
+                        help='cross compilation host platform')
+    parser.add_argument('builddir', metavar='build directory')
+    parser.add_argument('libfilename', metavar='shared library')
+    parser.add_argument('impfilename', metavar='import library')
+    parser.add_argument('outfilename', metavar='output')
+    options = T.cast('Arguments', parser.parse_args(args))
+    privdir = os.path.join(options.builddir, 'meson-private')
     TOOL_WARNING_FILE = os.path.join(privdir, 'symbolextractor_tool_warning_printed')
-    libfile = options.args[1]
-    impfile = options.args[2] # Only used on Windows
-    outfile = options.args[3]
-    gen_symbols(libfile, impfile, outfile, options.cross_host)
+    gen_symbols(options)
     return 0
 
 if __name__ == '__main__':