Replace exe_exists function with shutil.which()

The documentation for subprocess.run at https://docs.python.org/3/library/subprocess.html#popen-constructor has a warning,
pointing to using shutil.which() instead of subprocess.run for detecting if exe files exists on the path.

shutil.which() is used in many places already.

mesonbuild/environment.py

@@ -109,13 +109,13 @@ def detect_llvm_cov(suffix: T.Optional[str] = None):
             tool = 'llvm-cov'
         else:
             tool = f'llvm-cov-{suffix}'
-        if mesonlib.exe_exists([tool, '--version']):
+        if shutil.which(tool) is not None:
             return tool
     else:
         # Otherwise guess in the dark
         tools = get_llvm_tool_names('llvm-cov')
         for tool in tools:
-            if mesonlib.exe_exists([tool, '--version']):
+            if shutil.which(tool):
                 return tool
     return None
 
@@ -139,7 +139,7 @@ def compute_llvm_suffix(coredata: coredata.CoreData):
 
 def detect_lcov_genhtml(lcov_exe: str = 'lcov', genhtml_exe: str = 'genhtml'):
     lcov_exe, lcov_version = detect_lcov(lcov_exe)
-    if not mesonlib.exe_exists([genhtml_exe, '--version']):
+    if shutil.which(genhtml_exe) is None:
         genhtml_exe = None
 
     return lcov_exe, lcov_version, genhtml_exe

mesonbuild/scripts/coverage.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 
 from mesonbuild import environment, mesonlib
 
-import argparse, re, sys, os, subprocess, pathlib, stat
+import argparse, re, sys, os, subprocess, pathlib, stat, shutil
 import typing as T
 
 def coverage(outputs: T.List[str], source_root: str, subproject_root: str, build_root: str, log_dir: str, use_llvm_cov: bool,
@@ -17,7 +17,7 @@ def coverage(outputs: T.List[str], source_root: str, subproject_root: str, build
         gcovr_exe = None
     else:
         gcovr_exe, gcovr_version = environment.detect_gcovr(gcovr_exe)
-    if llvm_cov_exe == '' or not mesonlib.exe_exists([llvm_cov_exe, '--version']):
+    if llvm_cov_exe == '' or shutil.which(llvm_cov_exe) is None:
         llvm_cov_exe = None
 
     lcov_exe, lcov_version, genhtml_exe = environment.detect_lcov_genhtml()

mesonbuild/utils/universal.py

@@ -98,7 +98,6 @@ __all__ = [
     'do_conf_file',
     'do_conf_str',
     'do_replacement',
-    'exe_exists',
     'expand_arguments',
     'extract_as_list',
     'first',
@@ -683,14 +682,8 @@ def is_qnx() -> bool:
 def is_aix() -> bool:
     return platform.system().lower() == 'aix'
 
-def exe_exists(arglist: T.List[str]) -> bool:
-    try:
-        if subprocess.run(arglist, timeout=10).returncode == 0:
-            return True
-    except (FileNotFoundError, subprocess.TimeoutExpired):
-        pass
-    return False
-
+def exe_exists(exe: str) -> bool:
+    return shutil.which(exe) is not None
 
 @lru_cache(maxsize=None)
 def darwin_get_object_archs(objpath: str) -> 'ImmutableListProtocol[str]':

unittests/internaltests.py

@@ -39,6 +39,7 @@ from mesonbuild.interpreter.type_checking import in_set_validator, NoneType
 from mesonbuild.dependencies.pkgconfig import PkgConfigDependency, PkgConfigInterface, PkgConfigCLI
 from mesonbuild.programs import ExternalProgram
 import mesonbuild.modules.pkgconfig
+from mesonbuild import utils
 
 
 from run_tests import (
@@ -813,6 +814,10 @@ class InternalTests(unittest.TestCase):
         self.assertTrue(vctools_ver.startswith(toolset_ver),
                         msg=f'{vctools_ver!r} does not start with {toolset_ver!r}')
 
+    def test_exe_exists(self):
+        self.assertTrue(utils.universal.exe_exists('python3'))
+        self.assertFalse(utils.universal.exe_exists('command_that_does_not_exist'))
+
     def test_split_args(self):
         split_args = mesonbuild.mesonlib.split_args
         join_args = mesonbuild.mesonlib.join_args