detect msvc and version when CC/CXX point to cl.exe (#14364)

* add test_profile_new_msvc_vcvars

* detect msvc version from cl.exe

conans/client/conf/detect.py

@@ -34,6 +34,25 @@ def _gcc_compiler(compiler_exe="gcc"):
             return compiler, installed_version
     except Exception:
         return None
+
+def _msvc_cl_compiler(compiler_exe="cl"):
+    try:
+        compiler_exe = compiler_exe.strip('"')
+        ret, out = detect_runner(f'"{compiler_exe}" /?')
+        if ret != 0:
+            return None
+        first_line = out.splitlines()[0]
+        if not "Microsoft" in first_line:
+            return None
+        compiler = "msvc"
+        version_regex = re.search(r"(?P<major>[0-9]+)\.(?P<minor>[0-9]+)\.([0-9]+)\.?([0-9]+)?", first_line)
+        if not version_regex:
+            return None
+        # 19.36.32535 -> 193
+        version = f"{version_regex.group('major')}{version_regex.group('minor')[0]}"
+        return (compiler, version)
+    except Exception:
+        return None
 
 
 def _clang_compiler(compiler_exe="clang"):
@@ -96,6 +115,9 @@ def _get_default_compiler():
             return gcc
         if platform.system() == "SunOS" and command.lower() == "cc":
             return _sun_cc_compiler(command)
+        if platform.system() == "Windows" and command.rstrip('"').endswith(("cl", "cl.exe")) and not "clang" in command:
+            return _msvc_cl_compiler(command)
+
         # I am not able to find its version
         output.error("Not able to automatically detect '%s' version" % command)
         return None

conans/test/functional/command/profile_test.py

@@ -12,7 +12,7 @@
 from conans.util.env import environment_update
 from conans.util.files import save
 from conans.util.runners import check_output_runner
-
+from conan.tools.microsoft.visual import vcvars_command
 
 class TestProfile(unittest.TestCase):
 
@@ -128,3 +128,26 @@ def test_profile_new(self):
         assert "MyProfile2' already exists" in c.out
 
         c.run("profile detect --name=./MyProfile2 --force")  # will not raise error
+
+    @pytest.mark.skipif(platform.system() != "Windows", reason="Requires Windows and msvc")
+    def test_profile_new_msvc_vcvars(self):
+        c = TestClient()
+
+        # extract location of cl.exe from vcvars
+        vcvars = vcvars_command(version="15", architecture="x64")
+        ret = c.run_command(f"{vcvars} && where cl.exe")
+        assert ret == 0
+        cl_executable = c.out.splitlines()[-1]
+        assert os.path.isfile(cl_executable)
+        cl_location = os.path.dirname(cl_executable)
+
+        # Try different variations, including full path and full path with quotes 
+        for var in ["cl", "cl.exe", cl_executable, f'"{cl_executable}"']:
+            output = RedirectedTestOutput()
+            with redirect_output(output):
+                with environment_update({"CC": var, "PATH": cl_location}):
+                    c.run("profile detect --name=./cl-profile --force")
+
+            profile = c.load("cl-profile")
+            assert "compiler=msvc" in profile
+            assert "compiler.version=191" in profile