Automatically detect source files language when invoking cppcheck

platformio/commands/check/tools/base.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import click
+import os
 
 from platformio import fs, proc
 from platformio.commands.check.defect import DefectItem
@@ -126,6 +127,16 @@ class CheckToolBase(object):  # pylint: disable=too-many-instance-attributes
             get_project_dir(), self.options.get("filter"), file_extensions
         )
 
+    def get_source_language(self):
+        with fs.cd(get_project_dir()):
+            for _, __, files in os.walk(self.config.get_optional_dir("src")):
+                for name in files:
+                    if "." not in name:
+                        continue
+                    if os.path.splitext(name)[1].lower() in (".cpp", ".cxx", ".ino"):
+                        return "c++"
+            return "c"
+
     def check(self, on_defect_callback=None):
         self._on_defect_callback = on_defect_callback
         cmd = self.configure_command()

platformio/commands/check/tools/cppcheck.py

@@ -90,6 +90,9 @@ class CppcheckCheckTool(CheckToolBase):
             % "<&PIO&>".join(["{0}={{{0}}}".format(f) for f in self.defect_fields])
         )
 
+        if self.get_source_language() == "c++":
+            cmd.append("--language=c++")
+
         flags = self.get_flags("cppcheck")
         if not self.is_flag_set("--platform", flags):
             cmd.append("--platform=unspecified")