Fixed a “TypeError” issue when extending configuration option in “platformio.ini” with the multi-line default value // Resolve #4082

HISTORY.rst

@@ -12,6 +12,8 @@ PlatformIO Core 5
 ~~~~~~~~~~~~~~~~~~
 
 - Override debugging firmware loading mode using ``--load-mode`` option for `pio debug <https://docs.platformio.org/en/latest/core/userguide/cmd_debug.html>`__ command
+- Removed debugging "legacy Click" message from CLI (`issue #4083 <https://github.com/platformio/platformio-core/issues/4083>`_)
+- Fixed a "TypeError: sequence item 1: expected str instance, list found" issue when extending configuration option in `"platformio.ini" <https://docs.platformio.org/page/projectconf.html>`__ with the multi-line default value (`issue #4082 <https://github.com/platformio/platformio-core/issues/4082>`_)
 
 5.2.1 (2021-10-11)
 ~~~~~~~~~~~~~~~~~~

platformio/project/config.py

@@ -295,7 +295,10 @@ class ProjectConfigBase(object):
         section, option = match.group(1), match.group(2)
         if section == "sysenv":
             return os.getenv(option)
-        return self.getraw(section, option)
+        value = self.getraw(section, option)
+        if isinstance(value, list):
+            return "\n".join(value)
+        return value
 
     def get(self, section, option, default=MISSING):
         value = None

tests/test_projectconf.py

@@ -63,6 +63,10 @@ targets =
 [env:test_extends]
 extends = strict_settings
 
+[env:inject_base_env]
+debug_build_flags =
+    ${env.debug_build_flags}
+    -D CUSTOM_DEBUG_FLAG
 
 """
 
@@ -150,13 +154,20 @@ def test_sections(config):
         "custom",
         "env:base",
         "env:test_extends",
+        "env:inject_base_env",
         "env:extra_1",
         "env:extra_2",
     ]
 
 
 def test_envs(config):
-    assert config.envs() == ["base", "test_extends", "extra_1", "extra_2"]
+    assert config.envs() == [
+        "base",
+        "test_extends",
+        "inject_base_env",
+        "extra_1",
+        "extra_2",
+    ]
     assert config.default_envs() == ["base", "extra_2"]
 
 
@@ -274,6 +285,14 @@ def test_get_value(config):
     assert config.get("env:extra_2", "monitor_speed") == 9600
     assert config.get("env:base", "build_flags") == ["-D DEBUG=1"]
 
+    # get default value from ConfigOption
+    assert config.get("env:inject_base_env", "debug_build_flags") == [
+        "-Og",
+        "-g2",
+        "-ggdb2",
+        "-D CUSTOM_DEBUG_FLAG",
+    ]
+
 
 def test_items(config):
     assert config.items("custom") == [
@@ -445,4 +464,13 @@ def test_dump(tmpdir_factory):
             ],
         ),
         ("env:test_extends", [("extends", ["strict_settings"])]),
+        (
+            "env:inject_base_env",
+            [
+                (
+                    "debug_build_flags",
+                    ["${env.debug_build_flags}", "-D CUSTOM_DEBUG_FLAG"],
+                )
+            ],
+        ),
     ]