Incorporated review comments

Author: rajkan01

tools/test/toolchains/test_toolchains.py

@@ -179,7 +179,7 @@ def test_iar_minimal_printf(self):
         self.assertIn("-DMBED_MINIMAL_PRINTF", iar_obj.flags["common"])
 
     def test_iar_default_lib(self):
-        """Test that linker flags are correctly added to an instance of IAR."""
+        """Test that case insensitive of the default_lib option works without exception."""
         mock_target = mock.MagicMock()
         mock_target.core = "Cortex-M4"
         mock_target.supported_c_libs = {"iar": ["std"]}

tools/toolchains/arm.py

@@ -39,7 +39,7 @@
 
 UARM_TOOLCHAIN_WARNING = (
     "Warning: We noticed that you are using uARM Toolchain. "
-    "We are deprecating the uARM Toolchain. "
+    "We are deprecating the use of uARM Toolchain. "
     "For more information on how to use the ARM toolchain with small C libraries, "
     "please visit https://os.mbed.com/docs/mbed-os/latest/reference/using-small-c-libraries.html"
 )
@@ -79,7 +79,10 @@ def __init__(self, target, notify=None, macros=None,
 
         self.check_c_lib_supported(target, "arm")
 
-        if getattr(target, "default_toolchain", "ARM") == "uARM" or getattr(target, "default_lib", "std") == "small":
+        if (
+            getattr(target, "default_toolchain", "ARM") == "uARM"
+            or getattr(target, "default_lib", "std") == "small"
+        ):
             if "-DMBED_RTOS_SINGLE_THREAD" not in self.flags['common']:
                 self.flags['common'].append("-DMBED_RTOS_SINGLE_THREAD")
             if "-D__MICROLIB" not in self.flags['common']:
@@ -566,7 +569,10 @@ def __init__(self, target, *args, **kwargs):
 
         self.check_c_lib_supported(target, "arm")
 
-        if getattr(target, "default_toolchain", "ARMC6") == "uARM" or getattr(target, "default_lib", "std") == "small":
+        if (
+            getattr(target, "default_toolchain", "ARMC6") == "uARM"
+            or getattr(target, "default_lib", "std") == "small"
+        ):
             if "-DMBED_RTOS_SINGLE_THREAD" not in self.flags['common']:
                 self.flags['common'].append("-DMBED_RTOS_SINGLE_THREAD")
             if "-D__MICROLIB" not in self.flags['common']:

tools/toolchains/gcc.py

@@ -54,8 +54,9 @@ def __init__(self, target,  notify=None, macros=None, build_profile=None,
             default_lib = target.default_lib
         elif hasattr(target, "default_build"):
             default_lib = target.default_build
-        else:
-            raise NotSupportedException("default_lib is an empty")
+
+        if not default_lib:
+            raise NotSupportedException("default_lib is not set")
 
         if default_lib == "small":
             common_flags = ["-DMBED_RTOS_SINGLE_THREAD", "-D__NEWLIB_NANO"]