Enable build with IAR when c_lib is set to small

Author: hugueskamba

tools/build_api.py

@@ -48,6 +48,7 @@
 from .libraries import Library
 from .toolchains import TOOLCHAIN_CLASSES, TOOLCHAIN_PATHS
 from .toolchains.arm import UARM_TOOLCHAIN_WARNING
+from .toolchains.iar import IAR_SMALL_LIB_WARNING
 from .config import Config
 
 RELEASE_VERSIONS = ['2', '5']
@@ -250,6 +251,13 @@ def find_valid_toolchain(target, toolchain):
                 and "uARM" in {toolchain_name, target.default_toolchain}
             ):
                 end_warnings.append(UARM_TOOLCHAIN_WARNING)
+
+            if (
+                toolchain_name == "IAR"
+                and target.c_lib.lower() == "small"
+            ):
+                end_warnings.append(IAR_SMALL_LIB_WARNING)
+
             return toolchain_name, internal_tc_name, end_warnings
     else:
         if last_error:

tools/test/toolchains/test_toolchains.py

@@ -209,13 +209,16 @@ def test_iar_c_lib_std_exception(self):
         with self.assertRaisesRegexp(NotSupportedException, UNSUPPORTED_C_LIB_EXCEPTION_STRING.format(mock_target.c_lib)):
             IAR(mock_target)
 
-    def test_iar_c_lib_small_exception(self):
-        """Test that an exception is raised if the small C library is not supported for a target on the IAR toolchain."""
+    def test_iar_c_lib_small(self):
+        """Test that no exception is raised if the small C library is used with the IAR toolchain."""
         mock_target = mock.MagicMock()
         mock_target.core = "Cortex-M4"
         mock_target.c_lib = "small"
         del mock_target.default_lib
         mock_target.supported_c_libs = {"iar": ["std"]}
         mock_target.supported_toolchains = ["IAR"]
-        with self.assertRaisesRegexp(NotSupportedException, UNSUPPORTED_C_LIB_EXCEPTION_STRING.format(mock_target.c_lib)):
+        mock_target.is_TrustZone_secure_target = False
+        try:
             IAR(mock_target)
+        except NotSupportedException:
+            self.fail(UNSUPPORTED_C_LIB_EXCEPTION_STRING.format(mock_target.c_lib))

tools/toolchains/iar.py

@@ -23,6 +23,12 @@
 from tools.toolchains.mbed_toolchain import mbedToolchain, TOOLCHAIN_PATHS
 from tools.utils import run_cmd
 
+
+IAR_SMALL_LIB_WARNING = (
+    "Warning: We noticed that you are using IAR toolchain with target.c_lib set to small. "
+    "As there is no small C library for the IAR toolchain, we are using the standard C library instead. "
+)
+
 class IAR(mbedToolchain):
     OFFICIALLY_SUPPORTED = True
     LIBRARY_EXT = '.a'
@@ -54,7 +60,10 @@ def __init__(self, target, notify=None, macros=None, build_profile=None,
             build_profile=build_profile
         )
 
-        self.check_c_lib_supported(target, "iar")
+        # Build with the standard C lib if c_lib is set to small as there
+        # is no small lib for the IAR toolchain
+        if target.c_lib.lower() != "small":
+            self.check_c_lib_supported(target, "iar")
 
         if target.is_TrustZone_secure_target:
             # Enable compiler security extensions