Merge remote-tracking branch 'origin/development' into development-restricted

* origin/development: (33 commits)
  Test with MBEDTLS_ECP_RESTARTABLE
  Allow TODO in code
  Use the docstring in the command line help
  Split _abi_compliance_command into smaller functions
  Record the commits that were compared
  Document how to build the typical argument for -s
  Allow running /somewhere/else/path/to/abi_check.py
  Warn if VLAs are used
  Remove redundant compiler flag
  Consistently spell -Wextra
  Update Mbed Crypto to contain mbed-crypto#152
  Improve compatibility with firewalled networks
  Dockerfile: apt -> apt-get
  Change Docker container to bionic
  Clean up file prologue comments
  Add docker-based test scripts
  ChangeLog: Add ChangeLog entry for #2681
  Allow declarations after statements
  CMake: Add a subdirectory build regression test
  README: Enable builds as a CMake subproject
  ...

programs/Makefile

@@ -3,8 +3,8 @@
 # To compile with PKCS11: add "-lpkcs11-helper" to LDFLAGS
 
 CFLAGS	?= -O2
-WARNING_CFLAGS ?= -Wall -W -Wdeclaration-after-statement
-WARNING_CXXFLAGS ?= -Wall -W
+WARNING_CFLAGS ?= -Wall -Wextra
+WARNING_CXXFLAGS ?= -Wall -Wextra
 LDFLAGS ?=
 
 LOCAL_CFLAGS = $(WARNING_CFLAGS) -I../include -D_FILE_OFFSET_BITS=64

programs/test/cmake_subproject/.gitignore

@@ -0,0 +1,3 @@
+build
+Makefile
+cmake_subproject

programs/test/cmake_subproject/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 2.6)
+
+# We use the parent Mbed TLS directory as the MBEDTLS_DIR for this test. Other
+# projects that use Mbed TLS as a subproject are likely to add by their own
+# relative paths.
+set(MBEDTLS_DIR ../../../)
+
+# Add Mbed TLS as a subdirectory.
+add_subdirectory(${MBEDTLS_DIR} build)
+
+# Link against all the Mbed TLS libraries.
+set(libs
+    mbedtls
+    mbedcrypto
+    mbedx509
+)
+
+add_executable(cmake_subproject cmake_subproject.c)
+target_link_libraries(cmake_subproject ${libs})

programs/test/cmake_subproject/cmake_subproject.c

@@ -0,0 +1,56 @@
+/*
+ *  Simple program to test that CMake builds with Mbed TLS as a subdirectory
+ *  work correctly.
+ *
+ *  Copyright (C) 2006-2019, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_fprintf         fprintf
+#define mbedtls_printf          printf
+#define mbedtls_exit            exit
+#define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
+#endif /* MBEDTLS_PLATFORM_C */
+
+#include "mbedtls/version.h"
+
+/* The main reason to build this is for testing the CMake build, so the program
+ * doesn't need to do very much. It calls a single library function to ensure
+ * linkage works, but that is all. */
+int main()
+{
+    /* This version string is 18 bytes long, as advised by version.h. */
+    char version[18];
+
+    mbedtls_version_get_string_full( version );
+
+    mbedtls_printf( "Built against %s\n", version );
+
+    return( 0 );
+}