[core] remove dependency on libstdc++ (#3130)

configure.ac

@@ -233,7 +233,7 @@ AC_PATH_PROG(CMP, cmp)
 #
 
 PROSPECTIVE_CFLAGS="-Wall -Wextra -Wshadow -Werror -std=c99 -pedantic-errors"
-PROSPECTIVE_CXXFLAGS="-Wall -Wextra -Wshadow -Werror -std=gnu++98 -Wno-c++14-compat"
+PROSPECTIVE_CXXFLAGS="-Wall -Wextra -Wshadow -Werror -std=gnu++98 -Wno-c++14-compat -fno-exceptions -fno-rtti"
 
 AC_CACHE_CHECK([whether $CC is Clang],
     [nl_cv_clang],

examples/platforms/posix/Makefile.platform.am

@@ -32,5 +32,4 @@
 
 LDADD_COMMON                                                          += \
     $(top_builddir)/examples/platforms/posix/libopenthread-posix.a       \
-    -lstdc++                                                             \
     $(NULL)

src/cli/cli_server.hpp

@@ -54,19 +54,32 @@ public:
      *
      * @returns The number of bytes placed in the output queue.
      *
+     * @retval  -1  Driver is broken.
+     *
      */
-    virtual int Output(const char *aBuf, uint16_t aBufLength) = 0;
+    virtual int Output(const char *aBuf, uint16_t aBufLength)
+    {
+        OT_UNUSED_VARIABLE(aBuf);
+        OT_UNUSED_VARIABLE(aBufLength);
+        return -1;
+    }
 
     /**
      * This method delivers formatted output to the client.
      *
-     * @param[in]  aFmt  A pointer to the format string.
-     * @param[in]  ...   A variable list of arguments to format.
+     * @param[in]  aFormat  A pointer to the format string.
+     * @param[in]  ...      A variable list of arguments to format.
      *
      * @returns The number of bytes placed in the output queue.
      *
+     * @retval  -1  Driver is broken.
+     *
      */
-    virtual int OutputFormat(const char *fmt, ...) = 0;
+    virtual int OutputFormat(const char *aFormat, ...)
+    {
+        OT_UNUSED_VARIABLE(aFormat);
+        return -1;
+    }
 };
 
 } // namespace Cli

src/core/net/netif.hpp

@@ -408,7 +408,11 @@ public:
      * @retval OT_ERROR_NONE  Successfully enqueued the IPv6 message.
      *
      */
-    virtual otError SendMessage(Message &aMessage) = 0;
+    virtual otError SendMessage(Message &aMessage)
+    {
+        OT_UNUSED_VARIABLE(aMessage);
+        return OT_ERROR_NOT_IMPLEMENTED;
+    }
 
     /**
      * This virtual method fills out @p aAddress with the link address.
@@ -418,7 +422,11 @@ public:
      * @retval OT_ERROR_NONE  Successfully retrieved the link address.
      *
      */
-    virtual otError GetLinkAddress(LinkAddress &aAddress) const = 0;
+    virtual otError GetLinkAddress(LinkAddress &aAddress) const
+    {
+        OT_UNUSED_VARIABLE(aAddress);
+        return OT_ERROR_NOT_IMPLEMENTED;
+    }
 
     /**
      * This virtual method performs a source-destination route lookup.
@@ -431,7 +439,13 @@ public:
      * @retval OT_ERROR_NO_ROUTE  No route to destination.
      *
      */
-    virtual otError RouteLookup(const Address &aSource, const Address &aDestination, uint8_t *aPrefixMatch) = 0;
+    virtual otError RouteLookup(const Address &aSource, const Address &aDestination, uint8_t *aPrefixMatch)
+    {
+        OT_UNUSED_VARIABLE(aSource);
+        OT_UNUSED_VARIABLE(aDestination);
+        OT_UNUSED_VARIABLE(aPrefixMatch);
+        return OT_ERROR_NOT_IMPLEMENTED;
+    }
 
 private:
     NetifUnicastAddress *  mUnicastAddresses;

src/posix/Makefile.am

@@ -58,7 +58,6 @@ LIBTOOLFLAGS_COMMON = --preserve-dup-deps
 
 LDADD_COMMON                                                           = \
     $(top_builddir)/src/posix/platform/libopenthread-posix.a             \
-    -lstdc++                                                             \
     -lutil                                                               \
     $(NULL)