diff --git a/gcc-103-substitution-bug-fix.patch b/gcc-103-substitution-bug-fix.patch
new file mode 100644
index 00000000000..9059d07b1e1
--- /dev/null
+++ b/gcc-103-substitution-bug-fix.patch
@@ -0,0 +1,78 @@
+--- a/gcc/cp/pt.c
++++ b/gcc/cp/pt.c
+@@ -13750,45 +13750,6 @@ tsubst_function_decl (tree t, tree args, tsubst_flags_t complain,
+ 	  if (tree spec = retrieve_specialization (gen_tmpl, argvec, hash))
+ 	    return spec;
+ 	}
+-
+-      /* We can see more levels of arguments than parameters if
+-	 there was a specialization of a member template, like
+-	 this:
+-
+-	 template <class T> struct S { template <class U> void f(); }
+-	 template <> template <class U> void S<int>::f(U);
+-
+-	 Here, we'll be substituting into the specialization,
+-	 because that's where we can find the code we actually
+-	 want to generate, but we'll have enough arguments for
+-	 the most general template.
+-
+-	 We also deal with the peculiar case:
+-
+-	 template <class T> struct S {
+-	   template <class U> friend void f();
+-	 };
+-	 template <class U> void f() {}
+-	 template S<int>;
+-	 template void f<double>();
+-
+-	 Here, the ARGS for the instantiation of will be {int,
+-	 double}.  But, we only need as many ARGS as there are
+-	 levels of template parameters in CODE_PATTERN.  We are
+-	 careful not to get fooled into reducing the ARGS in
+-	 situations like:
+-
+-	 template <class T> struct S { template <class U> void f(U); }
+-	 template <class T> template <> void S<T>::f(int) {}
+-
+-	 which we can spot because the pattern will be a
+-	 specialization in this case.  */
+-      int args_depth = TMPL_ARGS_DEPTH (args);
+-      int parms_depth =
+-	TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (DECL_TI_TEMPLATE (t)));
+-
+-      if (args_depth > parms_depth && !DECL_TEMPLATE_SPECIALIZATION (t))
+-	args = get_innermost_template_args (args, parms_depth);
+     }
+   else
+     {
+diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-72.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-72.C
+new file mode 100644
+index 00000000000..8009756dcba
+--- /dev/null
++++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-72.C
+@@ -0,0 +1,9 @@
++// PR c++/100102
++// { dg-do compile { target c++11 } }
++
++template<int()> struct ratio;
++template<class T, class U> struct duration {
++  static constexpr int _S_gcd();
++  template<class> using __is_harmonic = ratio<_S_gcd>;
++  using type = __is_harmonic<int>;
++};
+diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-72a.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-72a.C
+new file mode 100644
+index 00000000000..a4443e18f9d
+--- /dev/null
++++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-72a.C
+@@ -0,0 +1,9 @@
++// PR c++/100102
++// { dg-do compile { target c++11 } }
++
++template<int> struct ratio;
++template<class T> struct duration {
++  static constexpr int _S_gcd();
++  template<class> using __is_harmonic = ratio<(duration::_S_gcd)()>;
++  using type = __is_harmonic<int>;
++};
diff --git a/gcc.spec b/gcc.spec
index 12fbadeb883..46a64e5eb84 100644
--- a/gcc.spec
+++ b/gcc.spec
@@ -1,10 +1,10 @@
-### RPM external gcc 10.2.0
+### RPM external gcc 10.3.0
 ## USE_COMPILER_VERSION
 ## INITENV +PATH LD_LIBRARY_PATH %{i}/lib64
 # Use the git repository for fetching the sources. This gives us more control while developing
 # a new platform so that we can compile yet to be released versions of the compiler.
 # See: https://gcc.gnu.org/viewcvs/gcc/branches/gcc-8-branch/?view=log
-%define gccTag fd7f82855134bc40c46f06c66413f1ec78404eca
+%define gccTag f00b5710a30f22efc3171c393e56aeb335c3cd39
 %define gccBranch releases/gcc-10
 
 %define moduleName %{n}-%{realversion}
@@ -42,10 +42,12 @@ Source11: https://github.com/westes/flex/releases/download/v%{flexVersion}/flex-
 
 Patch0: gcc-flex-nonfull-path-m4
 Patch1: gcc-flex-disable-doc
+Patch2: gcc-103-substitution-bug-fix
 
 %prep
 
 %setup -T -b 0 -n %{moduleName}
+%patch2 -p1
 
 # Filter out private stuff from RPM requires headers.
 cat << \EOF > %{name}-req