Hi:

I use buildroot External toolchain
$ make menuconfig
Toolchain  --->
    External toolchain gcc version (9.x)  ---> 

gcc is ubuntu20.04 by `sudo apt install gcc` install, it's version is 9.3.0, so gcc -dumpversion is 9

but toolchain/helpers.mk check_gcc_version function to display error
I fixed this bug, as follows:

diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
index 44d0c83d1e..7c7819f9a6 100644
--- a/toolchain/helpers.mk
+++ b/toolchain/helpers.mk
@@ -184,7 +184,7 @@ check_gcc_version = \
                exit 0 ; \
        fi; \
        real_version=`$(1) -dumpversion` ; \
-       if [[ ! "$${real_version}" =~ ^$${expected_version}\. ]] ; then \
+       if [[ ! "$${real_version}" =~ ^$${expected_version} ]] ; then \
                printf "Incorrect selection of gcc version: expected %s.x, got %s\n" \
                        "$${expected_version}" "$${real_version}" ; \
                exit 1 ; \