Code in main/solenv/inc/tg_compv.mk and main/solenv/bin/getcompver.awk assumes that "gcc -dumpversion" will return a canonical version number in the form x.y.z.

Unfortunately, recent GCC versions no longer guarantee this convention:

https://gcc.gnu.org/onlinedocs/gcc/Developer-Options.html#index-dumpversion

"Print the compiler version (for example, 3.0, 6.3.0 or 7)—and don’t do anything else. This is the compiler version used in filesystem paths, specs, can be depending on how the compiler has been configured just a single number (major version), two numbers separated by dot (major and minor version) or three numbers separated by dots (major, minor and patchlevel version)."

The right one to use would be -dumpfullversion (same URL):

"Print the full compiler version, always 3 numbers separated by dots, major, minor and patchlevel version."

Unfortunately, it seems (but I haven't checked yet) that old gcc versions do not support -dumpfullversion.

Note: "6.3" does not mean "6.3.0"; you can get "6.3" for "6.3.0" or "6.3.1", and you can get "7" for "7.0.0", "7.3.0", "7.3.1"... the version is simply truncated, and configuration depends on the distribution.

When the output is in the form "x.y", we already expand it to "x.y.0", which is wrong (see above).

The following patch to main/solenv/bin/getcompver.awk extends it to expand "7" to "7.0.0" and is equally wrong, but it allows the build to continue.

---
@@ -46,6 +46,13 @@
     x = match( $0, /[0-9]*\.[0-9]*\.[0-9]*/ )
     CCversion = substr( $0, RSTART, RLENGTH)
 }
+/^[0-9]*\x0d*$/ {
+    if ( compiler_matched == 0 ) {
+    # Comparison assumes the compiler version is reported as x.y.z.
+    # For GCC one should use -dumpfullversion but it won't work on old versions.
+    	CCversion = $0 ".0.0"
+    }
+}
 /^[0-9]*[.][0-9]*\x0d*$/ {
     if ( compiler_matched == 0 ) {
 # need to blow to x.xx.xx for comparing
---

The proper solution is: test if -dumpfullversion is supported and use its output in case, otherwise revert to -dumpversion and go through all current hacks.

Note that the awk file is not specific to gcc, so changes must go in main/solenv/inc/tg_compv.mk