Add g++/11 and clang to Travis

.travis.yml

@@ -11,10 +11,9 @@ branches:
 
 dist: trusty
 
-language: c
+language: c++
 
-compiler:
-  - gcc
+compiler: gcc
 
 addons:
   apt:
@@ -43,30 +42,28 @@ matrix:
 
   include:
     # Simple integrated status tests check.
-    - env:
-      - SCRIPT=ci_boost_status
+    - env: SCRIPT=ci_boost_status
 
     # Run 'quick' tests.
-    - env:
-      - SCRIPT=ci_boost_status
-      - TARGET=quick
+    - env: SCRIPT=ci_boost_status TARGET=quick TOOLSET=gcc
+
+    - env: SCRIPT=ci_boost_status TARGET=quick TOOLSET=gcc CXXSTD=11
+
+    - env: SCRIPT=ci_boost_status TARGET=quick TOOLSET=clang
+      compiler: clang
 
     # Build release package, but skip the final archive/upload step,
     #  to stay under time limit
     #
     # Skip EOL=LF and EOL=CRLF because they often time out
 
-    - env:
-      - SCRIPT=ci_boost_release
-      - EOL=NONE
+    - env: SCRIPT=ci_boost_release EOL=NONE
 
     # Library requirements tests.
-    - env:
-      - SCRIPT=ci_boost_library_check
+    - env: SCRIPT=ci_boost_library_check
 
   allow_failures:
-    - env:
-      - SCRIPT=ci_boost_library_check
+    - env: SCRIPT=ci_boost_library_check
 
 before_install:
   # Fetch the scripts to do the actual building/testing.