[travis-ci] Add check for \opt without argument

Author: tkoeppe

.travis.yml

@@ -8,6 +8,7 @@ env:
   - BUILD_TYPE=complete  # build manually and regenerate figures, grammar, and cross-references
   - BUILD_TYPE=check-whitespace  # check for whitespace at the ends of lines
   - BUILD_TYPE=check-newlines  # check for blank lines at the ends of files
+  - BUILD_TYPE=check-macro-use   # check for proper macro use
 
 script:
   # Build std.pdf
@@ -43,6 +44,11 @@ script:
   - if [ "$BUILD_TYPE" = "check-newlines" ]; then
       for f in source/*.tex; do [ $(tail -c 2 $f | wc -l) -eq 1 ] || exit 1; done;
     fi
+  # Fail if macros are used incorrectly
+  - if [ "$BUILD_TYPE" = "check-macro-use" ]; then
+      ! grep '\\opt[^{}]' source/*.tex;
+      ! grep 'opt{}' source/*.tex;
+    fi
   # Check to see if generated files are out-dated
   - pushd source
   - for FIGURE in *.dot; do