Merge remote-tracking branch 'origin/maint'

* origin/maint: (24 commits)
  tests: calc: modernize the use of locations
  tests: remove useless location initializations
  lalr1.cc: always initialize yylval.
  tests: check that C and C++ objects can be linked together.
  yacc.c: also disable -Wuninitialized.
  glr.cc, yacc.c: initialize yylloc properly
  yacc.c, glr.c: a better YY_LOCATION_PRINT
  yacc.c: simplify initialization
  doc: formatting changes
  c++: fix position operator signatures
  tests: remove useless location initialization.
  tests: fix locations in C
  tests: handle %parse-param in the generated yyerror
  tests: simplifications
  grammars: fix display of nul character in error message
  tests: sort
  tests: cosmetic changes
  comment changes
  autoconf: update
  gnulib: update
  ...

Conflicts:
	data/lalr1.cc
	gnulib
	src/scan-gram.l
	submodules/autoconf
	tests/calc.at

tests/headers.at

@@ -241,9 +241,6 @@ AT_TEST([x7], [%define api.push-pull both])
 AT_TEST([x8], [%define api.pure %define api.push-pull both])
 #AT_TEST([x5], [%locations %language "c++" %glr-parser])
 
-AT_COMPILE_CXX([parser], [[x[1-8].o -DCC_IS_CXX=$CC_IS_CXX main.cc]])
-AT_CHECK([./parser], [0], [[expout]])
-
 # Check that the headers are self-contained, and protected against
 # multiple inclusions.  While at it, check they are sane for C++.
 for h in *.h *.hh
@@ -257,6 +254,12 @@ EOF
   AT_COMPILE_CXX([$h.o])
 done
 
+# Do this late, so that other checks have been performed.
+AT_SKIP_IF_CANNOT_LINK_C_AND_CXX
+
+AT_COMPILE_CXX([parser], [[x[1-8].o -DCC_IS_CXX=$CC_IS_CXX main.cc]])
+AT_CHECK([./parser], [0], [[expout]])
+
 m4_popdef([AT_TEST])
 
 AT_CLEANUP