configure.ac: set -Wreturn-type to error.

diff --git a/re2c/configure.ac b/re2c/configure.ac
index e1ea7cf9921882931180cb516e42e1b22fdf3722..863744c9666d16d9d4d8cf20d3b2e2e9ca3d2d46 100644 (file)
--- a/re2c/configure.ac
+++ b/re2c/configure.ac
@@ -67,6 +67,7 @@ TRY_CXXFLAG([-Wredundant-decls])
 TRY_CXXFLAG([-Wsuggest-attribute=format])
 TRY_CXXFLAG([-Wconversion])
 TRY_CXXFLAG([-Wsign-conversion])
+TRY_CXXFLAG([-Werror=return-type])
 TRY_CXXFLAG([-O2])
 TRY_CXXFLAG([-Weverything], m4_join([ ],
     [-Wno-unknown-warning-option],  dnl CLANG eats some GCC options only to warn they are unknown