build: be less aggressive about -fanalyzer

* configure.ac: Don’t enable -fanalyzer unless configured with the
new --enable-gcc-warnings=expensive option.  See thread at:
https://lists.gnu.org/r/coreutils/2020-07/msg00011.html

diff --git a/configure.ac b/configure.ac
index 0afbff6271147a5c94679fe4fe16e6992c1c21a1..69d4e7d7ffd132fa2b5c57e75a66121bde6e310f 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -89,10 +89,14 @@ AC_DEFUN([gl_GCC_VERSION_IFELSE],
 )
 
 AC_ARG_ENABLE([gcc-warnings],
-  [AS_HELP_STRING([--enable-gcc-warnings],
-     [turn on many GCC warnings (for developers; best with GNU make)])],
+  [AS_HELP_STRING([--enable-gcc-warnings@<:@=TYPE@:>@],
+    [control generation of GCC warnings.  The TYPE 'no' disables
+     warnings (default for non-developer builds); 'yes' generates
+     cheap warnings if available (default for developer builds);
+     'expensive' in addition generates expensive-to-compute warnings
+     if available.])],
   [case $enableval in
-     yes|no) ;;
+     no|yes|expensive) ;;
      *)      AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
    esac
    gl_gcc_warnings=$enableval],
@@ -108,12 +112,18 @@ AC_ARG_ENABLE([gcc-warnings],
                           && gl_gcc_warnings=yes])]
 )
 
-if test "$gl_gcc_warnings" = yes; then
+if test $gl_gcc_warnings != no; then
   gl_WARN_ADD([-Werror], [WERROR_CFLAGS])
   AC_SUBST([WERROR_CFLAGS])
 
-  nw=
+  ew=
+  AS_IF([test $gl_gcc_warnings != expensive],
+    [# -fanalyzer and related options slow GCC considerably.
+     ew="$ew -fanalyzer -Wno-analyzer-double-free -Wno-analyzer-malloc-leak"
+     ew="$ew -Wno-analyzer-null-dereference -Wno-analyzer-use-after-free"])
+
   # This, $nw, is the list of warnings we disable.
+  nw=$ew
   nw="$nw -Wdeclaration-after-statement" # too useful to forbid
   nw="$nw -Waggregate-return"       # anachronistic
   nw="$nw -Wlong-long"              # C90 is anachronistic (lib/gethrxtime.h)
@@ -190,7 +200,7 @@ if test "$gl_gcc_warnings" = yes; then
 
   # We use a slightly smaller set of warning options for lib/.
   # Remove the following and save the result in GNULIB_WARN_CFLAGS.
-  nw=
+  nw=$ew
   nw="$nw -Wduplicated-branches"    # Too many false alarms
   nw="$nw -Wformat-truncation=2"
   nw="$nw -Wstrict-overflow"