[m-rev.] for review: avoid test failures in hlc grades with GCC 12

[Julien Fischer]

For review by anyone.

Five of the six tests mentioned below trigger the Mercury compiler's own
infinite recursion warning. The one test that does not do that but does
get a warning from GCC is tests/valid/higher_order5.m.  In that case GCC,
has the advantage of seeing the code after the call to the function id/1
has been inlined into the body of definite_vars/3.

-----------------------------

Avoid test failures in hlc grades with GCC 12.

GCC 12 has a new warning, -Winfinite-recursion, which is triggered by six of
the tests in tests/valid.  Because we also use -Werror, those tests now fail.

configure.ac:
scripts/mgnuc.in:
      When using GCC 12 or higher, compile with -Wno-infinite-recursion
      in order to avoid the above failures.

Julien.

diff --git a/configure.ac b/configure.ac
index 871cbe5..33d4377 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4395,6 +4395,14 @@ case "$mercury_cv_cc_type" in
              ;;
          esac

+        # See scripts/mgnuc.in for an explanation of why we set
+        # -Wno-infinite-recursion here.
+        case "$C_COMPILER_TYPE" in
+            gcc_1[[2-9]]_*)
+                CFLAGS_FOR_WARNINGS="$CFLAGS_FOR_WARNINGS -Wno-infinite-recursion"
+            ;;
+        esac
+
          # Enabling -fomit-frame-pointer causes setjmp/longjmp to misbehave
          # with MinGW on Windows XP.
          case "$host" in
diff --git a/scripts/mgnuc.in b/scripts/mgnuc.in
index 649539e..9e007bd 100755
--- a/scripts/mgnuc.in
+++ b/scripts/mgnuc.in
@@ -583,6 +583,15 @@ case "${C_COMPILER_TYPE}" in
      ;;
  esac

+# Disable the warnings about infinite recursion generated by GCC 12
+# onwards. These cause several of the tests in tests/valid to fail
+# in hlc grades due to -Werror also being enabled.
+case "${C_COMPILER_TYPE}" in
+    gcc_1[2-9]_*)
+        CHECK_OPTS="${CHECK_OPTS} -Wno-infinite-recursion"
+    ;;
+esac
+
  case ${COMPILER} in gcc)
      case "${FULLARCH}" in
          i*86*)