preproc: fix %undef of macro aliases, and add %ifdefalias

Macro aliases can legitimately point to nonexistent
macros. Furthermore, %undef should remove the pointed-at macro, not
the alias. This led to an infinite loop in the existing code; fix
that.

Add an %ifdefalias directive to test for the existence of an alias.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/test/defalias.asm b/test/defalias.asm
new file mode 100644
index 00000000..1641a1f1
--- /dev/null
+++ b/test/defalias.asm
@@ -0,0 +1,52 @@
+%defalias foo bar
+%ifdef foo
+  %error "foo should not be defined here!"
+%endif
+
+%define foo 33
+%ifndef foo
+  %error "foo should be defined here!"
+%endif
+%ifndef bar
+  %error "bar should be defined here!"
+%endif
+%if bar != 33
+  %error "bar should have the value 33 here"
+%endif
+
+%define bar 34
+%if foo != 34
+  %error "foo should have the value 34 here"
+%endif
+
+%undef foo
+%ifdef foo
+  %error "foo should not be defined here!"
+%endif
+%ifdef bar
+  %error "bar should not be defined here!"
+%endif
+
+%ifndefalias foo
+  %error "foo was removed as an alias!"
+%endif
+
+%define bar 35
+%if foo != 35
+  %error "foo should have the value 35 here"
+%endif
+
+%define foo 36
+%if bar != 36
+  %error "bar should have the value 36 here"
+%endif
+
+%undefalias foo
+%ifdef foo
+  %error "foo is still defined after %undefalias"
+%elifdefalias foo
+  %error "foo is undefined, but still an alias"
+%endif
+%ifndef bar
+  %error "bar disappeared after %undefalias foo"
+%endif