Substantially restructure function-like macro argument parsing.
Highlights: PP::isNextPPTokenLParen() no longer eats the ( 
when present.  We now simplify slightly the logic parsing
macro arguments.  We now handle PR3937 and other related cases
correctly.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69411 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Preprocessor/macro_fn.c b/test/Preprocessor/macro_fn.c
new file mode 100644
index 0000000..8dc8b77
--- /dev/null
+++ b/test/Preprocessor/macro_fn.c
@@ -0,0 +1,27 @@
+/* RUN: clang-cc %s -Eonly -std=c89 -pedantic -verify
+*/
+/* PR3937 */
+#define zero() 0
+#define one(x) 0
+#define two(x, y) 0
+
+zero()
+zero(1);          /* expected-error {{too many arguments provided to function-like macro invocation}} */
+zero(1, 2, 3);    /* expected-error {{too many arguments provided to function-like macro invocation}} */
+
+one()   /* ok */
+one(a)
+one(a,)           /* expected-error {{too many arguments provided to function-like macro invocation}} */
+one(a, b)         /* expected-error {{too many arguments provided to function-like macro invocation}} */
+
+two()       /* expected-error {{too few arguments provided to function-like macro invocation}} */
+two(a)      /* expected-error {{too few arguments provided to function-like macro invocation}} */
+two(a,b)
+two(a, )    /* expected-warning {{empty macro arguments were standardized in C99}} */
+two(a,b,c)  /* expected-error {{too many arguments provided to function-like macro invocation}} */
+two(
+    ,     /* expected-warning {{empty macro arguments were standardized in C99}} */
+    ,     /* expected-warning {{empty macro arguments were standardized in C99}}  \
+             expected-error {{too many arguments provided to function-like macro invocation}} */
+    )     
+two(,)      /* expected-warning 2 {{empty macro arguments were standardized in C99}} */