re PR preprocessor/60570 (expression in 'elif' directive mis-diagnosed as error when group will be skipped)

	DR#412
	PR preprocessor/60570
	* directives.c (do_elif): Don't evaluate #elif conditionals
	when they don't need to be.

	* gcc.dg/cpp/pr36320.c: Turn dg-error into dg-bogus.
	* gcc.dg/cpp/pr60570.c: New test.

From-SVN: r220035

5 files changed, 72 insertions, 18 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 86753d6..cf9b478 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2015-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR preprocessor/60570
+	* gcc.dg/cpp/pr36320.c: Turn dg-error into dg-bogus.
+	* gcc.dg/cpp/pr60570.c: New test.
+
 2015-01-23  Richard Biener  <rguenther@suse.de>
 
 	PR testsuite/63439
diff --git a/gcc/testsuite/gcc.dg/cpp/pr36320.c b/gcc/testsuite/gcc.dg/cpp/pr36320.c
index d136a69..cc2baa7 100644
--- a/gcc/testsuite/gcc.dg/cpp/pr36320.c
+++ b/gcc/testsuite/gcc.dg/cpp/pr36320.c
@@ -1,8 +1,8 @@
 /* PR 36320 - #elif still requires valid expression.  */
-
+/* DR#412: #elif doesn't have to be valid expression (PR60570).  */
 /* { dg-do preprocess } */
 
 int z;
 #if 1
-#elif   /* { dg-error "with no expression" } */
+#elif	/* { dg-bogus "with no expression" } */
 #endif
diff --git a/gcc/testsuite/gcc.dg/cpp/pr60570.c b/gcc/testsuite/gcc.dg/cpp/pr60570.c
new file mode 100644
index 0000000..4755206
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr60570.c
@@ -0,0 +1,48 @@
+/* PR preprocessor/60570 */
+/* { dg-do preprocess } */
+
+#if 1
+int i;
+#elif 1/0
+#endif
+
+#if 1
+int j;
+#elif
+#endif
+
+#if 0
+#elif 1/0	/* { dg-error "division by zero" } */
+int k;
+#endif
+
+#if 0
+#elif		/* { dg-error "with no expression" } */
+int n;
+#endif
+
+#if 1
+# if 1
+int l;
+# elif 1/0
+# endif
+#endif
+
+#if 1
+# if 1
+int l;
+# elif
+# endif
+#endif
+
+#if 1
+# if 0
+# elif 1/0	/* { dg-error "division by zero" } */
+# endif
+#endif
+
+#if 1
+# if 0
+# elif		/* { dg-error "with no expression" } */
+# endif
+#endif
diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 2325161..41aa56f 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,10 @@
+2015-01-23  Marek Polacek  <polacek@redhat.com>
+
+	DR#412
+	PR preprocessor/60570
+	* directives.c (do_elif): Don't evaluate #elif conditionals
+	when they don't need to be.
+
 2015-01-16  Jakub Jelinek  <jakub@redhat.com>
 
 	* expr.c (cpp_classify_number): Add N_() around ?: string
diff --git a/libcpp/directives.c b/libcpp/directives.c
index ab4f15c..37cd109 100644
--- a/libcpp/directives.c
+++ b/libcpp/directives.c
@@ -2036,23 +2036,16 @@ do_elif (cpp_reader *pfile)
 	}
       ifs->type = T_ELIF;
 
-      if (! ifs->was_skipping)
+      /* See DR#412: "Only the first group whose control condition
+	 evaluates to true (nonzero) is processed; any following groups
+	 are skipped and their controlling directives are processed as
+	 if they were in a group that is skipped."  */
+      if (ifs->skip_elses)
+	pfile->state.skipping = 1;
+      else
 	{
-	  bool value;
-	  /* The standard mandates that the expression be parsed even
-	     if we are skipping elses at this point -- the lexical
-	     restrictions on #elif only apply to skipped groups, but
-	     this group is not being skipped.  Temporarily set
-	     skipping to false to get lexer warnings.  */
-	  pfile->state.skipping = 0;
-	  value = _cpp_parse_expr (pfile, false);
-	  if (ifs->skip_elses)
-	    pfile->state.skipping = 1;
-	  else
-	    {
-	      pfile->state.skipping = ! value;
-	      ifs->skip_elses = value;
-	    }
+	  pfile->state.skipping = ! _cpp_parse_expr (pfile, false);
+	  ifs->skip_elses = ! pfile->state.skipping;
 	}
 
       /* Invalidate any controlling macro.  */