[C PATCH] Better location for switch warnings (PR c/30020)

[Marek Polacek <polacek at redhat dot com>]

It is trivial to pass the location from c_add_case_label down to
check_case_bounds, so do that.  With it, we instead of

i.c:4:3: warning: case label value is less than minimum value for type
   switch (c) { case 42: case -1: return -1; };
   ^
output
i.c:4:25: warning: case label value is less than minimum value for type
   switch (c) { case 42: case -1: return -1; };
                         ^
which is better.

Tested x86_64, ok for trunk?

2014-06-04  Marek Polacek  <polacek@redhat.com>

	PR c/30020
	* c-common.c (check_case_bounds): Add location parameter.
	Use it.
	(c_add_case_label): Pass loc to check_case_bounds.

	* c-c++-common/pr30020.c: New test.

diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index 6ec14fc..07a1798 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -301,7 +301,7 @@ struct visibility_flags visibility_options;
 
 static tree c_fully_fold_internal (tree expr, bool, bool *, bool *);
 static tree check_case_value (tree);
-static bool check_case_bounds (tree, tree, tree *, tree *);
+static bool check_case_bounds (location_t, tree, tree, tree *, tree *);
 
 static tree handle_packed_attribute (tree *, tree, tree, int, bool *);
 static tree handle_nocommon_attribute (tree *, tree, tree, int, bool *);
@@ -3355,7 +3355,7 @@ check_case_value (tree value)
    untouched) or false if the label is out of range.  */
 
 static bool
-check_case_bounds (tree type, tree orig_type,
+check_case_bounds (location_t loc, tree type, tree orig_type,
 		   tree *case_low_p, tree *case_high_p)
 {
   tree min_value, max_value;
@@ -3373,7 +3373,8 @@ check_case_bounds (tree type, tree orig_type,
   if (tree_int_cst_compare (case_low, min_value) < 0
       && tree_int_cst_compare (case_high, min_value) < 0)
     {
-      warning (0, "case label value is less than minimum value for type");
+      warning_at (loc, 0, "case label value is less than minimum value "
+		  "for type");
       return false;
     }
 
@@ -3381,7 +3382,7 @@ check_case_bounds (tree type, tree orig_type,
   if (tree_int_cst_compare (case_low, max_value) > 0
       && tree_int_cst_compare (case_high, max_value) > 0)
     {
-      warning (0, "case label value exceeds maximum value for type");
+      warning_at (loc, 0, "case label value exceeds maximum value for type");
       return false;
     }
 
@@ -3389,8 +3390,8 @@ check_case_bounds (tree type, tree orig_type,
   if (tree_int_cst_compare (case_high, min_value) >= 0
       && tree_int_cst_compare (case_low, min_value) < 0)
     {
-      warning (0, "lower value in case label range"
-	       " less than minimum value for type");
+      warning_at (loc, 0, "lower value in case label range"
+		  " less than minimum value for type");
       case_low = min_value;
     }
 
@@ -3398,8 +3399,8 @@ check_case_bounds (tree type, tree orig_type,
   if (tree_int_cst_compare (case_low, max_value) <= 0
       && tree_int_cst_compare (case_high, max_value) > 0)
     {
-      warning (0, "upper value in case label range"
-	       " exceeds maximum value for type");
+      warning_at (loc, 0, "upper value in case label range"
+		  " exceeds maximum value for type");
       case_high = max_value;
     }
 
@@ -6014,7 +6015,7 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond, tree orig_type,
      expression.  If both low_value and high_value are out of range,
      don't insert the case label and return NULL_TREE.  */
   if (low_value
-      && !check_case_bounds (type, orig_type,
+      && !check_case_bounds (loc, type, orig_type,
 			     &low_value, high_value ? &high_value : NULL))
     return NULL_TREE;
 
diff --git gcc/testsuite/c-c++-common/pr30020.c gcc/testsuite/c-c++-common/pr30020.c
index e69de29..b8082cd 100644
--- gcc/testsuite/c-c++-common/pr30020.c
+++ gcc/testsuite/c-c++-common/pr30020.c
@@ -0,0 +1,12 @@
+/* PR c/30020 */
+/* { dg-do compile } */
+
+int
+foo (unsigned char c)
+{
+  switch (c) { case 42: case -1: return -1; }; /* { dg-warning "25:case label value" } */
+  switch (c) { case 42: case 300: return -1; }; /* { dg-warning "25:case label value" } */
+  switch (c) { case 42: case -1 ... 2: return -1; }; /* { dg-warning "25:lower value in case" } */
+  switch (c) { case 42: case 250 ... 300: return -1; }; /* { dg-warning "25:upper value in case" } */
+  return 0;
+}

	Marek