re PR c/64249 (Missing warning for if (A) else if (A))

	PR c/64249
	* c-common.c (warn_duplicated_cond_add_or_warn): New function.
	* c-common.h (warn_duplicated_cond_add_or_warn): Declare.
	* c.opt (Wduplicated-cond): New option.

	* c-parser.c (c_parser_statement_after_labels): Add CHAIN parameter
	and pass it down to c_parser_if_statement.
	(c_parser_else_body): Add CHAIN parameter and pass it down to
	c_parser_statement_after_labels.
	(c_parser_if_statement): Add CHAIN parameter.  Add code to warn about
	duplicated if-else-if conditions.

	* parser.c (cp_parser_statement): Add CHAIN parameter and pass it
	down to cp_parser_selection_statement.
	(cp_parser_selection_statement): Add CHAIN parameter.  Add code to
	warn about duplicated if-else-if conditions.
	(cp_parser_implicitly_scoped_statement): Add CHAIN parameter and pass
	it down to cp_parser_statement.

	* doc/invoke.texi: Document -Wduplicated-cond.
	* Makefile.in (insn-latencytab.o): Use -Wno-duplicated-cond.
	(insn-dfatab.o): Likewise.
	* genemit.c (gen_exp): Rewrite condition to avoid -Wduplicated-cond
	warning.

	* c-c++-common/Wduplicated-cond-1.c: New test.
	* c-c++-common/Wduplicated-cond-2.c: New test.
	* c-c++-common/Wduplicated-cond-3.c: New test.
	* c-c++-common/Wduplicated-cond-4.c: New test.
	* c-c++-common/Wmisleading-indentation.c (fn_37): Avoid
	-Wduplicated-cond warning.

From-SVN: r228388

2 files changed, 58 insertions, 12 deletions

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 577fdc0..7c0051f 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,13 @@
+2015-10-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c/64249
+	* c-parser.c (c_parser_statement_after_labels): Add CHAIN parameter
+	and pass it down to c_parser_if_statement.
+	(c_parser_else_body): Add CHAIN parameter and pass it down to
+	c_parser_statement_after_labels.
+	(c_parser_if_statement): Add CHAIN parameter.  Add code to warn about
+	duplicated if-else-if conditions.
+
 2015-10-01  Marek Polacek  <polacek@redhat.com>
 
 	* c-typeck.c (convert_for_assignment): Improve commentary.
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index 2fab3f0..00fa238 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -1198,8 +1198,8 @@ static tree c_parser_compound_statement (c_parser *);
 static void c_parser_compound_statement_nostart (c_parser *);
 static void c_parser_label (c_parser *);
 static void c_parser_statement (c_parser *);
-static void c_parser_statement_after_labels (c_parser *);
-static void c_parser_if_statement (c_parser *);
+static void c_parser_statement_after_labels (c_parser *, vec<tree> * = NULL);
+static void c_parser_if_statement (c_parser *, vec<tree> *);
 static void c_parser_switch_statement (c_parser *);
 static void c_parser_while_statement (c_parser *, bool);
 static void c_parser_do_statement (c_parser *, bool);
@@ -4961,10 +4961,11 @@ c_parser_statement (c_parser *parser)
   c_parser_statement_after_labels (parser);
 }
 
-/* Parse a statement, other than a labeled statement.  */
+/* Parse a statement, other than a labeled statement.  CHAIN is a vector
+   of if-else-if conditions.  */
 
 static void
-c_parser_statement_after_labels (c_parser *parser)
+c_parser_statement_after_labels (c_parser *parser, vec<tree> *chain)
 {
   location_t loc = c_parser_peek_token (parser)->location;
   tree stmt = NULL_TREE;
@@ -4979,7 +4980,7 @@ c_parser_statement_after_labels (c_parser *parser)
       switch (c_parser_peek_token (parser)->keyword)
 	{
 	case RID_IF:
-	  c_parser_if_statement (parser);
+	  c_parser_if_statement (parser, chain);
 	  break;
 	case RID_SWITCH:
 	  c_parser_switch_statement (parser);
@@ -5230,10 +5231,12 @@ c_parser_if_body (c_parser *parser, bool *if_p,
 
 /* Parse the else body of an if statement.  This is just parsing a
    statement but (a) it is a block in C99, (b) we handle an empty body
-   specially for the sake of -Wempty-body warnings.  */
+   specially for the sake of -Wempty-body warnings.  CHAIN is a vector
+   of if-else-if conditions.  */
 
 static tree
-c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo)
+c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo,
+		    vec<tree> *chain)
 {
   location_t body_loc = c_parser_peek_token (parser)->location;
   tree block = c_begin_compound_stmt (flag_isoc99);
@@ -5251,7 +5254,7 @@ c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo)
       c_parser_consume_token (parser);
     }
   else
-    c_parser_statement_after_labels (parser);
+    c_parser_statement_after_labels (parser, chain);
 
   token_indent_info next_tinfo
     = get_token_indent_info (c_parser_peek_token (parser));
@@ -5265,10 +5268,11 @@ c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo)
    if-statement:
      if ( expression ) statement
      if ( expression ) statement else statement
-*/
+
+  CHAIN is a vector of if-else-if conditions.  */
 
 static void
-c_parser_if_statement (c_parser *parser)
+c_parser_if_statement (c_parser *parser, vec<tree> *chain)
 {
   tree block;
   location_t loc;
@@ -5294,15 +5298,47 @@ c_parser_if_statement (c_parser *parser)
   parser->in_if_block = true;
   first_body = c_parser_if_body (parser, &first_if, if_tinfo);
   parser->in_if_block = in_if_block;
+
+  if (warn_duplicated_cond)
+    warn_duplicated_cond_add_or_warn (EXPR_LOCATION (cond), cond, &chain);
+
   if (c_parser_next_token_is_keyword (parser, RID_ELSE))
     {
       token_indent_info else_tinfo
 	= get_token_indent_info (c_parser_peek_token (parser));
       c_parser_consume_token (parser);
-      second_body = c_parser_else_body (parser, else_tinfo);
+      if (warn_duplicated_cond)
+	{
+	  if (c_parser_next_token_is_keyword (parser, RID_IF)
+	      && chain == NULL)
+	    {
+	      /* We've got "if (COND) else if (COND2)".  Start the
+		 condition chain and add COND as the first element.  */
+	      chain = new vec<tree> ();
+	      if (!CONSTANT_CLASS_P (cond) && !TREE_SIDE_EFFECTS (cond))
+		chain->safe_push (cond);
+	    }
+	  else if (!c_parser_next_token_is_keyword (parser, RID_IF))
+	    {
+	      /* This is if-else without subsequent if.  Zap the condition
+		 chain; we would have already warned at this point.  */
+	      delete chain;
+	      chain = NULL;
+	    }
+	}
+      second_body = c_parser_else_body (parser, else_tinfo, chain);
     }
   else
-    second_body = NULL_TREE;
+    {
+      second_body = NULL_TREE;
+      if (warn_duplicated_cond)
+	{
+	  /* This if statement does not have an else clause.  We don't
+	     need the condition chain anymore.  */
+	  delete chain;
+	  chain = NULL;
+	}
+    }
   c_finish_if_stmt (loc, cond, first_body, second_body, first_if);
   if_stmt = c_end_compound_stmt (loc, block, flag_isoc99);