Re: [C PATCH] Follow-up fix to the misclassified token problem (PR c/67784)

[Marek Polacek <polacek at redhat dot com>]

On Tue, Apr 26, 2016 at 11:44:52AM +0000, Joseph Myers wrote:
> On Tue, 26 Apr 2016, Marek Polacek wrote:
> 
> > This PR was reopened, because the exact same problem with treating a TYPENAME
> > wrongly as an ID was found when using just if-clause, without an enclosing for
> > loop.  More details: <https://gcc.gnu.org/ml/gcc-patches/2015-11/msg01588.html>.
> > That fix had a follow-up, because it broke some ObjC code.
> > 
> > To fix this, we need to use the (amended) token reclassification even when
> > parsing an if statement.  I factored the code into a separate function so as to
> > not repeat the very same code.
> > 
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> I think you need more thorough testcases, to cover the cases where the if 
> statement with no else forms the body of a switch or while statement, and 
> the declaration in question appears in the expression of that switch or 
> while statement, e.g.
> 
> typedef int T;
> 
> switch (sizeof (enum { T }))
>   if (1)
>     ;
> T x;

Ah, right, that revealed two more places that were missing the
c_parser_maybe_reclassify_token call.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2016-04-26  Marek Polacek  <polacek@redhat.com>

	PR c/67784
	* c-parser.c (c_parser_maybe_reclassify_token): New function factored
	out of ...
	(c_parser_for_statement): ... here.
	(c_parser_if_statement): Use it.
	(c_parser_switch_statement): Use it.
	(c_parser_while_statement): Use it.

	* gcc.dg/pr67784-3.c: New test.
	* gcc.dg/pr67784-4.c: New test.
	* gcc.dg/pr67784-5.c: New test.

diff --git gcc/c/c-parser.c gcc/c/c-parser.c
index bdd669d..74423a6 100644
--- gcc/c/c-parser.c
+++ gcc/c/c-parser.c
@@ -5425,6 +5425,43 @@ c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo,
   return c_end_compound_stmt (body_loc, block, flag_isoc99);
 }
 
+/* We might need to reclassify any previously-lexed identifier, e.g.
+   when we've left a for loop with an if-statement without else in the
+   body - we might have used a wrong scope for the token.  See PR67784.  */
+
+static void
+c_parser_maybe_reclassify_token (c_parser *parser)
+{
+  if (c_parser_next_token_is (parser, CPP_NAME))
+    {
+      c_token *token = c_parser_peek_token (parser);
+
+      if (token->id_kind != C_ID_CLASSNAME)
+	{
+	  tree decl = lookup_name (token->value);
+
+	  token->id_kind = C_ID_ID;
+	  if (decl)
+	    {
+	      if (TREE_CODE (decl) == TYPE_DECL)
+		token->id_kind = C_ID_TYPENAME;
+	    }
+	  else if (c_dialect_objc ())
+	    {
+	      tree objc_interface_decl = objc_is_class_name (token->value);
+	      /* Objective-C class names are in the same namespace as
+		 variables and typedefs, and hence are shadowed by local
+		 declarations.  */
+	      if (objc_interface_decl)
+		{
+		  token->value = objc_interface_decl;
+		  token->id_kind = C_ID_CLASSNAME;
+		}
+	    }
+	}
+    }
+}
+
 /* Parse an if statement (C90 6.6.4, C99 6.8.4).
 
    if-statement:
@@ -5523,6 +5560,7 @@ c_parser_if_statement (c_parser *parser, bool *if_p, vec<tree> *chain)
   if (flag_cilkplus && contains_array_notation_expr (if_stmt))
     if_stmt = fix_conditional_array_notations (if_stmt);
   add_stmt (if_stmt);
+  c_parser_maybe_reclassify_token (parser);
 }
 
 /* Parse a switch statement (C90 6.6.4, C99 6.8.4).
@@ -5578,6 +5616,7 @@ c_parser_switch_statement (c_parser *parser)
     }
   c_break_label = save_break;
   add_stmt (c_end_compound_stmt (switch_loc, block, flag_isoc99));
+  c_parser_maybe_reclassify_token (parser);
 }
 
 /* Parse a while statement (C90 6.6.5, C99 6.8.5).
@@ -5620,6 +5659,7 @@ c_parser_while_statement (c_parser *parser, bool ivdep, bool *if_p)
   body = c_parser_c99_block_statement (parser, if_p);
   c_finish_loop (loc, cond, NULL, body, c_break_label, c_cont_label, true);
   add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
+  c_parser_maybe_reclassify_token (parser);
 
   token_indent_info next_tinfo
     = get_token_indent_info (c_parser_peek_token (parser));
@@ -5916,38 +5956,7 @@ c_parser_for_statement (c_parser *parser, bool ivdep, bool *if_p)
   else
     c_finish_loop (loc, cond, incr, body, c_break_label, c_cont_label, true);
   add_stmt (c_end_compound_stmt (loc, block, flag_isoc99 || c_dialect_objc ()));
-
-  /* We might need to reclassify any previously-lexed identifier, e.g.
-     when we've left a for loop with an if-statement without else in the
-     body - we might have used a wrong scope for the token.  See PR67784.  */
-  if (c_parser_next_token_is (parser, CPP_NAME))
-    {
-      c_token *token = c_parser_peek_token (parser);
-
-      if (token->id_kind != C_ID_CLASSNAME)
-	{
-	  tree decl = lookup_name (token->value);
-
-	  token->id_kind = C_ID_ID;
-	  if (decl)
-	    {
-	      if (TREE_CODE (decl) == TYPE_DECL)
-		token->id_kind = C_ID_TYPENAME;
-	    }
-	  else if (c_dialect_objc ())
-	    {
-	      tree objc_interface_decl = objc_is_class_name (token->value);
-	      /* Objective-C class names are in the same namespace as
-		 variables and typedefs, and hence are shadowed by local
-		 declarations.  */
-	      if (objc_interface_decl)
-		{
-		  token->value = objc_interface_decl;
-		  token->id_kind = C_ID_CLASSNAME;
-		}
-	    }
-	}
-    }
+  c_parser_maybe_reclassify_token (parser);
 
   token_indent_info next_tinfo
     = get_token_indent_info (c_parser_peek_token (parser));
diff --git gcc/testsuite/gcc.dg/pr67784-3.c gcc/testsuite/gcc.dg/pr67784-3.c
index e69de29..45e3c44 100644
--- gcc/testsuite/gcc.dg/pr67784-3.c
+++ gcc/testsuite/gcc.dg/pr67784-3.c
@@ -0,0 +1,50 @@
+/* PR c/67784 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+typedef int T;
+
+void
+fn1 (void)
+{
+  if (sizeof (enum { T }) == 0)
+    ;
+  T x;
+}
+
+void
+fn2 (void)
+{
+  int i = 0;
+  if (sizeof (enum { T }) == 0)
+    i++;
+  T x;
+}
+
+void
+fn3 (void)
+{
+  if (sizeof (enum { T }) == 0)
+    {
+    }
+  T x;
+}
+
+void
+fn4 (void)
+{
+  if (sizeof (enum { T }) == 0)
+L:
+    ;
+  T x;
+}
+
+void
+fn5 (void)
+{
+  if (sizeof (enum { T }) == 0)
+    ;
+  else
+    ;
+  T x;
+}
diff --git gcc/testsuite/gcc.dg/pr67784-4.c gcc/testsuite/gcc.dg/pr67784-4.c
index e69de29..81a43fd 100644
--- gcc/testsuite/gcc.dg/pr67784-4.c
+++ gcc/testsuite/gcc.dg/pr67784-4.c
@@ -0,0 +1,55 @@
+/* PR c/67784 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+typedef int T;
+
+void
+fn1 (void)
+{
+  switch (sizeof (enum { T }))
+    if (1)
+      ;
+  T x;
+}
+
+void
+fn2 (void)
+{
+  int i = 0;
+  switch (sizeof (enum { T }))
+    if (1)
+      i++;
+  T x;
+}
+
+void
+fn3 (void)
+{
+  switch (sizeof (enum { T }))
+    if (1)
+      {
+      }
+  T x;
+}
+
+void
+fn4 (void)
+{
+  switch (sizeof (enum { T }))
+    if (1)
+L:
+      ;
+  T x;
+}
+
+void
+fn5 (void)
+{
+  switch (sizeof (enum { T }))
+    if (1)
+      ;
+    else
+      ;
+  T x;
+}
diff --git gcc/testsuite/gcc.dg/pr67784-5.c gcc/testsuite/gcc.dg/pr67784-5.c
index e69de29..0934ece 100644
--- gcc/testsuite/gcc.dg/pr67784-5.c
+++ gcc/testsuite/gcc.dg/pr67784-5.c
@@ -0,0 +1,55 @@
+/* PR c/67784 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+typedef int T;
+
+void
+fn1 (void)
+{
+  while (sizeof (enum { T }))
+    if (1)
+      ;
+  T x;
+}
+
+void
+fn2 (void)
+{
+  int i = 0;
+  while (sizeof (enum { T }))
+    if (1)
+      i++;
+  T x;
+}
+
+void
+fn3 (void)
+{
+  while (sizeof (enum { T }))
+    if (1)
+      {
+      }
+  T x;
+}
+
+void
+fn4 (void)
+{
+  while (sizeof (enum { T }))
+    if (1)
+L:
+      ;
+  T x;
+}
+
+void
+fn5 (void)
+{
+  while (sizeof (enum { T }))
+    if (1)
+      ;
+    else
+      ;
+  T x;
+}

	Marek