[pushed] c++: remove redundant warning [PR100879]

Message ID 20210609004223.1026742-1-jason@redhat.com
State New
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Series
  • [pushed] c++: remove redundant warning [PR100879]
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Commit Message

Jason Merrill via Gcc-patches June 9, 2021, 12:42 a.m.
Before my r277864, build_new_op promoted enums to int before passing them on
to cp_build_binary_op; after that commit, it doesn't, so
warn_for_sign_compare sees the enum operands and gives a redundant warning.
This warning dates back to 1995, and seems to have been dead code for a long
time--likely since build_new_op was added in 1997--so let's just remove it.

Tested x86_64-pc-linux-gnu, applying to trunk.

	PR c++/100879

gcc/c-family/ChangeLog:

	* c-warn.c (warn_for_sign_compare): Remove C++ enum mismatch
	warning.

gcc/testsuite/ChangeLog:

	* g++.dg/diagnostic/enum3.C: New test.
---
 gcc/c-family/c-warn.c                   | 12 ------------
 gcc/testsuite/g++.dg/diagnostic/enum3.C |  9 +++++++++
 2 files changed, 9 insertions(+), 12 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/diagnostic/enum3.C


base-commit: 61fc01806f376a780978a6dea165ec3dadef085b
-- 
2.27.0

Patch

diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
index a587b993fde..cd3c99ef4df 100644
--- a/gcc/c-family/c-warn.c
+++ b/gcc/c-family/c-warn.c
@@ -2240,18 +2240,6 @@  warn_for_sign_compare (location_t location,
   int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
   int unsignedp0, unsignedp1;
 
-  /* In C++, check for comparison of different enum types.  */
-  if (c_dialect_cxx()
-      && TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE
-      && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE
-      && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
-	 != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
-    {
-      warning_at (location,
-		  OPT_Wsign_compare, "comparison between types %qT and %qT",
-		  TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
-    }
-
   /* Do not warn if the comparison is being done in a signed type,
      since the signed type will only be chosen if it can represent
      all the values of the unsigned type.  */
diff --git a/gcc/testsuite/g++.dg/diagnostic/enum3.C b/gcc/testsuite/g++.dg/diagnostic/enum3.C
new file mode 100644
index 00000000000..d51aa8a0f70
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/enum3.C
@@ -0,0 +1,9 @@ 
+// PR c++/100879
+// { dg-additional-options -Werror=sign-compare }
+
+enum e1 { e1val };
+enum e2 { e3val };
+
+int main( int, char * [] ) {
+   if ( e1val == e3val ) return 1; // { dg-warning -Wenum-compare }
+}