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* [1/2] PR 78736: New warning -Wenum-conversion
@ 2017-05-02 17:13 Prathamesh Kulkarni
  2017-05-02 22:10 ` Martin Sebor
  0 siblings, 1 reply; 17+ messages in thread
From: Prathamesh Kulkarni @ 2017-05-02 17:13 UTC (permalink / raw)
  To: gcc Patches, Marek Polacek, Joseph S. Myers

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Hi,
The attached patch attempts to add option -Wenum-conversion for C and
objective-C similar to clang, which warns when an enum value of a type
is implicitly converted to enum value of another type and is enabled
by Wall.

Bootstrapped+tested on x86_64-unknown-linux-gnu.
Is the patch OK for trunk ?

Thanks,
Prathamesh

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2017-05-02  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	* doc/invoke.text: Document Wenum-conversion.
	* c-family/c.opt (Wenum-conversion): New option.
	* c/c-typeck.c (convert_for_assignment): Handle Wenum-conversion.

testsuite/
	* gcc.dg/Wenum-conversion.c: New test-case.

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 9ad2f6e1fcc..e04312ec253 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -492,6 +492,10 @@ Wenum-compare
 C ObjC C++ ObjC++ Var(warn_enum_compare) Init(-1) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
 Warn about comparison of different enum types.
 
+Wenum-conversion
+C ObjC Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C Objc,Wall)
+Warn about implicit conversion of enum types.
+
 Werror
 C ObjC C++ ObjC++
 ; Documented in common.opt
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 6f9909c6396..c9cde8d7fef 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -6309,6 +6309,20 @@ convert_for_assignment (location_t location, location_t expr_loc, tree type,
 	}
     }
 
+  if (warn_enum_conversion)
+    {
+      tree checktype = origtype != NULL_TREE ? origtype : rhstype;
+      if (checktype != error_mark_node
+	  && TREE_CODE (checktype) == ENUMERAL_TYPE
+	  && TREE_CODE (type) == ENUMERAL_TYPE
+	  && TYPE_MAIN_VARIANT (checktype) != TYPE_MAIN_VARIANT (type))
+	{
+	  gcc_rich_location loc (location);
+	  warning_at_rich_loc (&loc, 0, "implicit conversion from"
+			       " enum type of %qT to %qT", checktype, type);
+	}
+    }
+
   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (rhstype))
     return rhs;
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0eeea7b3b87..79b1e175374 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -273,7 +273,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wdisabled-optimization @gol
 -Wno-discarded-qualifiers  -Wno-discarded-array-qualifiers @gol
 -Wno-div-by-zero  -Wdouble-promotion  -Wduplicated-cond @gol
--Wempty-body  -Wenum-compare  -Wno-endif-labels  -Wexpansion-to-defined @gol
+-Wempty-body  -Wenum-compare -Wenum-conversion  -Wno-endif-labels  -Wexpansion-to-defined @gol
 -Werror  -Werror=*  -Wextra-semi  -Wfatal-errors @gol
 -Wfloat-equal  -Wformat  -Wformat=2 @gol
 -Wno-format-contains-nul  -Wno-format-extra-args  @gol
@@ -3754,6 +3754,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
 -Wcomment  @gol
 -Wduplicate-decl-specifier @r{(C and Objective-C only)} @gol
 -Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol
+-Wenum-conversion @r{in C/ObjC;} @gol
 -Wformat   @gol
 -Wint-in-bool-context  @gol
 -Wimplicit @r{(C and Objective-C only)} @gol
@@ -5961,6 +5962,12 @@ In C++ enumerated type mismatches in conditional expressions are also
 diagnosed and the warning is enabled by default.  In C this warning is 
 enabled by @option{-Wall}.
 
+@item -Wenum-conversion @r{(C, Objective-C only)}
+@opindex Wenum-conversion
+@opindex Wno-enum-conversion
+Warn when an enum value of a type is implicitly converted to an enum of
+another type. This warning is enabled by @option{-Wall}.
+
 @item -Wextra-semi @r{(C++, Objective-C++ only)}
 @opindex Wextra-semi
 @opindex Wno-extra-semi
diff --git a/gcc/testsuite/gcc.dg/Wenum-conversion.c b/gcc/testsuite/gcc.dg/Wenum-conversion.c
new file mode 100644
index 00000000000..4459109c7cb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wenum-conversion.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-Wenum-conversion" } */
+
+enum X { x1, x2 };
+enum Y { y1, y2 };
+
+enum X obj = y1;  /* { dg-warning "implicit conversion from enum type of .enum Y. to .enum X." } */
+enum Y obj2 = y1;
+
+enum X obj3;
+void foo()
+{
+  obj3 = y2; /* { dg-warning "implicit conversion from enum type of .enum Y. to .enum X." } */
+}
+
+void bar(enum X);
+void f(void)
+{
+  bar (y1); /* { dg-warning "implicit conversion from enum type of .enum Y. to .enum X." } */
+}

^ permalink raw reply	[flat|nested] 17+ messages in thread

end of thread, other threads:[~2017-09-01 11:55 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-05-02 17:13 [1/2] PR 78736: New warning -Wenum-conversion Prathamesh Kulkarni
2017-05-02 22:10 ` Martin Sebor
2017-05-03  6:10   ` Prathamesh Kulkarni
2017-05-09 13:25     ` Prathamesh Kulkarni
2017-05-09 18:44       ` Martin Sebor
2017-05-09 21:19         ` Pedro Alves
2017-05-10 13:15         ` Prathamesh Kulkarni
2017-05-10 15:18           ` Martin Sebor
2017-06-12 20:17           ` Joseph Myers
2017-07-11 12:29             ` Prathamesh Kulkarni
2017-07-12 15:33               ` Sandra Loosemore
2017-07-31 18:40               ` Prathamesh Kulkarni
2017-08-08  4:21                 ` Prathamesh Kulkarni
2017-08-17 12:53                   ` Prathamesh Kulkarni
2017-08-26 19:27               ` Joseph Myers
2017-09-01  2:37                 ` Prathamesh Kulkarni
2017-09-01 11:55                   ` Joseph Myers

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