[PATCH] Ignore warning about using different types of enums in switch

[PATCH] Ignore warning about using different types of enums in switch

[Simon Marchi]

When compiling with clang 6, I see a bunch of warnings like this:

/home/emaisin/src/binutils-gdb/gdb/amd64-linux-tdep.c:1427:8: error: comparison of two values with different enumeration types in switch statement ('enum amd64_syscall' and 'amd
64_x32_syscall') [-Werror,-Wenum-compare-switch]
  case amd64_x32_sys_move_pages:
       ^~~~~~~~~~~~~~~~~~~~~~~~

In this switch, we indeed use enumerators of both types
amd64_x32_syscall and amd64_syscall.  This is done on purpose, and the
enum values are chosen so that they are complementary.

I think it's still a useful warning, so I chose to ignore just that
particular case.

gdb/ChangeLog:

	* common/diagnostics.h
	(DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES): New macro.
	* amd64-linux-tdep.c: Use it.
---
 gdb/amd64-linux-tdep.c   | 5 +++++
 gdb/common/diagnostics.h | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index 87f09a4..1817456 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -363,6 +363,9 @@ amd64_all_but_ip_registers_record (struct regcache *regcache)
 static enum gdb_syscall
 amd64_canonicalize_syscall (enum amd64_syscall syscall_number)
 {
+  DIAGNOSTIC_PUSH
+  DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
+
   switch (syscall_number) {
   case amd64_sys_read:
   case amd64_x32_sys_read:
@@ -1430,6 +1433,8 @@ amd64_canonicalize_syscall (enum amd64_syscall syscall_number)
   default:
     return gdb_sys_no_syscall;
   }
+
+  DIAGNOSTIC_POP
 }
 
 /* Parse the arguments of current system call instruction and record
diff --git a/gdb/common/diagnostics.h b/gdb/common/diagnostics.h
index d6ab698..30c0fd6 100644
--- a/gdb/common/diagnostics.h
+++ b/gdb/common/diagnostics.h
@@ -38,6 +38,8 @@
   DIAGNOSTIC_IGNORE ("-Wdeprecated-register")
 # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
   DIAGNOSTIC_IGNORE ("-Wunused-function")
+# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES \
+  DIAGNOSTIC_IGNORE ("-Wenum-compare-switch")
 
 #elif defined (__GNUC__) /* GCC */
 
@@ -45,12 +47,15 @@
 # define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
 # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
   DIAGNOSTIC_IGNORE ("-Wunused-function")
+# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
 
 #else /* Other compilers */
 
 # define DIAGNOSTIC_IGNORE_SELF_MOVE
 # define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
 # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
+# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
+
 #endif
 
 #endif /* COMMON_DIAGNOSTICS_H */
-- 
2.7.4

Re: [PATCH] Ignore warning about using different types of enums in switch

[Simon Marchi]

On 2017-12-12 16:37, Simon Marchi wrote:
> When compiling with clang 6, I see a bunch of warnings like this:
> 
> /home/emaisin/src/binutils-gdb/gdb/amd64-linux-tdep.c:1427:8: error:
> comparison of two values with different enumeration types in switch
> statement ('enum amd64_syscall' and 'amd
> 64_x32_syscall') [-Werror,-Wenum-compare-switch]
>   case amd64_x32_sys_move_pages:
>        ^~~~~~~~~~~~~~~~~~~~~~~~
> 
> In this switch, we indeed use enumerators of both types
> amd64_x32_syscall and amd64_syscall.  This is done on purpose, and the
> enum values are chosen so that they are complementary.
> 
> I think it's still a useful warning, so I chose to ignore just that
> particular case.
> 
> gdb/ChangeLog:
> 
> 	* common/diagnostics.h
> 	(DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES): New macro.
> 	* amd64-linux-tdep.c: Use it.
> ---
>  gdb/amd64-linux-tdep.c   | 5 +++++
>  gdb/common/diagnostics.h | 5 +++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
> index 87f09a4..1817456 100644
> --- a/gdb/amd64-linux-tdep.c
> +++ b/gdb/amd64-linux-tdep.c
> @@ -363,6 +363,9 @@ amd64_all_but_ip_registers_record (struct regcache
> *regcache)
>  static enum gdb_syscall
>  amd64_canonicalize_syscall (enum amd64_syscall syscall_number)
>  {
> +  DIAGNOSTIC_PUSH
> +  DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
> +
>    switch (syscall_number) {
>    case amd64_sys_read:
>    case amd64_x32_sys_read:
> @@ -1430,6 +1433,8 @@ amd64_canonicalize_syscall (enum amd64_syscall
> syscall_number)
>    default:
>      return gdb_sys_no_syscall;
>    }
> +
> +  DIAGNOSTIC_POP
>  }
> 
>  /* Parse the arguments of current system call instruction and record
> diff --git a/gdb/common/diagnostics.h b/gdb/common/diagnostics.h
> index d6ab698..30c0fd6 100644
> --- a/gdb/common/diagnostics.h
> +++ b/gdb/common/diagnostics.h
> @@ -38,6 +38,8 @@
>    DIAGNOSTIC_IGNORE ("-Wdeprecated-register")
>  # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
>    DIAGNOSTIC_IGNORE ("-Wunused-function")
> +# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES \
> +  DIAGNOSTIC_IGNORE ("-Wenum-compare-switch")
> 
>  #elif defined (__GNUC__) /* GCC */
> 
> @@ -45,12 +47,15 @@
>  # define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
>  # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION \
>    DIAGNOSTIC_IGNORE ("-Wunused-function")
> +# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
> 
>  #else /* Other compilers */
> 
>  # define DIAGNOSTIC_IGNORE_SELF_MOVE
>  # define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
>  # define DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
> +# define DIAGNOSTIC_IGNORE_SWITCH_DIFFERENT_ENUM_TYPES
> +
>  #endif
> 
>  #endif /* COMMON_DIAGNOSTICS_H */

I pushed this one.

Simon