diff options
Diffstat (limited to 'gcc/c-family')
| -rw-r--r-- | gcc/c-family/c-common.h | 1 | ||||
| -rw-r--r-- | gcc/c-family/c-warn.c | 32 | ||||
| -rw-r--r-- | gcc/c-family/c.opt | 4 |
3 files changed, 37 insertions, 0 deletions
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h index 849cefab882..078730f1e64 100644 --- a/gcc/c-family/c-common.h +++ b/gcc/c-family/c-common.h @@ -1421,6 +1421,7 @@ extern bool warn_for_restrict (unsigned, tree *, unsigned); extern void warn_for_address_or_pointer_of_packed_member (tree, tree); extern void warn_parm_array_mismatch (location_t, tree, tree); extern void maybe_warn_sizeof_array_div (location_t, tree, tree, tree, tree); +extern void do_warn_array_compare (location_t, tree_code, tree, tree); /* Places where an lvalue, or modifiable lvalue, may be required. Used to select diagnostic messages in lvalue_error and diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c index 84ad6633c96..99cde4a2a59 100644 --- a/gcc/c-family/c-warn.c +++ b/gcc/c-family/c-warn.c @@ -3726,3 +3726,35 @@ maybe_warn_sizeof_array_div (location_t loc, tree arr, tree arr_type, } } } + +/* Warn about C++20 [depr.array.comp] array comparisons: "Equality + and relational comparisons between two operands of array type are + deprecated." We also warn in C and earlier C++ standards. CODE is + the code for this comparison, OP0 and OP1 are the operands. */ + +void +do_warn_array_compare (location_t location, tree_code code, tree op0, tree op1) +{ + STRIP_NOPS (op0); + STRIP_NOPS (op1); + if (TREE_CODE (op0) == ADDR_EXPR) + op0 = TREE_OPERAND (op0, 0); + if (TREE_CODE (op1) == ADDR_EXPR) + op1 = TREE_OPERAND (op1, 0); + + auto_diagnostic_group d; + if (warning_at (location, OPT_Warray_compare, + (c_dialect_cxx () && cxx_dialect >= cxx20) + ? G_("comparison between two arrays is deprecated in C++20") + : G_("comparison between two arrays"))) + { + /* C doesn't allow +arr. */ + if (c_dialect_cxx ()) + inform (location, "use unary %<+%> which decays operands to pointers " + "or %<&%D[0] %s &%D[0]%> to compare the addresses", + op0, op_symbol_code (code), op1); + else + inform (location, "use %<&%D[0] %s &%D[0]%> to compare the addresses", + op0, op_symbol_code (code), op1); + } +} diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 9c151d19870..06457ac739e 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -350,6 +350,10 @@ Warray-bounds= LangEnabledBy(C ObjC C++ LTO ObjC++,Wall,1,0) ; in common.opt +Warray-compare +C ObjC C++ ObjC++ Var(warn_array_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall) +Warn about comparisons between two operands of array type. + Warray-parameter C ObjC C++ ObjC++ Warning Alias(Warray-parameter=, 2, 0) Warn about mismatched declarations of array parameters and unsafe accesses to them. |