* [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885]
@ 2022-08-12 1:38 David Malcolm
2022-08-30 20:18 ` Jason Merrill
2022-08-30 20:40 ` Marek Polacek
0 siblings, 2 replies; 4+ messages in thread
From: David Malcolm @ 2022-08-12 1:38 UTC (permalink / raw)
To: gcc-patches
PR c/90885 notes various places in real-world code where people have
written C/C++ code that uses ^ (exclusive or) where presumbably they
meant exponentiation.
For example
https://codesearch.isocpp.org/cgi-bin/cgi_ppsearch?q=2%5E32&search=Search
currently finds 11 places using "2^32", and all of them appear to be
places where the user means 2 to the power of 32, rather than 2
exclusive-orred with 32 (which is 34).
This patch adds a new -Wxor-used-as-pow warning to the C and C++
frontends to complain about ^ when the left-hand side is the decimal
constant 2 or the decimal constant 10.
This is the same name as the corresponding clang warning:
https://clang.llvm.org/docs/DiagnosticsReference.html#wxor-used-as-pow
As per the clang warning, the warning suggests converting the left-hand
side to a hexadecimal constant if you really mean xor, which suppresses
the warning (and this patch implements a fix-it hint for that, whereas
the clang implementation only has a fix-it hint for the initial
suggestion of exponentiation).
I initially tried implementing this without checking for decimals, but
this version had lots of false positives. Checking for decimals
requires extending the lexer to capture whether or not a CPP_NUMBER
token was decimal. I added a new DECIMAL_INT flag to cpplib.h for this.
Unfortunately, c_token and cp_tokens both have only an unsigned char for
their flags (as captured by c_lex_with_flags), whereas this would add
the 12th flag to cpp_tokens. Of the first 8 flags, all but BOL are used
in the C or C++ frontends, but BOL is not, so I moved that to a higher
position, using its old value for the new DECIMAL_INT flag, so that it
is representable within an unsigned char.
Example output:
demo.c:5:13: warning: result of '2^8' is 10; did you mean '1 << 8' (256)? [-Wxor-used-as-pow]
5 | int t2_8 = 2^8;
| ^
| --
| 1<<
demo.c:5:12: note: you can silence this warning by using a hexadecimal constant (0x2 rather than 2)
5 | int t2_8 = 2^8;
| ^
| 0x2
demo.c:21:15: warning: result of '10^6' is 12; did you mean '1e6'? [-Wxor-used-as-pow]
21 | int t10_6 = 10^6;
| ^
| ---
| 1e
demo.c:21:13: note: you can silence this warning by using a hexadecimal constant (0xa rather than 10)
21 | int t10_6 = 10^6;
| ^~
| 0xa
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
OK for trunk?
Thanks
Dave
gcc/c-family/ChangeLog:
PR c/90885
* c-common.h (check_for_xor_used_as_pow): New decl.
* c-lex.cc (c_lex_with_flags): Add DECIMAL_INT to flags as appropriate.
* c-warn.cc (check_for_xor_used_as_pow): New.
* c.opt (Wxor-used-as-pow): New.
gcc/c/ChangeLog:
PR c/90885
* c-parser.cc (c_parser_string_literal): Clear ret.m_decimal.
(c_parser_expr_no_commas): Likewise.
(c_parser_conditional_expression): Likewise.
(c_parser_binary_expression): Clear m_decimal when popping the
stack.
(c_parser_unary_expression): Clear ret.m_decimal.
(c_parser_has_attribute_expression): Likewise for result.
(c_parser_predefined_identifier): Likewise for expr.
(c_parser_postfix_expression): Likewise for expr.
Set expr.m_decimal when handling a CPP_NUMBER that was a decimal
token.
* c-tree.h (c_expr::m_decimal): New bitfield.
* c-typeck.cc (parser_build_binary_op): Clear result.m_decimal.
(parser_build_binary_op): Call check_for_xor_used_as_pow.
gcc/cp/ChangeLog:
PR c/90885
* cp-tree.h (class cp_expr): Add bitfield m_decimal. Clear it in
existing ctors. Add ctor that allows specifying its value.
(cp_expr::decimal_p): New accessor.
* parser.cc (cp_parser_expression_stack_entry::flags): New field.
(cp_parser_primary_expression): Set m_decimal of cp_expr when
handling numbers.
(cp_parser_binary_expression): Extract flags from token when
populating stack. Call check_for_xor_used_as_pow.
gcc/ChangeLog:
PR c/90885
* doc/invoke.texi (Warning Options): Add -Wxor-used-as-pow.
gcc/testsuite/ChangeLog:
PR c/90885
* c-c++-common/Wxor-used-as-pow-1.c: New test.
* c-c++-common/Wxor-used-as-pow-fixits.c: New test.
* g++.dg/parse/expr3.C: Convert 2 to 0x2 to suppress
-Wxor-used-as-pow.
* g++.dg/warn/Wparentheses-10.C: Likewise.
* g++.dg/warn/Wparentheses-18.C: Likewise.
* g++.dg/warn/Wparentheses-19.C: Likewise.
* g++.dg/warn/Wparentheses-9.C: Likewise.
* g++.dg/warn/Wxor-used-as-pow-named-op.C: New test.
* gcc.dg/Wparentheses-6.c: Convert 2 to 0x2 to suppress
-Wxor-used-as-pow.
* gcc.dg/Wparentheses-7.c: Likewise.
* gcc.dg/precedence-1.c: Likewise.
libcpp/ChangeLog:
PR c/90885
* include/cpplib.h (BOL): Move macro to 1 << 12 since it is
not used by C/C++'s unsigned char token flags.
(DECIMAL_INT): New, using 1 << 6, so that it is visible as
part of C/C++'s 8 bits of token flags.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
---
gcc/c-family/c-common.h | 4 +
gcc/c-family/c-lex.cc | 6 +-
gcc/c-family/c-warn.cc | 94 +++++++++++++++++++
gcc/c-family/c.opt | 4 +
gcc/c/c-parser.cc | 9 ++
gcc/c/c-tree.h | 3 +
gcc/c/c-typeck.cc | 9 ++
gcc/cp/cp-tree.h | 19 +++-
gcc/cp/parser.cc | 17 +++-
gcc/doc/invoke.texi | 15 +++
.../c-c++-common/Wxor-used-as-pow-1.c | 57 +++++++++++
.../c-c++-common/Wxor-used-as-pow-fixits.c | 34 +++++++
gcc/testsuite/g++.dg/parse/expr3.C | 2 +-
gcc/testsuite/g++.dg/warn/Wparentheses-10.C | 14 +--
gcc/testsuite/g++.dg/warn/Wparentheses-18.C | 4 +-
gcc/testsuite/g++.dg/warn/Wparentheses-19.C | 12 +--
gcc/testsuite/g++.dg/warn/Wparentheses-9.C | 4 +-
.../g++.dg/warn/Wxor-used-as-pow-named-op.C | 8 ++
gcc/testsuite/gcc.dg/Wparentheses-6.c | 4 +-
gcc/testsuite/gcc.dg/Wparentheses-7.c | 12 +--
gcc/testsuite/gcc.dg/precedence-1.c | 4 +-
libcpp/include/cpplib.h | 3 +-
22 files changed, 304 insertions(+), 34 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
create mode 100644 gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
create mode 100644 gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index c06769b6f0b..78ce94c6591 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1475,6 +1475,10 @@ extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
extern void warn_for_multistatement_macros (location_t, location_t,
location_t, enum rid);
+extern void check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
+ location_t operator_loc,
+ tree rhs_val);
+
/* In c-attribs.cc. */
extern bool attribute_takes_identifier_p (const_tree);
extern tree handle_deprecated_attribute (tree *, tree, tree, int, bool *);
diff --git a/gcc/c-family/c-lex.cc b/gcc/c-family/c-lex.cc
index 8bfa4f4024f..1eda6f1fccc 100644
--- a/gcc/c-family/c-lex.cc
+++ b/gcc/c-family/c-lex.cc
@@ -509,7 +509,11 @@ c_lex_with_flags (tree *value, location_t *loc, unsigned char *cpp_flags,
/* C++ uses '0' to mark virtual functions as pure.
Set PURE_ZERO to pass this information to the C++ parser. */
if (tok->val.str.len == 1 && *tok->val.str.text == '0')
- add_flags = PURE_ZERO;
+ add_flags = PURE_ZERO | DECIMAL_INT;
+ else if ((flags & CPP_N_INTEGER) && (flags & CPP_N_DECIMAL))
+ /* -Wxor-used-as-pow is only active for LHS of ^ expressed
+ as a decimal integer. */
+ add_flags = DECIMAL_INT;
*value = interpret_integer (tok, flags, &overflow);
break;
diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
index ea7335f3edf..ed79cc3ca40 100644
--- a/gcc/c-family/c-warn.cc
+++ b/gcc/c-family/c-warn.cc
@@ -3799,3 +3799,97 @@ do_warn_array_compare (location_t location, tree_code code, tree op0, tree op1)
op0, op_symbol_code (code), op1);
}
}
+
+/* Given LHS_VAL ^ RHS_VAL, where LHS_LOC is the location of the LHS and
+ OPERATOR_LOC is the location of the ^, complain with -Wxor-used-as-pow
+ if it looks like the user meant exponentiation rather than xor. */
+
+void
+check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
+ location_t operator_loc,
+ tree rhs_val)
+{
+ /* Only complain if both args are non-negative integer constants. */
+ if (!(TREE_CODE (lhs_val) == INTEGER_CST
+ && tree_int_cst_sgn (lhs_val) >= 0))
+ return;
+ if (!(TREE_CODE (rhs_val) == INTEGER_CST
+ && tree_int_cst_sgn (rhs_val) >= 0))
+ return;
+
+ /* Only complain if the LHS is 2 or 10. */
+ unsigned HOST_WIDE_INT lhs_uhwi = tree_to_uhwi (lhs_val);
+ if (lhs_uhwi != 2 && lhs_uhwi != 10)
+ return;
+
+ unsigned HOST_WIDE_INT rhs_uhwi = tree_to_uhwi (rhs_val);
+ unsigned HOST_WIDE_INT xor_result = lhs_uhwi ^ rhs_uhwi;
+ binary_op_rich_location loc (operator_loc,
+ lhs_val, rhs_val, false);
+
+ /* If we issue fix-it hints with the warning then we will also issue a
+ note suggesting how to suppress the warning with a different change.
+ These proposed changes are incompatible. */
+ loc.fixits_cannot_be_auto_applied ();
+
+ auto_diagnostic_group d;
+ bool warned = false;
+ if (lhs_uhwi == 2)
+ {
+ /* Would exponentiation fit in int, in long long, or not at all? */
+ if (rhs_uhwi < (INT_TYPE_SIZE - 1))
+ {
+ unsigned HOST_WIDE_INT suggested_result = 1 << rhs_uhwi;
+ loc.add_fixit_replace (lhs_loc, "1");
+ loc.add_fixit_replace (operator_loc, "<<");
+ warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+ "result of %<%wu^%wu%> is %wu;"
+ " did you mean %<1 << %wu%> (%wu)?",
+ lhs_uhwi, rhs_uhwi, xor_result,
+ rhs_uhwi, suggested_result);
+ }
+ else if (rhs_uhwi < (LONG_LONG_TYPE_SIZE - 1))
+ {
+ loc.add_fixit_replace (lhs_loc, "1LL");
+ loc.add_fixit_replace (operator_loc, "<<");
+ warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+ "result of %<%wu^%wu%> is %wu;"
+ " did you mean %<1LL << %wu%>?",
+ lhs_uhwi, rhs_uhwi, xor_result,
+ rhs_uhwi);
+ }
+ else if (rhs_uhwi <= LONG_LONG_TYPE_SIZE)
+ warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+ "result of %<%wu^%wu%> is %wu;"
+ " did you mean exponentiation?",
+ lhs_uhwi, rhs_uhwi, xor_result);
+ /* Otherwise assume it's an xor. */
+ }
+ else
+ {
+ gcc_assert (lhs_uhwi == 10);
+ loc.add_fixit_replace (lhs_loc, "1");
+ loc.add_fixit_replace (operator_loc, "e");
+ warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+ "result of %<%wu^%wu%> is %wu;"
+ " did you mean %<1e%wu%>?",
+ lhs_uhwi, rhs_uhwi, xor_result,
+ rhs_uhwi);
+ }
+ if (warned)
+ {
+ gcc_rich_location note_loc (lhs_loc);
+ if (lhs_uhwi == 2)
+ note_loc.add_fixit_replace (lhs_loc, "0x2");
+ else
+ {
+ gcc_assert (lhs_uhwi == 10);
+ note_loc.add_fixit_replace (lhs_loc, "0xa");
+ }
+ note_loc.fixits_cannot_be_auto_applied ();
+ inform (¬e_loc,
+ "you can silence this warning by using a hexadecimal constant"
+ " (%wx rather than %wd)",
+ lhs_uhwi, lhs_uhwi);
+ }
+}
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 44e1a60ce24..c11ea50ac42 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1439,6 +1439,10 @@ Wwrite-strings
C ObjC C++ ObjC++ Var(warn_write_strings) Warning
In C++, nonzero means warn about deprecated conversion from string literals to 'char *'. In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
+Wxor-used-as-pow
+C C++ Common Var(warn_xor_used_as_pow) Warning Init(1)
+Warn about xor operators where it appears the user meant exponentiation.
+
Wzero-as-null-pointer-constant
C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
Warn when a literal '0' is used as null pointer.
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 92049d1a101..25064576829 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -7496,6 +7496,7 @@ c_parser_string_literal (c_parser *parser, bool translate, bool wide_ok)
ret.original_code = STRING_CST;
ret.original_type = NULL_TREE;
set_c_expr_source_range (&ret, get_range_from_loc (line_table, loc));
+ ret.m_decimal = 0;
parser->seen_string_literal = true;
return ret;
}
@@ -7575,6 +7576,7 @@ c_parser_expr_no_commas (c_parser *parser, struct c_expr *after,
ret.value = build_modify_expr (op_location, lhs.value, lhs.original_type,
code, exp_location, rhs.value,
rhs.original_type);
+ ret.m_decimal = 0;
set_c_expr_source_range (&ret, lhs.get_start (), rhs.get_finish ());
if (code == NOP_EXPR)
ret.original_code = MODIFY_EXPR;
@@ -7712,6 +7714,7 @@ c_parser_conditional_expression (c_parser *parser, struct c_expr *after,
: NULL);
}
set_c_expr_source_range (&ret, start, exp2.get_finish ());
+ ret.m_decimal = 0;
return ret;
}
@@ -7901,6 +7904,7 @@ c_parser_binary_expression (c_parser *parser, struct c_expr *after,
TREE_OPERAND (t, 0) = stack[0].expr.value; \
TREE_OPERAND (t, 1) = stack[1].expr.value; \
stack[0].expr.value = t; \
+ stack[0].expr.m_decimal = 0; \
} \
else \
stack[sp - 1].expr = parser_build_binary_op (stack[sp].loc, \
@@ -8187,6 +8191,7 @@ c_parser_unary_expression (c_parser *parser)
ret.value = build_indirect_ref (combined_loc, op.value, RO_UNARY_STAR);
ret.src_range.m_start = op_loc;
ret.src_range.m_finish = finish;
+ ret.m_decimal = 0;
return ret;
}
case CPP_PLUS:
@@ -8560,6 +8565,7 @@ c_parser_has_attribute_expression (c_parser *parser)
result.value = boolean_false_node;
set_c_expr_source_range (&result, start, finish);
+ result.m_decimal = 0;
return result;
}
@@ -8925,6 +8931,7 @@ c_parser_predefined_identifier (c_parser *parser)
expr.value = fname_decl (loc, c_parser_peek_token (parser)->keyword,
c_parser_peek_token (parser)->value);
set_c_expr_source_range (&expr, loc, loc);
+ expr.m_decimal = 0;
c_parser_consume_token (parser);
return expr;
}
@@ -9003,12 +9010,14 @@ c_parser_postfix_expression (c_parser *parser)
source_range tok_range = c_parser_peek_token (parser)->get_range ();
expr.original_code = ERROR_MARK;
expr.original_type = NULL;
+ expr.m_decimal = 0;
switch (c_parser_peek_token (parser)->type)
{
case CPP_NUMBER:
expr.value = c_parser_peek_token (parser)->value;
set_c_expr_source_range (&expr, tok_range);
loc = c_parser_peek_token (parser)->location;
+ expr.m_decimal = c_parser_peek_token (parser)->flags & DECIMAL_INT;
c_parser_consume_token (parser);
if (TREE_CODE (expr.value) == FIXED_CST
&& !targetm.fixed_point_supported_p ())
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index e655afd1cd4..b4231a17859 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -147,6 +147,9 @@ struct c_expr
etc), so we stash a copy here. */
source_range src_range;
+ /* True if this was directly from a decimal constant token. */
+ bool m_decimal : 1;
+
/* Access to the first and last locations within the source spelling
of this expression. */
location_t get_start () const { return src_range.m_start; }
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 8514488b7a5..1f5fa07c925 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -3821,6 +3821,7 @@ parser_build_binary_op (location_t location, enum tree_code code,
struct c_expr arg1, struct c_expr arg2)
{
struct c_expr result;
+ result.m_decimal = 0;
enum tree_code code1 = arg1.original_code;
enum tree_code code2 = arg2.original_code;
@@ -3978,6 +3979,14 @@ parser_build_binary_op (location_t location, enum tree_code code,
"comparison between %qT and %qT",
type1, type2);
+ if (warn_xor_used_as_pow
+ && code == BIT_XOR_EXPR
+ && arg1.m_decimal
+ && arg2.m_decimal)
+ check_for_xor_used_as_pow (arg1.get_location (), arg1.value,
+ location,
+ arg2.value);
+
return result;
}
\f
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 3278b4114bd..cdff8282e64 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -54,13 +54,23 @@ class cp_expr
{
public:
cp_expr () :
- m_value (NULL), m_loc (UNKNOWN_LOCATION) {}
+ m_value (NULL), m_loc (UNKNOWN_LOCATION),
+ m_decimal (false)
+ {}
cp_expr (tree value) :
- m_value (value), m_loc (cp_expr_location (m_value)) {}
+ m_value (value), m_loc (cp_expr_location (m_value)),
+ m_decimal (false)
+ {}
cp_expr (tree value, location_t loc):
- m_value (value), m_loc (loc)
+ m_value (value), m_loc (loc), m_decimal (false)
+ {
+ protected_set_expr_location (value, loc);
+ }
+
+ cp_expr (tree value, location_t loc, bool decimal):
+ m_value (value), m_loc (loc), m_decimal (decimal)
{
protected_set_expr_location (value, loc);
}
@@ -102,9 +112,12 @@ public:
return *this;
}
+ bool decimal_p () const { return m_decimal; }
+
private:
tree m_value;
location_t m_loc;
+ bool m_decimal : 1;
};
inline bool
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 33926d23179..73c46e79979 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -2066,6 +2066,8 @@ struct cp_parser_expression_stack_entry
enum cp_parser_prec prec;
/* Location of the binary operation we are parsing. */
location_t loc;
+ /* Flags from the operator token. */
+ unsigned char flags;
};
/* The stack for storing partial expressions. We only need NUM_PREC_VALUES
@@ -5611,7 +5613,7 @@ cp_parser_primary_expression (cp_parser *parser,
if (!cast_p)
cp_parser_non_integral_constant_expression (parser, NIC_FLOAT);
}
- return (cp_expr (token->u.value, token->location)
+ return (cp_expr (token->u.value, token->location, token->flags & DECIMAL_INT)
.maybe_add_location_wrapper ());
case CPP_CHAR_USERDEF:
@@ -10157,6 +10159,7 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
get_rhs:
current.tree_type = binops_by_token[token->type].tree_type;
current.loc = token->location;
+ current.flags = token->flags;
/* We used the operator token. */
cp_lexer_consume_token (parser->lexer);
@@ -10241,6 +10244,18 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
warn_logical_not_parentheses (current.loc, current.tree_type,
current.lhs, maybe_constant_value (rhs));
+ if (warn_xor_used_as_pow
+ && current.tree_type == BIT_XOR_EXPR
+ /* Don't warn for named "xor" (as opposed to '^'). */
+ && !(current.flags & NAMED_OP)
+ && current.lhs.decimal_p ()
+ && rhs.decimal_p ())
+ check_for_xor_used_as_pow
+ (current.lhs.get_location (),
+ tree_strip_any_location_wrapper (current.lhs),
+ current.loc,
+ tree_strip_any_location_wrapper (rhs));
+
overload = NULL;
location_t combined_loc = make_location (current.loc,
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index a17c059d515..31516ded123 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -414,6 +414,7 @@ Objective-C and Objective-C++ Dialects}.
-Wvector-operation-performance @gol
-Wvla -Wvla-larger-than=@var{byte-size} -Wno-vla-larger-than @gol
-Wvolatile-register-var -Wwrite-strings @gol
+-Wxor-used-as-pow @gol
-Wzero-length-bounds}
@item Static Analyzer Options
@@ -9661,6 +9662,20 @@ modifier does not inhibit all optimizations that may eliminate reads
and/or writes to register variables. This warning is enabled by
@option{-Wall}.
+@item -Wxor-used-as-pow @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wxor-used-as-pow
+@opindex Wno-xor-used-as-pow
+Warn about uses of @code{^}, the exclusive or operator, where it appears
+the user meant exponentiation. Specifically, the warning occurs when the
+left-hand side is the decimal constant 2 or 10 and the right-hand side
+is also a decimal constant.
+
+In C and C++, @code{^} means exclusive or, whereas in some other languages
+(e.g. TeX and some versions of BASIC) it means exponentiation.
+
+This warning is enabled by default. It can be silenced by converting one
+of the operands to hexadecimal.
+
@item -Wdisabled-optimization
@opindex Wdisabled-optimization
@opindex Wno-disabled-optimization
diff --git a/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
new file mode 100644
index 00000000000..962902c3a05
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
@@ -0,0 +1,57 @@
+/* The precise output depends of sizeof(int) and sizeof(long long), so
+ filter by target. */
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+
+/* Apparent uses of ^ for powers of 2. */
+
+short t2_16 = 2^16; /* { dg-warning "result of '2\\^16' is 18; did you mean '1 << 16' \\(65536\\)\\? \\\[-Wxor-used-as-pow\\\]" } */
+int t2_17 = 2^17; /* { dg-warning "result of '2\\^17' is 19; did you mean '1 << 17' \\(131072\\)\\?" } */
+int t2_30 = 2^30; /* { dg-warning "result of '2\\^30' is 28; did you mean '1 << 30' \\(1073741824\\)\\?" } */
+
+/* Should be 1LL at 31 and above, due to overflow. */
+int t2_31 = 2^31; /* { dg-warning "result of '2\\^31' is 29; did you mean '1LL << 31'\\?" } */
+int t2_32 = 2^32; /* { dg-warning "result of '2\\^32' is 34; did you mean '1LL << 32'\\?" } */
+
+long t2_63 = 2^63; /* { dg-warning "result of '2\\^63' is 61; did you mean exponentiation\\?" } */
+long t2_64 = 2^64; /* { dg-warning "result of '2\\^64' is 66; did you mean exponentiation\\?" } */
+
+/* ...but don't warn when RHS is large enough. */
+long t2_65 = 2^65;
+long t2_127 = 2^127;
+long t2_128 = 2^128;
+long t2_129 = 2^129;
+
+/* Verify that -Wxor-used-as-pow happens before folding. */
+long t2_32_m1 = ((2^32)-1); /* { dg-warning "result of '2\\^32' is 34; did you mean '1LL << 32'\\?" } */
+
+
+/* Apparent uses of ^ for powers of 10. */
+
+long t10_2 = 10^2; /* { dg-warning "result of '10\\^2' is 8; did you mean '1e2'\\?" } */
+long t10_9 = 10^9; /* { dg-warning "result of '10\\^9' is 3; did you mean '1e9'\\?" } */
+long t10_10 = 10^10; /* { dg-warning "result of '10\\^10' is 0; did you mean '1e10'\\?" } */
+long t10_100 = 10^100; /* { dg-warning "result of '10\\^100' is 110; did you mean '1e100'\\?" } */
+
+/* Don't warn on negatives. */
+long tm2_2 = -2^2;
+long t2_m2 = 2^-2;
+long tm10_10 = -10^10;
+long t10_m10 = 10^-10;
+
+/* If LHS is not 2 or 10, we shouldn't complain. */
+int t0_0 = 0 ^ 0;
+int t6_7 = 6 ^ 7;
+
+/* Floating point is already covered by type-checking. */
+float f10_10 = 10.f^10; /* { dg-error "invalid operands to binary \\^ \\(have 'float' and 'int'\\)" "" { target c } } */
+/* { dg-error "invalid operands of types 'float' and 'int' to binary 'operator\\^'" "" { target c++ } .-1 } */
+
+/* Don't complain if the LHS isn't literal decimal 2 or 10. */
+int t1p1_16 = (1 + 1) ^ 16;
+int t5p5_6 = (5 + 5) ^ 6;
+int h2_8 = 0x2 ^ 8;
+int h10_3 = 0xa ^ 3;
+
+/* Don't complain if the RHS isn't literal decimal. */
+int t2_x16 = 2^0x10;
+int h10_x3 = 10 ^ 0x3;
diff --git a/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
new file mode 100644
index 00000000000..f612b761c30
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
@@ -0,0 +1,34 @@
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+/* Test fixit hints for -Wxor-used-as-pow. */
+
+int t2_8 = 2^8; /* { dg-line line_a } */
+/* { dg-warning "result of '2\\^8' is 10; did you mean '1 << 8' \\(256\\)\\?" "warn" { target *-*-* } line_a } */
+/* { dg-begin-multiline-output "" }
+ int t2_8 = 2^8;
+ ^
+ --
+ 1<<
+ { dg-end-multiline-output "" } */
+/* { dg-message "you can silence this warning by using a hexadecimal constant \\(0x2 rather than 2\\)" "note" { target *-*-* } line_a } */
+/* { dg-begin-multiline-output "" }
+ int t2_8 = 2^8;
+ ^
+ 0x2
+ { dg-end-multiline-output "" } */
+
+
+int t10_6 = 10^6; /* { dg-line line_b } */
+/* { dg-warning "result of '10\\^6' is 12; did you mean '1e6'\\?" "warn" { target *-*-* } line_b } */
+/* { dg-begin-multiline-output "" }
+ int t10_6 = 10^6;
+ ^
+ ---
+ 1e
+ { dg-end-multiline-output "" } */
+/* { dg-message "you can silence this warning by using a hexadecimal constant \\(0xa rather than 10\\)" "note" { target *-*-* } line_b } */
+/* { dg-begin-multiline-output "" }
+ int t10_6 = 10^6;
+ ^~
+ 0xa
+ { dg-end-multiline-output "" } */
diff --git a/gcc/testsuite/g++.dg/parse/expr3.C b/gcc/testsuite/g++.dg/parse/expr3.C
index 95d332f41b0..1e166733843 100644
--- a/gcc/testsuite/g++.dg/parse/expr3.C
+++ b/gcc/testsuite/g++.dg/parse/expr3.C
@@ -23,7 +23,7 @@
test (||, &&, 1, 1, 0, 0)
test (&&, |, 5, 1, 1, 19)
-test (|, ^, 1, 2, 2, 1)
+test (|, ^, 1, 2, 0x2, 1)
test (^, &, 1, 3, 2, 6)
test (&, ==, 1, 3, 2, 0)
test (==, <, 2, 0, 0, 0)
diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-10.C b/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
index 557db091ad0..a5d28efcc2e 100644
--- a/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
@@ -16,7 +16,7 @@ bar (int a, int b, int c)
foo (1 & (2 ^ c));
foo (1 & 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 & 2) ^ 3);
- foo (1 & (2 ^ 3));
+ foo (1 & (0x2 ^ 3));
foo (a ^ b & c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) & c);
foo (a ^ (b & c));
@@ -34,7 +34,7 @@ bar (int a, int b, int c)
foo (1 + (2 ^ c));
foo (1 + 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 + 2) ^ 3);
- foo (1 + (2 ^ 3));
+ foo (1 + (0x2 ^ 3));
foo (a ^ b + c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) + c);
foo (a ^ (b + c));
@@ -52,7 +52,7 @@ bar (int a, int b, int c)
foo (1 - (2 ^ c));
foo (1 - 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 - 2) ^ 3);
- foo (1 - (2 ^ 3));
+ foo (1 - (0x2 ^ 3));
foo (a ^ b - c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) - c);
foo (a ^ (b - c));
@@ -70,7 +70,7 @@ bar (int a, int b, int c)
foo (1 >= (2 ^ c));
foo (1 >= 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 >= 2) ^ 3);
- foo (1 >= (2 ^ 3));
+ foo (1 >= (0x2 ^ 3));
foo (a ^ b >= c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) >= c);
foo (a ^ (b >= c));
@@ -88,7 +88,7 @@ bar (int a, int b, int c)
foo (1 == (2 ^ c));
foo (1 == 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 == 2) ^ 3);
- foo (1 == (2 ^ 3));
+ foo (1 == (0x2 ^ 3));
foo (a ^ b == c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) == c);
foo (a ^ (b == c));
@@ -104,9 +104,9 @@ bar (int a, int b, int c)
foo (1 < 2 ^ c); // { dg-warning "parentheses" "correct warning" }
foo ((1 < 2) ^ c);
foo (1 < (2 ^ c));
- foo (1 < 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
+ foo (1 < 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 < 2) ^ 3);
- foo (1 < (2 ^ 3));
+ foo (1 < (0x2 ^ 3));
foo (a ^ b < c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) < c);
foo (a ^ (b < c));
diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-18.C b/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
index 83efaff4189..d50fad8ae80 100644
--- a/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
@@ -42,9 +42,9 @@ bar (T a, T b, T c)
foo (1 | 2 ^ c); // { dg-warning "parentheses" "correct warning" }
foo ((1 | 2) ^ c);
foo (1 | (2 ^ c));
- foo (1 | 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
+ foo (1 | 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 | 2) ^ 3);
- foo (1 | (2 ^ 3));
+ foo (1 | (0x2 ^ 3));
foo (a + b | c); // { dg-warning "parentheses" "correct warning" }
foo ((a + b) | c);
foo (a + (b | c));
diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-19.C b/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
index f0e2b805c9e..2ad8036ac84 100644
--- a/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
@@ -17,7 +17,7 @@ bar (T a, T b, T c)
foo (1 & (2 ^ c));
foo (1 & 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 & 2) ^ 3);
- foo (1 & (2 ^ 3));
+ foo (1 & (0x2 ^ 3));
foo (a ^ b & c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) & c);
foo (a ^ (b & c));
@@ -35,7 +35,7 @@ bar (T a, T b, T c)
foo (1 + (2 ^ c));
foo (1 + 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 + 2) ^ 3);
- foo (1 + (2 ^ 3));
+ foo (1 + (0x2 ^ 3));
foo (a ^ b + c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) + c);
foo (a ^ (b + c));
@@ -53,7 +53,7 @@ bar (T a, T b, T c)
foo (1 - (2 ^ c));
foo (1 - 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 - 2) ^ 3);
- foo (1 - (2 ^ 3));
+ foo (1 - (0x2 ^ 3));
foo (a ^ b - c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) - c);
foo (a ^ (b - c));
@@ -71,7 +71,7 @@ bar (T a, T b, T c)
foo (1 >= (2 ^ c));
foo (1 >= 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 >= 2) ^ 3);
- foo (1 >= (2 ^ 3));
+ foo (1 >= (0x2 ^ 3));
foo (a ^ b >= c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) >= c);
foo (a ^ (b >= c));
@@ -89,7 +89,7 @@ bar (T a, T b, T c)
foo (1 == (2 ^ c));
foo (1 == 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 == 2) ^ 3);
- foo (1 == (2 ^ 3));
+ foo (1 == (0x2 ^ 3));
foo (a ^ b == c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) == c);
foo (a ^ (b == c));
@@ -107,7 +107,7 @@ bar (T a, T b, T c)
foo (1 < (2 ^ c));
foo (1 < 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 < 2) ^ 3);
- foo (1 < (2 ^ 3));
+ foo (1 < (0x2 ^ 3));
foo (a ^ b < c); // { dg-warning "parentheses" "correct warning" }
foo ((a ^ b) < c);
foo (a ^ (b < c));
diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-9.C b/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
index 7c8f01d327b..69976b3bacf 100644
--- a/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
@@ -41,9 +41,9 @@ bar (int a, int b, int c)
foo (1 | 2 ^ c); // { dg-warning "parentheses" "correct warning" }
foo ((1 | 2) ^ c);
foo (1 | (2 ^ c));
- foo (1 | 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
+ foo (1 | 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
foo ((1 | 2) ^ 3);
- foo (1 | (2 ^ 3));
+ foo (1 | (0x2 ^ 3));
foo (a + b | c); // { dg-warning "parentheses" "correct warning" }
foo ((a + b) | c);
foo (a + (b | c));
diff --git a/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C b/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
new file mode 100644
index 00000000000..4899d72b11b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
@@ -0,0 +1,8 @@
+/* Verify that -Wxor-used-as-pow only warns with ^ and not with
+ named "xor". */
+
+int t2_16 = 2^16; /* { dg-warning "result of '2\\^16' is 18; did you mean '1 << 16' \\(65536\\)\\?" } */
+int t2x16 = 2 xor 16;
+
+int t10_6 = 10^6; /* { dg-warning "result of '10\\^6' is 12; did you mean '1e6'\\?" } */
+int t10x6 = 10 xor 6;
diff --git a/gcc/testsuite/gcc.dg/Wparentheses-6.c b/gcc/testsuite/gcc.dg/Wparentheses-6.c
index 2d2cc161394..260b6adebea 100644
--- a/gcc/testsuite/gcc.dg/Wparentheses-6.c
+++ b/gcc/testsuite/gcc.dg/Wparentheses-6.c
@@ -43,9 +43,9 @@ bar (int a, int b, int c)
foo (1 | 2 ^ c); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 | 2) ^ c);
foo (1 | (2 ^ c));
- foo (1 | 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
+ foo (1 | 0x2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 | 2) ^ 3);
- foo (1 | (2 ^ 3));
+ foo (1 | (0x2 ^ 3));
foo (a + b | c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a + b) | c);
foo (a + (b | c));
diff --git a/gcc/testsuite/gcc.dg/Wparentheses-7.c b/gcc/testsuite/gcc.dg/Wparentheses-7.c
index f3516969d23..6805094d296 100644
--- a/gcc/testsuite/gcc.dg/Wparentheses-7.c
+++ b/gcc/testsuite/gcc.dg/Wparentheses-7.c
@@ -18,7 +18,7 @@ bar (int a, int b, int c)
foo (1 & (2 ^ c));
foo (1 & 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 & 2) ^ 3);
- foo (1 & (2 ^ 3));
+ foo (1 & (0x2 ^ 3));
foo (a ^ b & c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) & c);
foo (a ^ (b & c));
@@ -36,7 +36,7 @@ bar (int a, int b, int c)
foo (1 + (2 ^ c));
foo (1 + 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 + 2) ^ 3);
- foo (1 + (2 ^ 3));
+ foo (1 + (0x2 ^ 3));
foo (a ^ b + c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) + c);
foo (a ^ (b + c));
@@ -54,7 +54,7 @@ bar (int a, int b, int c)
foo (1 - (2 ^ c));
foo (1 - 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 - 2) ^ 3);
- foo (1 - (2 ^ 3));
+ foo (1 - (0x2 ^ 3));
foo (a ^ b - c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) - c);
foo (a ^ (b - c));
@@ -72,7 +72,7 @@ bar (int a, int b, int c)
foo (1 >= (2 ^ c));
foo (1 >= 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 >= 2) ^ 3);
- foo (1 >= (2 ^ 3));
+ foo (1 >= (0x2 ^ 3));
foo (a ^ b >= c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) >= c);
foo (a ^ (b >= c));
@@ -90,7 +90,7 @@ bar (int a, int b, int c)
foo (1 == (2 ^ c));
foo (1 == 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 == 2) ^ 3);
- foo (1 == (2 ^ 3));
+ foo (1 == (0x2 ^ 3));
foo (a ^ b == c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) == c);
foo (a ^ (b == c));
@@ -108,7 +108,7 @@ bar (int a, int b, int c)
foo (1 < (2 ^ c));
foo (1 < 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
foo ((1 < 2) ^ 3);
- foo (1 < (2 ^ 3));
+ foo (1 < (0x2 ^ 3));
foo (a ^ b < c); /* { dg-warning "parentheses" "correct warning" } */
foo ((a ^ b) < c);
foo (a ^ (b < c));
diff --git a/gcc/testsuite/gcc.dg/precedence-1.c b/gcc/testsuite/gcc.dg/precedence-1.c
index f3f1e352708..089cdfc1472 100644
--- a/gcc/testsuite/gcc.dg/precedence-1.c
+++ b/gcc/testsuite/gcc.dg/precedence-1.c
@@ -135,10 +135,10 @@ f (void)
ASSERT_BIN (0, !=, 2, &, 1, 1, 1, 0);
ASSERT_BIN (1, &, 2, ==, 0, 0, 1, 0);
ASSERT_BIN (1, &, 2, !=, 0, 1, 0, 1);
- ASSERT_BIN (1, &, 2, ^, 3, 3, 3, 1);
+ ASSERT_BIN (1, &, 0x2, ^, 3, 3, 3, 1);
ASSERT_BIN (3, ^, 2, &, 1, 3, 1, 3);
ASSERT_BIN (3, ^, 2, |, 1, 1, 1, 0);
- ASSERT_BIN (3, |, 2, ^, 1, 3, 2, 3);
+ ASSERT_BIN (3, |, 0x2, ^, 1, 3, 2, 3);
ASSERT_BIN (2, |, 0, &&, 2, 1, 1, 2);
ASSERT_BIN (2, &&, 0, |, 2, 1, 2, 1);
ASSERT_BIN (0, &&, 0, ||, 1, 1, 1, 0);
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 3eba6f74b57..f1e7c2b3b2a 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -190,7 +190,7 @@ struct GTY(()) cpp_string {
#define NAMED_OP (1 << 4) /* C++ named operators. */
#define PREV_FALLTHROUGH (1 << 5) /* On a token preceeded by FALLTHROUGH
comment. */
-#define BOL (1 << 6) /* Token at beginning of line. */
+#define DECIMAL_INT (1 << 6) /* Decimal integer, set in c-lex.cc. */
#define PURE_ZERO (1 << 7) /* Single 0 digit, used by the C++ frontend,
set in c-lex.cc. */
#define SP_DIGRAPH (1 << 8) /* # or ## token was a digraph. */
@@ -199,6 +199,7 @@ struct GTY(()) cpp_string {
after a # operator. */
#define NO_EXPAND (1 << 10) /* Do not macro-expand this token. */
#define PRAGMA_OP (1 << 11) /* _Pragma token. */
+#define BOL (1 << 12) /* Token at beginning of line. */
/* Specify which field, if any, of the cpp_token union is used. */
--
2.26.3
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885]
2022-08-12 1:38 [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885] David Malcolm
@ 2022-08-30 20:18 ` Jason Merrill
2022-08-30 20:40 ` Marek Polacek
1 sibling, 0 replies; 4+ messages in thread
From: Jason Merrill @ 2022-08-30 20:18 UTC (permalink / raw)
To: David Malcolm, gcc-patches
On 8/11/22 21:38, David Malcolm via Gcc-patches wrote:
> PR c/90885 notes various places in real-world code where people have
> written C/C++ code that uses ^ (exclusive or) where presumbably they
> meant exponentiation.
>
> For example
> https://codesearch.isocpp.org/cgi-bin/cgi_ppsearch?q=2%5E32&search=Search
> currently finds 11 places using "2^32", and all of them appear to be
> places where the user means 2 to the power of 32, rather than 2
> exclusive-orred with 32 (which is 34).
>
> This patch adds a new -Wxor-used-as-pow warning to the C and C++
> frontends to complain about ^ when the left-hand side is the decimal
> constant 2 or the decimal constant 10.
>
> This is the same name as the corresponding clang warning:
> https://clang.llvm.org/docs/DiagnosticsReference.html#wxor-used-as-pow
>
> As per the clang warning, the warning suggests converting the left-hand
> side to a hexadecimal constant if you really mean xor, which suppresses
> the warning (and this patch implements a fix-it hint for that, whereas
> the clang implementation only has a fix-it hint for the initial
> suggestion of exponentiation).
>
> I initially tried implementing this without checking for decimals, but
> this version had lots of false positives. Checking for decimals
> requires extending the lexer to capture whether or not a CPP_NUMBER
> token was decimal. I added a new DECIMAL_INT flag to cpplib.h for this.
> Unfortunately, c_token and cp_tokens both have only an unsigned char for
> their flags (as captured by c_lex_with_flags), whereas this would add
> the 12th flag to cpp_tokens. Of the first 8 flags, all but BOL are used
> in the C or C++ frontends, but BOL is not, so I moved that to a higher
> position, using its old value for the new DECIMAL_INT flag, so that it
> is representable within an unsigned char.
>
> Example output:
>
> demo.c:5:13: warning: result of '2^8' is 10; did you mean '1 << 8' (256)? [-Wxor-used-as-pow]
> 5 | int t2_8 = 2^8;
> | ^
> | --
> | 1<<
> demo.c:5:12: note: you can silence this warning by using a hexadecimal constant (0x2 rather than 2)
> 5 | int t2_8 = 2^8;
> | ^
> | 0x2
> demo.c:21:15: warning: result of '10^6' is 12; did you mean '1e6'? [-Wxor-used-as-pow]
> 21 | int t10_6 = 10^6;
> | ^
> | ---
> | 1e
> demo.c:21:13: note: you can silence this warning by using a hexadecimal constant (0xa rather than 10)
> 21 | int t10_6 = 10^6;
> | ^~
> | 0xa
>
> Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
>
> OK for trunk?
Looks good to me, but a C maintainer should sign off on the C front-end
changes.
> Thanks
> Dave
>
>
> gcc/c-family/ChangeLog:
> PR c/90885
> * c-common.h (check_for_xor_used_as_pow): New decl.
> * c-lex.cc (c_lex_with_flags): Add DECIMAL_INT to flags as appropriate.
> * c-warn.cc (check_for_xor_used_as_pow): New.
> * c.opt (Wxor-used-as-pow): New.
>
> gcc/c/ChangeLog:
> PR c/90885
> * c-parser.cc (c_parser_string_literal): Clear ret.m_decimal.
> (c_parser_expr_no_commas): Likewise.
> (c_parser_conditional_expression): Likewise.
> (c_parser_binary_expression): Clear m_decimal when popping the
> stack.
> (c_parser_unary_expression): Clear ret.m_decimal.
> (c_parser_has_attribute_expression): Likewise for result.
> (c_parser_predefined_identifier): Likewise for expr.
> (c_parser_postfix_expression): Likewise for expr.
> Set expr.m_decimal when handling a CPP_NUMBER that was a decimal
> token.
> * c-tree.h (c_expr::m_decimal): New bitfield.
> * c-typeck.cc (parser_build_binary_op): Clear result.m_decimal.
> (parser_build_binary_op): Call check_for_xor_used_as_pow.
>
> gcc/cp/ChangeLog:
> PR c/90885
> * cp-tree.h (class cp_expr): Add bitfield m_decimal. Clear it in
> existing ctors. Add ctor that allows specifying its value.
> (cp_expr::decimal_p): New accessor.
> * parser.cc (cp_parser_expression_stack_entry::flags): New field.
> (cp_parser_primary_expression): Set m_decimal of cp_expr when
> handling numbers.
> (cp_parser_binary_expression): Extract flags from token when
> populating stack. Call check_for_xor_used_as_pow.
>
> gcc/ChangeLog:
> PR c/90885
> * doc/invoke.texi (Warning Options): Add -Wxor-used-as-pow.
>
> gcc/testsuite/ChangeLog:
> PR c/90885
> * c-c++-common/Wxor-used-as-pow-1.c: New test.
> * c-c++-common/Wxor-used-as-pow-fixits.c: New test.
> * g++.dg/parse/expr3.C: Convert 2 to 0x2 to suppress
> -Wxor-used-as-pow.
> * g++.dg/warn/Wparentheses-10.C: Likewise.
> * g++.dg/warn/Wparentheses-18.C: Likewise.
> * g++.dg/warn/Wparentheses-19.C: Likewise.
> * g++.dg/warn/Wparentheses-9.C: Likewise.
> * g++.dg/warn/Wxor-used-as-pow-named-op.C: New test.
> * gcc.dg/Wparentheses-6.c: Convert 2 to 0x2 to suppress
> -Wxor-used-as-pow.
> * gcc.dg/Wparentheses-7.c: Likewise.
> * gcc.dg/precedence-1.c: Likewise.
>
> libcpp/ChangeLog:
> PR c/90885
> * include/cpplib.h (BOL): Move macro to 1 << 12 since it is
> not used by C/C++'s unsigned char token flags.
> (DECIMAL_INT): New, using 1 << 6, so that it is visible as
> part of C/C++'s 8 bits of token flags.
>
> Signed-off-by: David Malcolm <dmalcolm@redhat.com>
> ---
> gcc/c-family/c-common.h | 4 +
> gcc/c-family/c-lex.cc | 6 +-
> gcc/c-family/c-warn.cc | 94 +++++++++++++++++++
> gcc/c-family/c.opt | 4 +
> gcc/c/c-parser.cc | 9 ++
> gcc/c/c-tree.h | 3 +
> gcc/c/c-typeck.cc | 9 ++
> gcc/cp/cp-tree.h | 19 +++-
> gcc/cp/parser.cc | 17 +++-
> gcc/doc/invoke.texi | 15 +++
> .../c-c++-common/Wxor-used-as-pow-1.c | 57 +++++++++++
> .../c-c++-common/Wxor-used-as-pow-fixits.c | 34 +++++++
> gcc/testsuite/g++.dg/parse/expr3.C | 2 +-
> gcc/testsuite/g++.dg/warn/Wparentheses-10.C | 14 +--
> gcc/testsuite/g++.dg/warn/Wparentheses-18.C | 4 +-
> gcc/testsuite/g++.dg/warn/Wparentheses-19.C | 12 +--
> gcc/testsuite/g++.dg/warn/Wparentheses-9.C | 4 +-
> .../g++.dg/warn/Wxor-used-as-pow-named-op.C | 8 ++
> gcc/testsuite/gcc.dg/Wparentheses-6.c | 4 +-
> gcc/testsuite/gcc.dg/Wparentheses-7.c | 12 +--
> gcc/testsuite/gcc.dg/precedence-1.c | 4 +-
> libcpp/include/cpplib.h | 3 +-
> 22 files changed, 304 insertions(+), 34 deletions(-)
> create mode 100644 gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
> create mode 100644 gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
> create mode 100644 gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
>
> diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
> index c06769b6f0b..78ce94c6591 100644
> --- a/gcc/c-family/c-common.h
> +++ b/gcc/c-family/c-common.h
> @@ -1475,6 +1475,10 @@ extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
> extern void warn_for_multistatement_macros (location_t, location_t,
> location_t, enum rid);
>
> +extern void check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
> + location_t operator_loc,
> + tree rhs_val);
> +
> /* In c-attribs.cc. */
> extern bool attribute_takes_identifier_p (const_tree);
> extern tree handle_deprecated_attribute (tree *, tree, tree, int, bool *);
> diff --git a/gcc/c-family/c-lex.cc b/gcc/c-family/c-lex.cc
> index 8bfa4f4024f..1eda6f1fccc 100644
> --- a/gcc/c-family/c-lex.cc
> +++ b/gcc/c-family/c-lex.cc
> @@ -509,7 +509,11 @@ c_lex_with_flags (tree *value, location_t *loc, unsigned char *cpp_flags,
> /* C++ uses '0' to mark virtual functions as pure.
> Set PURE_ZERO to pass this information to the C++ parser. */
> if (tok->val.str.len == 1 && *tok->val.str.text == '0')
> - add_flags = PURE_ZERO;
> + add_flags = PURE_ZERO | DECIMAL_INT;
> + else if ((flags & CPP_N_INTEGER) && (flags & CPP_N_DECIMAL))
> + /* -Wxor-used-as-pow is only active for LHS of ^ expressed
> + as a decimal integer. */
> + add_flags = DECIMAL_INT;
> *value = interpret_integer (tok, flags, &overflow);
> break;
>
> diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
> index ea7335f3edf..ed79cc3ca40 100644
> --- a/gcc/c-family/c-warn.cc
> +++ b/gcc/c-family/c-warn.cc
> @@ -3799,3 +3799,97 @@ do_warn_array_compare (location_t location, tree_code code, tree op0, tree op1)
> op0, op_symbol_code (code), op1);
> }
> }
> +
> +/* Given LHS_VAL ^ RHS_VAL, where LHS_LOC is the location of the LHS and
> + OPERATOR_LOC is the location of the ^, complain with -Wxor-used-as-pow
> + if it looks like the user meant exponentiation rather than xor. */
> +
> +void
> +check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
> + location_t operator_loc,
> + tree rhs_val)
> +{
> + /* Only complain if both args are non-negative integer constants. */
> + if (!(TREE_CODE (lhs_val) == INTEGER_CST
> + && tree_int_cst_sgn (lhs_val) >= 0))
> + return;
> + if (!(TREE_CODE (rhs_val) == INTEGER_CST
> + && tree_int_cst_sgn (rhs_val) >= 0))
> + return;
> +
> + /* Only complain if the LHS is 2 or 10. */
> + unsigned HOST_WIDE_INT lhs_uhwi = tree_to_uhwi (lhs_val);
> + if (lhs_uhwi != 2 && lhs_uhwi != 10)
> + return;
> +
> + unsigned HOST_WIDE_INT rhs_uhwi = tree_to_uhwi (rhs_val);
> + unsigned HOST_WIDE_INT xor_result = lhs_uhwi ^ rhs_uhwi;
> + binary_op_rich_location loc (operator_loc,
> + lhs_val, rhs_val, false);
> +
> + /* If we issue fix-it hints with the warning then we will also issue a
> + note suggesting how to suppress the warning with a different change.
> + These proposed changes are incompatible. */
> + loc.fixits_cannot_be_auto_applied ();
> +
> + auto_diagnostic_group d;
> + bool warned = false;
> + if (lhs_uhwi == 2)
> + {
> + /* Would exponentiation fit in int, in long long, or not at all? */
> + if (rhs_uhwi < (INT_TYPE_SIZE - 1))
> + {
> + unsigned HOST_WIDE_INT suggested_result = 1 << rhs_uhwi;
> + loc.add_fixit_replace (lhs_loc, "1");
> + loc.add_fixit_replace (operator_loc, "<<");
> + warned = warning_at (&loc, OPT_Wxor_used_as_pow,
> + "result of %<%wu^%wu%> is %wu;"
> + " did you mean %<1 << %wu%> (%wu)?",
> + lhs_uhwi, rhs_uhwi, xor_result,
> + rhs_uhwi, suggested_result);
> + }
> + else if (rhs_uhwi < (LONG_LONG_TYPE_SIZE - 1))
> + {
> + loc.add_fixit_replace (lhs_loc, "1LL");
> + loc.add_fixit_replace (operator_loc, "<<");
> + warned = warning_at (&loc, OPT_Wxor_used_as_pow,
> + "result of %<%wu^%wu%> is %wu;"
> + " did you mean %<1LL << %wu%>?",
> + lhs_uhwi, rhs_uhwi, xor_result,
> + rhs_uhwi);
> + }
> + else if (rhs_uhwi <= LONG_LONG_TYPE_SIZE)
> + warned = warning_at (&loc, OPT_Wxor_used_as_pow,
> + "result of %<%wu^%wu%> is %wu;"
> + " did you mean exponentiation?",
> + lhs_uhwi, rhs_uhwi, xor_result);
> + /* Otherwise assume it's an xor. */
> + }
> + else
> + {
> + gcc_assert (lhs_uhwi == 10);
> + loc.add_fixit_replace (lhs_loc, "1");
> + loc.add_fixit_replace (operator_loc, "e");
> + warned = warning_at (&loc, OPT_Wxor_used_as_pow,
> + "result of %<%wu^%wu%> is %wu;"
> + " did you mean %<1e%wu%>?",
> + lhs_uhwi, rhs_uhwi, xor_result,
> + rhs_uhwi);
> + }
> + if (warned)
> + {
> + gcc_rich_location note_loc (lhs_loc);
> + if (lhs_uhwi == 2)
> + note_loc.add_fixit_replace (lhs_loc, "0x2");
> + else
> + {
> + gcc_assert (lhs_uhwi == 10);
> + note_loc.add_fixit_replace (lhs_loc, "0xa");
> + }
> + note_loc.fixits_cannot_be_auto_applied ();
> + inform (¬e_loc,
> + "you can silence this warning by using a hexadecimal constant"
> + " (%wx rather than %wd)",
> + lhs_uhwi, lhs_uhwi);
> + }
> +}
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index 44e1a60ce24..c11ea50ac42 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -1439,6 +1439,10 @@ Wwrite-strings
> C ObjC C++ ObjC++ Var(warn_write_strings) Warning
> In C++, nonzero means warn about deprecated conversion from string literals to 'char *'. In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
>
> +Wxor-used-as-pow
> +C C++ Common Var(warn_xor_used_as_pow) Warning Init(1)
> +Warn about xor operators where it appears the user meant exponentiation.
> +
> Wzero-as-null-pointer-constant
> C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
> Warn when a literal '0' is used as null pointer.
> diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
> index 92049d1a101..25064576829 100644
> --- a/gcc/c/c-parser.cc
> +++ b/gcc/c/c-parser.cc
> @@ -7496,6 +7496,7 @@ c_parser_string_literal (c_parser *parser, bool translate, bool wide_ok)
> ret.original_code = STRING_CST;
> ret.original_type = NULL_TREE;
> set_c_expr_source_range (&ret, get_range_from_loc (line_table, loc));
> + ret.m_decimal = 0;
> parser->seen_string_literal = true;
> return ret;
> }
> @@ -7575,6 +7576,7 @@ c_parser_expr_no_commas (c_parser *parser, struct c_expr *after,
> ret.value = build_modify_expr (op_location, lhs.value, lhs.original_type,
> code, exp_location, rhs.value,
> rhs.original_type);
> + ret.m_decimal = 0;
> set_c_expr_source_range (&ret, lhs.get_start (), rhs.get_finish ());
> if (code == NOP_EXPR)
> ret.original_code = MODIFY_EXPR;
> @@ -7712,6 +7714,7 @@ c_parser_conditional_expression (c_parser *parser, struct c_expr *after,
> : NULL);
> }
> set_c_expr_source_range (&ret, start, exp2.get_finish ());
> + ret.m_decimal = 0;
> return ret;
> }
>
> @@ -7901,6 +7904,7 @@ c_parser_binary_expression (c_parser *parser, struct c_expr *after,
> TREE_OPERAND (t, 0) = stack[0].expr.value; \
> TREE_OPERAND (t, 1) = stack[1].expr.value; \
> stack[0].expr.value = t; \
> + stack[0].expr.m_decimal = 0; \
> } \
> else \
> stack[sp - 1].expr = parser_build_binary_op (stack[sp].loc, \
> @@ -8187,6 +8191,7 @@ c_parser_unary_expression (c_parser *parser)
> ret.value = build_indirect_ref (combined_loc, op.value, RO_UNARY_STAR);
> ret.src_range.m_start = op_loc;
> ret.src_range.m_finish = finish;
> + ret.m_decimal = 0;
> return ret;
> }
> case CPP_PLUS:
> @@ -8560,6 +8565,7 @@ c_parser_has_attribute_expression (c_parser *parser)
> result.value = boolean_false_node;
>
> set_c_expr_source_range (&result, start, finish);
> + result.m_decimal = 0;
> return result;
> }
>
> @@ -8925,6 +8931,7 @@ c_parser_predefined_identifier (c_parser *parser)
> expr.value = fname_decl (loc, c_parser_peek_token (parser)->keyword,
> c_parser_peek_token (parser)->value);
> set_c_expr_source_range (&expr, loc, loc);
> + expr.m_decimal = 0;
> c_parser_consume_token (parser);
> return expr;
> }
> @@ -9003,12 +9010,14 @@ c_parser_postfix_expression (c_parser *parser)
> source_range tok_range = c_parser_peek_token (parser)->get_range ();
> expr.original_code = ERROR_MARK;
> expr.original_type = NULL;
> + expr.m_decimal = 0;
> switch (c_parser_peek_token (parser)->type)
> {
> case CPP_NUMBER:
> expr.value = c_parser_peek_token (parser)->value;
> set_c_expr_source_range (&expr, tok_range);
> loc = c_parser_peek_token (parser)->location;
> + expr.m_decimal = c_parser_peek_token (parser)->flags & DECIMAL_INT;
> c_parser_consume_token (parser);
> if (TREE_CODE (expr.value) == FIXED_CST
> && !targetm.fixed_point_supported_p ())
> diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
> index e655afd1cd4..b4231a17859 100644
> --- a/gcc/c/c-tree.h
> +++ b/gcc/c/c-tree.h
> @@ -147,6 +147,9 @@ struct c_expr
> etc), so we stash a copy here. */
> source_range src_range;
>
> + /* True if this was directly from a decimal constant token. */
> + bool m_decimal : 1;
> +
> /* Access to the first and last locations within the source spelling
> of this expression. */
> location_t get_start () const { return src_range.m_start; }
> diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
> index 8514488b7a5..1f5fa07c925 100644
> --- a/gcc/c/c-typeck.cc
> +++ b/gcc/c/c-typeck.cc
> @@ -3821,6 +3821,7 @@ parser_build_binary_op (location_t location, enum tree_code code,
> struct c_expr arg1, struct c_expr arg2)
> {
> struct c_expr result;
> + result.m_decimal = 0;
>
> enum tree_code code1 = arg1.original_code;
> enum tree_code code2 = arg2.original_code;
> @@ -3978,6 +3979,14 @@ parser_build_binary_op (location_t location, enum tree_code code,
> "comparison between %qT and %qT",
> type1, type2);
>
> + if (warn_xor_used_as_pow
> + && code == BIT_XOR_EXPR
> + && arg1.m_decimal
> + && arg2.m_decimal)
> + check_for_xor_used_as_pow (arg1.get_location (), arg1.value,
> + location,
> + arg2.value);
> +
> return result;
> }
> \f
> diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> index 3278b4114bd..cdff8282e64 100644
> --- a/gcc/cp/cp-tree.h
> +++ b/gcc/cp/cp-tree.h
> @@ -54,13 +54,23 @@ class cp_expr
> {
> public:
> cp_expr () :
> - m_value (NULL), m_loc (UNKNOWN_LOCATION) {}
> + m_value (NULL), m_loc (UNKNOWN_LOCATION),
> + m_decimal (false)
> + {}
>
> cp_expr (tree value) :
> - m_value (value), m_loc (cp_expr_location (m_value)) {}
> + m_value (value), m_loc (cp_expr_location (m_value)),
> + m_decimal (false)
> + {}
>
> cp_expr (tree value, location_t loc):
> - m_value (value), m_loc (loc)
> + m_value (value), m_loc (loc), m_decimal (false)
> + {
> + protected_set_expr_location (value, loc);
> + }
> +
> + cp_expr (tree value, location_t loc, bool decimal):
> + m_value (value), m_loc (loc), m_decimal (decimal)
> {
> protected_set_expr_location (value, loc);
> }
> @@ -102,9 +112,12 @@ public:
> return *this;
> }
>
> + bool decimal_p () const { return m_decimal; }
> +
> private:
> tree m_value;
> location_t m_loc;
> + bool m_decimal : 1;
> };
>
> inline bool
> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> index 33926d23179..73c46e79979 100644
> --- a/gcc/cp/parser.cc
> +++ b/gcc/cp/parser.cc
> @@ -2066,6 +2066,8 @@ struct cp_parser_expression_stack_entry
> enum cp_parser_prec prec;
> /* Location of the binary operation we are parsing. */
> location_t loc;
> + /* Flags from the operator token. */
> + unsigned char flags;
> };
>
> /* The stack for storing partial expressions. We only need NUM_PREC_VALUES
> @@ -5611,7 +5613,7 @@ cp_parser_primary_expression (cp_parser *parser,
> if (!cast_p)
> cp_parser_non_integral_constant_expression (parser, NIC_FLOAT);
> }
> - return (cp_expr (token->u.value, token->location)
> + return (cp_expr (token->u.value, token->location, token->flags & DECIMAL_INT)
> .maybe_add_location_wrapper ());
>
> case CPP_CHAR_USERDEF:
> @@ -10157,6 +10159,7 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
> get_rhs:
> current.tree_type = binops_by_token[token->type].tree_type;
> current.loc = token->location;
> + current.flags = token->flags;
>
> /* We used the operator token. */
> cp_lexer_consume_token (parser->lexer);
> @@ -10241,6 +10244,18 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
> warn_logical_not_parentheses (current.loc, current.tree_type,
> current.lhs, maybe_constant_value (rhs));
>
> + if (warn_xor_used_as_pow
> + && current.tree_type == BIT_XOR_EXPR
> + /* Don't warn for named "xor" (as opposed to '^'). */
> + && !(current.flags & NAMED_OP)
> + && current.lhs.decimal_p ()
> + && rhs.decimal_p ())
> + check_for_xor_used_as_pow
> + (current.lhs.get_location (),
> + tree_strip_any_location_wrapper (current.lhs),
> + current.loc,
> + tree_strip_any_location_wrapper (rhs));
> +
> overload = NULL;
>
> location_t combined_loc = make_location (current.loc,
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index a17c059d515..31516ded123 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -414,6 +414,7 @@ Objective-C and Objective-C++ Dialects}.
> -Wvector-operation-performance @gol
> -Wvla -Wvla-larger-than=@var{byte-size} -Wno-vla-larger-than @gol
> -Wvolatile-register-var -Wwrite-strings @gol
> +-Wxor-used-as-pow @gol
> -Wzero-length-bounds}
>
> @item Static Analyzer Options
> @@ -9661,6 +9662,20 @@ modifier does not inhibit all optimizations that may eliminate reads
> and/or writes to register variables. This warning is enabled by
> @option{-Wall}.
>
> +@item -Wxor-used-as-pow @r{(C, C++, Objective-C and Objective-C++ only)}
> +@opindex Wxor-used-as-pow
> +@opindex Wno-xor-used-as-pow
> +Warn about uses of @code{^}, the exclusive or operator, where it appears
> +the user meant exponentiation. Specifically, the warning occurs when the
> +left-hand side is the decimal constant 2 or 10 and the right-hand side
> +is also a decimal constant.
> +
> +In C and C++, @code{^} means exclusive or, whereas in some other languages
> +(e.g. TeX and some versions of BASIC) it means exponentiation.
> +
> +This warning is enabled by default. It can be silenced by converting one
> +of the operands to hexadecimal.
> +
> @item -Wdisabled-optimization
> @opindex Wdisabled-optimization
> @opindex Wno-disabled-optimization
> diff --git a/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
> new file mode 100644
> index 00000000000..962902c3a05
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-1.c
> @@ -0,0 +1,57 @@
> +/* The precise output depends of sizeof(int) and sizeof(long long), so
> + filter by target. */
> +/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
> +
> +/* Apparent uses of ^ for powers of 2. */
> +
> +short t2_16 = 2^16; /* { dg-warning "result of '2\\^16' is 18; did you mean '1 << 16' \\(65536\\)\\? \\\[-Wxor-used-as-pow\\\]" } */
> +int t2_17 = 2^17; /* { dg-warning "result of '2\\^17' is 19; did you mean '1 << 17' \\(131072\\)\\?" } */
> +int t2_30 = 2^30; /* { dg-warning "result of '2\\^30' is 28; did you mean '1 << 30' \\(1073741824\\)\\?" } */
> +
> +/* Should be 1LL at 31 and above, due to overflow. */
> +int t2_31 = 2^31; /* { dg-warning "result of '2\\^31' is 29; did you mean '1LL << 31'\\?" } */
> +int t2_32 = 2^32; /* { dg-warning "result of '2\\^32' is 34; did you mean '1LL << 32'\\?" } */
> +
> +long t2_63 = 2^63; /* { dg-warning "result of '2\\^63' is 61; did you mean exponentiation\\?" } */
> +long t2_64 = 2^64; /* { dg-warning "result of '2\\^64' is 66; did you mean exponentiation\\?" } */
> +
> +/* ...but don't warn when RHS is large enough. */
> +long t2_65 = 2^65;
> +long t2_127 = 2^127;
> +long t2_128 = 2^128;
> +long t2_129 = 2^129;
> +
> +/* Verify that -Wxor-used-as-pow happens before folding. */
> +long t2_32_m1 = ((2^32)-1); /* { dg-warning "result of '2\\^32' is 34; did you mean '1LL << 32'\\?" } */
> +
> +
> +/* Apparent uses of ^ for powers of 10. */
> +
> +long t10_2 = 10^2; /* { dg-warning "result of '10\\^2' is 8; did you mean '1e2'\\?" } */
> +long t10_9 = 10^9; /* { dg-warning "result of '10\\^9' is 3; did you mean '1e9'\\?" } */
> +long t10_10 = 10^10; /* { dg-warning "result of '10\\^10' is 0; did you mean '1e10'\\?" } */
> +long t10_100 = 10^100; /* { dg-warning "result of '10\\^100' is 110; did you mean '1e100'\\?" } */
> +
> +/* Don't warn on negatives. */
> +long tm2_2 = -2^2;
> +long t2_m2 = 2^-2;
> +long tm10_10 = -10^10;
> +long t10_m10 = 10^-10;
> +
> +/* If LHS is not 2 or 10, we shouldn't complain. */
> +int t0_0 = 0 ^ 0;
> +int t6_7 = 6 ^ 7;
> +
> +/* Floating point is already covered by type-checking. */
> +float f10_10 = 10.f^10; /* { dg-error "invalid operands to binary \\^ \\(have 'float' and 'int'\\)" "" { target c } } */
> +/* { dg-error "invalid operands of types 'float' and 'int' to binary 'operator\\^'" "" { target c++ } .-1 } */
> +
> +/* Don't complain if the LHS isn't literal decimal 2 or 10. */
> +int t1p1_16 = (1 + 1) ^ 16;
> +int t5p5_6 = (5 + 5) ^ 6;
> +int h2_8 = 0x2 ^ 8;
> +int h10_3 = 0xa ^ 3;
> +
> +/* Don't complain if the RHS isn't literal decimal. */
> +int t2_x16 = 2^0x10;
> +int h10_x3 = 10 ^ 0x3;
> diff --git a/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
> new file mode 100644
> index 00000000000..f612b761c30
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/Wxor-used-as-pow-fixits.c
> @@ -0,0 +1,34 @@
> +/* { dg-options "-fdiagnostics-show-caret" } */
> +
> +/* Test fixit hints for -Wxor-used-as-pow. */
> +
> +int t2_8 = 2^8; /* { dg-line line_a } */
> +/* { dg-warning "result of '2\\^8' is 10; did you mean '1 << 8' \\(256\\)\\?" "warn" { target *-*-* } line_a } */
> +/* { dg-begin-multiline-output "" }
> + int t2_8 = 2^8;
> + ^
> + --
> + 1<<
> + { dg-end-multiline-output "" } */
> +/* { dg-message "you can silence this warning by using a hexadecimal constant \\(0x2 rather than 2\\)" "note" { target *-*-* } line_a } */
> +/* { dg-begin-multiline-output "" }
> + int t2_8 = 2^8;
> + ^
> + 0x2
> + { dg-end-multiline-output "" } */
> +
> +
> +int t10_6 = 10^6; /* { dg-line line_b } */
> +/* { dg-warning "result of '10\\^6' is 12; did you mean '1e6'\\?" "warn" { target *-*-* } line_b } */
> +/* { dg-begin-multiline-output "" }
> + int t10_6 = 10^6;
> + ^
> + ---
> + 1e
> + { dg-end-multiline-output "" } */
> +/* { dg-message "you can silence this warning by using a hexadecimal constant \\(0xa rather than 10\\)" "note" { target *-*-* } line_b } */
> +/* { dg-begin-multiline-output "" }
> + int t10_6 = 10^6;
> + ^~
> + 0xa
> + { dg-end-multiline-output "" } */
> diff --git a/gcc/testsuite/g++.dg/parse/expr3.C b/gcc/testsuite/g++.dg/parse/expr3.C
> index 95d332f41b0..1e166733843 100644
> --- a/gcc/testsuite/g++.dg/parse/expr3.C
> +++ b/gcc/testsuite/g++.dg/parse/expr3.C
> @@ -23,7 +23,7 @@
>
> test (||, &&, 1, 1, 0, 0)
> test (&&, |, 5, 1, 1, 19)
> -test (|, ^, 1, 2, 2, 1)
> +test (|, ^, 1, 2, 0x2, 1)
> test (^, &, 1, 3, 2, 6)
> test (&, ==, 1, 3, 2, 0)
> test (==, <, 2, 0, 0, 0)
> diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-10.C b/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
> index 557db091ad0..a5d28efcc2e 100644
> --- a/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
> +++ b/gcc/testsuite/g++.dg/warn/Wparentheses-10.C
> @@ -16,7 +16,7 @@ bar (int a, int b, int c)
> foo (1 & (2 ^ c));
> foo (1 & 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 & 2) ^ 3);
> - foo (1 & (2 ^ 3));
> + foo (1 & (0x2 ^ 3));
> foo (a ^ b & c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) & c);
> foo (a ^ (b & c));
> @@ -34,7 +34,7 @@ bar (int a, int b, int c)
> foo (1 + (2 ^ c));
> foo (1 + 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 + 2) ^ 3);
> - foo (1 + (2 ^ 3));
> + foo (1 + (0x2 ^ 3));
> foo (a ^ b + c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) + c);
> foo (a ^ (b + c));
> @@ -52,7 +52,7 @@ bar (int a, int b, int c)
> foo (1 - (2 ^ c));
> foo (1 - 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 - 2) ^ 3);
> - foo (1 - (2 ^ 3));
> + foo (1 - (0x2 ^ 3));
> foo (a ^ b - c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) - c);
> foo (a ^ (b - c));
> @@ -70,7 +70,7 @@ bar (int a, int b, int c)
> foo (1 >= (2 ^ c));
> foo (1 >= 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 >= 2) ^ 3);
> - foo (1 >= (2 ^ 3));
> + foo (1 >= (0x2 ^ 3));
> foo (a ^ b >= c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) >= c);
> foo (a ^ (b >= c));
> @@ -88,7 +88,7 @@ bar (int a, int b, int c)
> foo (1 == (2 ^ c));
> foo (1 == 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 == 2) ^ 3);
> - foo (1 == (2 ^ 3));
> + foo (1 == (0x2 ^ 3));
> foo (a ^ b == c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) == c);
> foo (a ^ (b == c));
> @@ -104,9 +104,9 @@ bar (int a, int b, int c)
> foo (1 < 2 ^ c); // { dg-warning "parentheses" "correct warning" }
> foo ((1 < 2) ^ c);
> foo (1 < (2 ^ c));
> - foo (1 < 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> + foo (1 < 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 < 2) ^ 3);
> - foo (1 < (2 ^ 3));
> + foo (1 < (0x2 ^ 3));
> foo (a ^ b < c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) < c);
> foo (a ^ (b < c));
> diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-18.C b/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
> index 83efaff4189..d50fad8ae80 100644
> --- a/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
> +++ b/gcc/testsuite/g++.dg/warn/Wparentheses-18.C
> @@ -42,9 +42,9 @@ bar (T a, T b, T c)
> foo (1 | 2 ^ c); // { dg-warning "parentheses" "correct warning" }
> foo ((1 | 2) ^ c);
> foo (1 | (2 ^ c));
> - foo (1 | 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> + foo (1 | 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 | 2) ^ 3);
> - foo (1 | (2 ^ 3));
> + foo (1 | (0x2 ^ 3));
> foo (a + b | c); // { dg-warning "parentheses" "correct warning" }
> foo ((a + b) | c);
> foo (a + (b | c));
> diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-19.C b/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
> index f0e2b805c9e..2ad8036ac84 100644
> --- a/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
> +++ b/gcc/testsuite/g++.dg/warn/Wparentheses-19.C
> @@ -17,7 +17,7 @@ bar (T a, T b, T c)
> foo (1 & (2 ^ c));
> foo (1 & 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 & 2) ^ 3);
> - foo (1 & (2 ^ 3));
> + foo (1 & (0x2 ^ 3));
> foo (a ^ b & c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) & c);
> foo (a ^ (b & c));
> @@ -35,7 +35,7 @@ bar (T a, T b, T c)
> foo (1 + (2 ^ c));
> foo (1 + 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 + 2) ^ 3);
> - foo (1 + (2 ^ 3));
> + foo (1 + (0x2 ^ 3));
> foo (a ^ b + c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) + c);
> foo (a ^ (b + c));
> @@ -53,7 +53,7 @@ bar (T a, T b, T c)
> foo (1 - (2 ^ c));
> foo (1 - 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 - 2) ^ 3);
> - foo (1 - (2 ^ 3));
> + foo (1 - (0x2 ^ 3));
> foo (a ^ b - c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) - c);
> foo (a ^ (b - c));
> @@ -71,7 +71,7 @@ bar (T a, T b, T c)
> foo (1 >= (2 ^ c));
> foo (1 >= 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 >= 2) ^ 3);
> - foo (1 >= (2 ^ 3));
> + foo (1 >= (0x2 ^ 3));
> foo (a ^ b >= c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) >= c);
> foo (a ^ (b >= c));
> @@ -89,7 +89,7 @@ bar (T a, T b, T c)
> foo (1 == (2 ^ c));
> foo (1 == 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 == 2) ^ 3);
> - foo (1 == (2 ^ 3));
> + foo (1 == (0x2 ^ 3));
> foo (a ^ b == c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) == c);
> foo (a ^ (b == c));
> @@ -107,7 +107,7 @@ bar (T a, T b, T c)
> foo (1 < (2 ^ c));
> foo (1 < 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 < 2) ^ 3);
> - foo (1 < (2 ^ 3));
> + foo (1 < (0x2 ^ 3));
> foo (a ^ b < c); // { dg-warning "parentheses" "correct warning" }
> foo ((a ^ b) < c);
> foo (a ^ (b < c));
> diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-9.C b/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
> index 7c8f01d327b..69976b3bacf 100644
> --- a/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
> +++ b/gcc/testsuite/g++.dg/warn/Wparentheses-9.C
> @@ -41,9 +41,9 @@ bar (int a, int b, int c)
> foo (1 | 2 ^ c); // { dg-warning "parentheses" "correct warning" }
> foo ((1 | 2) ^ c);
> foo (1 | (2 ^ c));
> - foo (1 | 2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> + foo (1 | 0x2 ^ 3); // { dg-warning "parentheses" "correct warning" }
> foo ((1 | 2) ^ 3);
> - foo (1 | (2 ^ 3));
> + foo (1 | (0x2 ^ 3));
> foo (a + b | c); // { dg-warning "parentheses" "correct warning" }
> foo ((a + b) | c);
> foo (a + (b | c));
> diff --git a/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C b/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
> new file mode 100644
> index 00000000000..4899d72b11b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wxor-used-as-pow-named-op.C
> @@ -0,0 +1,8 @@
> +/* Verify that -Wxor-used-as-pow only warns with ^ and not with
> + named "xor". */
> +
> +int t2_16 = 2^16; /* { dg-warning "result of '2\\^16' is 18; did you mean '1 << 16' \\(65536\\)\\?" } */
> +int t2x16 = 2 xor 16;
> +
> +int t10_6 = 10^6; /* { dg-warning "result of '10\\^6' is 12; did you mean '1e6'\\?" } */
> +int t10x6 = 10 xor 6;
> diff --git a/gcc/testsuite/gcc.dg/Wparentheses-6.c b/gcc/testsuite/gcc.dg/Wparentheses-6.c
> index 2d2cc161394..260b6adebea 100644
> --- a/gcc/testsuite/gcc.dg/Wparentheses-6.c
> +++ b/gcc/testsuite/gcc.dg/Wparentheses-6.c
> @@ -43,9 +43,9 @@ bar (int a, int b, int c)
> foo (1 | 2 ^ c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 | 2) ^ c);
> foo (1 | (2 ^ c));
> - foo (1 | 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> + foo (1 | 0x2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 | 2) ^ 3);
> - foo (1 | (2 ^ 3));
> + foo (1 | (0x2 ^ 3));
> foo (a + b | c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a + b) | c);
> foo (a + (b | c));
> diff --git a/gcc/testsuite/gcc.dg/Wparentheses-7.c b/gcc/testsuite/gcc.dg/Wparentheses-7.c
> index f3516969d23..6805094d296 100644
> --- a/gcc/testsuite/gcc.dg/Wparentheses-7.c
> +++ b/gcc/testsuite/gcc.dg/Wparentheses-7.c
> @@ -18,7 +18,7 @@ bar (int a, int b, int c)
> foo (1 & (2 ^ c));
> foo (1 & 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 & 2) ^ 3);
> - foo (1 & (2 ^ 3));
> + foo (1 & (0x2 ^ 3));
> foo (a ^ b & c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) & c);
> foo (a ^ (b & c));
> @@ -36,7 +36,7 @@ bar (int a, int b, int c)
> foo (1 + (2 ^ c));
> foo (1 + 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 + 2) ^ 3);
> - foo (1 + (2 ^ 3));
> + foo (1 + (0x2 ^ 3));
> foo (a ^ b + c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) + c);
> foo (a ^ (b + c));
> @@ -54,7 +54,7 @@ bar (int a, int b, int c)
> foo (1 - (2 ^ c));
> foo (1 - 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 - 2) ^ 3);
> - foo (1 - (2 ^ 3));
> + foo (1 - (0x2 ^ 3));
> foo (a ^ b - c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) - c);
> foo (a ^ (b - c));
> @@ -72,7 +72,7 @@ bar (int a, int b, int c)
> foo (1 >= (2 ^ c));
> foo (1 >= 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 >= 2) ^ 3);
> - foo (1 >= (2 ^ 3));
> + foo (1 >= (0x2 ^ 3));
> foo (a ^ b >= c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) >= c);
> foo (a ^ (b >= c));
> @@ -90,7 +90,7 @@ bar (int a, int b, int c)
> foo (1 == (2 ^ c));
> foo (1 == 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 == 2) ^ 3);
> - foo (1 == (2 ^ 3));
> + foo (1 == (0x2 ^ 3));
> foo (a ^ b == c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) == c);
> foo (a ^ (b == c));
> @@ -108,7 +108,7 @@ bar (int a, int b, int c)
> foo (1 < (2 ^ c));
> foo (1 < 2 ^ 3); /* { dg-warning "parentheses" "correct warning" } */
> foo ((1 < 2) ^ 3);
> - foo (1 < (2 ^ 3));
> + foo (1 < (0x2 ^ 3));
> foo (a ^ b < c); /* { dg-warning "parentheses" "correct warning" } */
> foo ((a ^ b) < c);
> foo (a ^ (b < c));
> diff --git a/gcc/testsuite/gcc.dg/precedence-1.c b/gcc/testsuite/gcc.dg/precedence-1.c
> index f3f1e352708..089cdfc1472 100644
> --- a/gcc/testsuite/gcc.dg/precedence-1.c
> +++ b/gcc/testsuite/gcc.dg/precedence-1.c
> @@ -135,10 +135,10 @@ f (void)
> ASSERT_BIN (0, !=, 2, &, 1, 1, 1, 0);
> ASSERT_BIN (1, &, 2, ==, 0, 0, 1, 0);
> ASSERT_BIN (1, &, 2, !=, 0, 1, 0, 1);
> - ASSERT_BIN (1, &, 2, ^, 3, 3, 3, 1);
> + ASSERT_BIN (1, &, 0x2, ^, 3, 3, 3, 1);
> ASSERT_BIN (3, ^, 2, &, 1, 3, 1, 3);
> ASSERT_BIN (3, ^, 2, |, 1, 1, 1, 0);
> - ASSERT_BIN (3, |, 2, ^, 1, 3, 2, 3);
> + ASSERT_BIN (3, |, 0x2, ^, 1, 3, 2, 3);
> ASSERT_BIN (2, |, 0, &&, 2, 1, 1, 2);
> ASSERT_BIN (2, &&, 0, |, 2, 1, 2, 1);
> ASSERT_BIN (0, &&, 0, ||, 1, 1, 1, 0);
> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> index 3eba6f74b57..f1e7c2b3b2a 100644
> --- a/libcpp/include/cpplib.h
> +++ b/libcpp/include/cpplib.h
> @@ -190,7 +190,7 @@ struct GTY(()) cpp_string {
> #define NAMED_OP (1 << 4) /* C++ named operators. */
> #define PREV_FALLTHROUGH (1 << 5) /* On a token preceeded by FALLTHROUGH
> comment. */
> -#define BOL (1 << 6) /* Token at beginning of line. */
> +#define DECIMAL_INT (1 << 6) /* Decimal integer, set in c-lex.cc. */
> #define PURE_ZERO (1 << 7) /* Single 0 digit, used by the C++ frontend,
> set in c-lex.cc. */
> #define SP_DIGRAPH (1 << 8) /* # or ## token was a digraph. */
> @@ -199,6 +199,7 @@ struct GTY(()) cpp_string {
> after a # operator. */
> #define NO_EXPAND (1 << 10) /* Do not macro-expand this token. */
> #define PRAGMA_OP (1 << 11) /* _Pragma token. */
> +#define BOL (1 << 12) /* Token at beginning of line. */
>
> /* Specify which field, if any, of the cpp_token union is used. */
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885]
2022-08-12 1:38 [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885] David Malcolm
2022-08-30 20:18 ` Jason Merrill
@ 2022-08-30 20:40 ` Marek Polacek
2022-09-02 22:39 ` David Malcolm
1 sibling, 1 reply; 4+ messages in thread
From: Marek Polacek @ 2022-08-30 20:40 UTC (permalink / raw)
To: David Malcolm; +Cc: gcc-patches
This looks good to me, one thing though:
On Thu, Aug 11, 2022 at 09:38:12PM -0400, David Malcolm via Gcc-patches wrote:
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -1439,6 +1439,10 @@ Wwrite-strings
> C ObjC C++ ObjC++ Var(warn_write_strings) Warning
> In C++, nonzero means warn about deprecated conversion from string literals to 'char *'. In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
>
> +Wxor-used-as-pow
> +C C++ Common Var(warn_xor_used_as_pow) Warning Init(1)
This doesn't include ObjC/ObjC++, but...
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -414,6 +414,7 @@ Objective-C and Objective-C++ Dialects}.
> -Wvector-operation-performance @gol
> -Wvla -Wvla-larger-than=@var{byte-size} -Wno-vla-larger-than @gol
> -Wvolatile-register-var -Wwrite-strings @gol
> +-Wxor-used-as-pow @gol
> -Wzero-length-bounds}
>
> @item Static Analyzer Options
> @@ -9661,6 +9662,20 @@ modifier does not inhibit all optimizations that may eliminate reads
> and/or writes to register variables. This warning is enabled by
> @option{-Wall}.
>
> +@item -Wxor-used-as-pow @r{(C, C++, Objective-C and Objective-C++ only)}
...here it includes Objective-C and Objective-C++.
Marek
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885]
2022-08-30 20:40 ` Marek Polacek
@ 2022-09-02 22:39 ` David Malcolm
0 siblings, 0 replies; 4+ messages in thread
From: David Malcolm @ 2022-09-02 22:39 UTC (permalink / raw)
To: Marek Polacek; +Cc: gcc-patches
On Tue, 2022-08-30 at 16:40 -0400, Marek Polacek wrote:
> This looks good to me, one thing though:
>
> On Thu, Aug 11, 2022 at 09:38:12PM -0400, David Malcolm via Gcc-
> patches wrote:
> > --- a/gcc/c-family/c.opt
> > +++ b/gcc/c-family/c.opt
> > @@ -1439,6 +1439,10 @@ Wwrite-strings
> > C ObjC C++ ObjC++ Var(warn_write_strings) Warning
> > In C++, nonzero means warn about deprecated conversion from string
> > literals to 'char *'. In C, similar warning, except that the
> > conversion is of course not deprecated by the ISO C standard.
> >
> > +Wxor-used-as-pow
> > +C C++ Common Var(warn_xor_used_as_pow) Warning Init(1)
>
> This doesn't include ObjC/ObjC++, but...
I added ObjC/ObjC++ (and dropped Common), and retested it (and tested
it with -xobjective-c and -xobjective-c++); I've pushed it to trunk as
r13-2386-gbedfca647a9e9c.
Thanks
Dave
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-09-02 22:39 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-08-12 1:38 [PATCH] c/c++: new warning: -Wxor-used-as-pow [PR90885] David Malcolm
2022-08-30 20:18 ` Jason Merrill
2022-08-30 20:40 ` Marek Polacek
2022-09-02 22:39 ` David Malcolm
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).