From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1734) id AF4273858D1E; Wed, 4 May 2022 20:13:41 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AF4273858D1E MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Marek Polacek To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-122] c-family: Tweak -Woverflow diagnostic X-Act-Checkin: gcc X-Git-Author: Marek Polacek X-Git-Refname: refs/heads/trunk X-Git-Oldrev: a733dea9e7c39352ce9f72059938833eaa819467 X-Git-Newrev: 1cd3faf5dddb3cbfa2ed308ecf3db4f70bff337e Message-Id: <20220504201341.AF4273858D1E@sourceware.org> Date: Wed, 4 May 2022 20:13:41 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 May 2022 20:13:41 -0000 https://gcc.gnu.org/g:1cd3faf5dddb3cbfa2ed308ecf3db4f70bff337e commit r13-122-g1cd3faf5dddb3cbfa2ed308ecf3db4f70bff337e Author: Marek Polacek Date: Wed Mar 30 16:59:33 2022 -0400 c-family: Tweak -Woverflow diagnostic When g++ emits warning: overflow in conversion from 'int' to 'char' changes value from '300' to '','' for code like "char c = 300;" it might raise a few eyebrows. With this warning we're not interested in the ASCII representation of the char, only the numerical value, so convert constants of type char to int. It looks like this conversion only needs to be done for char_type_node. gcc/c-family/ChangeLog: * c-warn.cc (warnings_for_convert_and_check): Convert constants of type char to int. gcc/testsuite/ChangeLog: * c-c++-common/Wconversion-1.c: New test. Diff: --- gcc/c-family/c-warn.cc | 16 +++++++++++----- gcc/testsuite/c-c++-common/Wconversion-1.c | 14 ++++++++++++++ 2 files changed, 25 insertions(+), 5 deletions(-) diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc index f24ac5d0539..cae89294aea 100644 --- a/gcc/c-family/c-warn.cc +++ b/gcc/c-family/c-warn.cc @@ -1404,8 +1404,14 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr, result = TREE_OPERAND (result, 1); bool cst = TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant; - tree exprtype = TREE_TYPE (expr); + tree result_diag; + /* We're interested in the actual numerical value here, not its ASCII + representation. */ + if (cst && TYPE_MAIN_VARIANT (TREE_TYPE (result)) == char_type_node) + result_diag = fold_convert (integer_type_node, result); + else + result_diag = result; if (TREE_CODE (expr) == INTEGER_CST && (TREE_CODE (type) == INTEGER_TYPE @@ -1430,7 +1436,7 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr, "changes value from %qE to %qE") : G_("unsigned conversion from %qT to %qT " "changes value from %qE to %qE")), - exprtype, type, expr, result); + exprtype, type, expr, result_diag); else warning_at (loc, OPT_Woverflow, (TYPE_UNSIGNED (exprtype) @@ -1449,7 +1455,7 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr, warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " "changes value from %qE to %qE", - exprtype, type, expr, result); + exprtype, type, expr, result_diag); else warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " @@ -1466,7 +1472,7 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr, warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " "changes value from %qE to %qE", - exprtype, type, expr, result); + exprtype, type, expr, result_diag); else warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " @@ -1483,7 +1489,7 @@ warnings_for_convert_and_check (location_t loc, tree type, tree expr, warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " "changes value from %qE to %qE", - exprtype, type, expr, result); + exprtype, type, expr, result_diag); else warning_at (loc, OPT_Woverflow, "overflow in conversion from %qT to %qT " diff --git a/gcc/testsuite/c-c++-common/Wconversion-1.c b/gcc/testsuite/c-c++-common/Wconversion-1.c new file mode 100644 index 00000000000..ed65918c70f --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wconversion-1.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-Wconversion" } */ + +typedef char T; + +void g() +{ + char c = 300; /* { dg-warning "conversion from .int. to .char. changes value from .300. to .44." } */ + T t = 300; /* { dg-warning "conversion from .int. to .T. {aka .char.} changes value from .300. to .44." } */ + signed char sc = 300; /* { dg-warning "conversion from .int. to .signed char. changes value from .300. to .44." } */ + unsigned char uc = 300; /* { dg-warning "conversion from .int. to .unsigned char. changes value from .300. to .44." } */ + unsigned char uc2 = 300u; /* { dg-warning "conversion from .unsigned int. to .unsigned char. changes value from .300. to .44." } */ + char c2 = (double)1.0 + 200; /* { dg-warning "overflow in conversion from .double. to .char. changes value from .2.01e\\+2. to .127." } */ +}