From 505ce5abd48385f1b415b6ed0aed80e5b378249c Mon Sep 17 00:00:00 2001 From: David Malcolm Date: Fri, 17 Aug 2018 21:56:21 +0000 Subject: [PATCH] C++: -Wwrite-strings: use location of string constant Consider: extern int callee (const char *one, char *two, const char *three); int test () { return callee ("first", "second", "third"); } for which -Wwrite-strings was emitting: Wwrite-strings.C: In function 'int test()': Wwrite-strings.C:10:44: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings] 10 | return callee ("first", "second", "third"); | ^ This patch fixes the warning so that it underlines the pertinent argument at the callsite: Wwrite-strings.C: In function 'int test()': Wwrite-strings.C:10:27: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings] 10 | return callee ("first", "second", "third"); | ^~~~~~~~ Ideally we ought to also issue a "note" highlighting the pertinent parameter within the decl, but that's not readily available, so I'm saving it for another patch. gcc/cp/ChangeLog: * typeck.c (string_conv_p): Extract location from EXP and use it in preference to input_location when issuing warnings. gcc/testsuite/ChangeLog: * g++.dg/conversion/Wwrite-strings.C: New test. From-SVN: r263635 --- gcc/cp/ChangeLog | 5 ++++ gcc/cp/typeck.c | 10 ++++---- gcc/testsuite/ChangeLog | 4 ++++ .../g++.dg/conversion/Wwrite-strings.C | 24 +++++++++++++++++++ 4 files changed, 39 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/conversion/Wwrite-strings.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 0b695907cf1..d8be93089b4 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,8 @@ +2018-08-17 David Malcolm + + * typeck.c (string_conv_p): Extract location from EXP and use it + in preference to input_location when issuing warnings. + 2018-08-15 David Malcolm * call.c: Include "gcc-rich-location.h". diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index 64b3d583356..8c13ae9b19b 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -2208,6 +2208,8 @@ string_conv_p (const_tree totype, const_tree exp, int warn) && !same_type_p (t, wchar_type_node)) return 0; + location_t loc = EXPR_LOC_OR_LOC (exp, input_location); + STRIP_ANY_LOCATION_WRAPPER (exp); if (TREE_CODE (exp) == STRING_CST) @@ -2230,13 +2232,13 @@ string_conv_p (const_tree totype, const_tree exp, int warn) if (warn) { if (cxx_dialect >= cxx11) - pedwarn (input_location, OPT_Wwrite_strings, + pedwarn (loc, OPT_Wwrite_strings, "ISO C++ forbids converting a string constant to %qT", totype); else - warning (OPT_Wwrite_strings, - "deprecated conversion from string constant to %qT", - totype); + warning_at (loc, OPT_Wwrite_strings, + "deprecated conversion from string constant to %qT", + totype); } return 1; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index ea1f1fa6061..b8677d729bc 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2018-08-17 David Malcolm + + * g++.dg/conversion/Wwrite-strings.C: New test. + 2018-08-17 Sandra Loosemore Chung-Lin Tang Xianmiao Qu diff --git a/gcc/testsuite/g++.dg/conversion/Wwrite-strings.C b/gcc/testsuite/g++.dg/conversion/Wwrite-strings.C new file mode 100644 index 00000000000..f6dbb150699 --- /dev/null +++ b/gcc/testsuite/g++.dg/conversion/Wwrite-strings.C @@ -0,0 +1,24 @@ +// { dg-options "-fdiagnostics-show-caret" } + +/* Verify that -Wwrite-strings underlines the string literal in question. */ + +extern int callee (const char *one, char *two, const char *three); + +int test_1 () +{ + return callee ("first", "second", "third"); // { dg-warning "string constant to 'char\\*'" } + /* { dg-begin-multiline-output "" } + return callee ("first", "second", "third"); + ^~~~~~~~ + { dg-end-multiline-output "" } */ + // TODO: underline the pertinent param in the decl of callee +} + +char *test_2 (void) +{ + return "foo"; // { dg-warning "string constant to 'char\\*'" } + /* { dg-begin-multiline-output "" } + return "foo"; + ^~~~~ + { dg-end-multiline-output "" } */ +} -- 2.30.2