[committed]: C++: -Wwrite-strings: use location of string constant
David Malcolm
dmalcolm@redhat.com
Fri Aug 17 21:57:00 GMT 2018
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.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Committed to trunk as r263635.
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.
---
gcc/cp/typeck.c | 10 ++++++----
gcc/testsuite/g++.dg/conversion/Wwrite-strings.C | 24 ++++++++++++++++++++++++
2 files changed, 30 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/conversion/Wwrite-strings.C
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 64b3d58..8c13ae9 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/g++.dg/conversion/Wwrite-strings.C b/gcc/testsuite/g++.dg/conversion/Wwrite-strings.C
new file mode 100644
index 0000000..f6dbb15
--- /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 "" } */
+}
--
1.8.5.3
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