libstdc++: Add nonnull to starts_with/ends_with/contains string members

Ideally this wouldn't be needed, because eventually these pointers all
get passed to either the basic_string_view(const CharT*) constructor, or
to basic_string_view::find(const CharT*), both of which already have the
attribute. But for that to work requires optimization, so that the null
value gets propagated through the call chain.

Adding it explicitly to each member that requires a non-null pointer
makes the diagnostics more reliable even without optimization. It's
better to give a diagnostic earlier anyway, at the actual problematic
call in the user's code.

libstdc++-v3/ChangeLog:

	* include/bits/basic_string.h (starts_with, ends_with, contains):
	Add nonnull attribute.
	* include/bits/cow_string.h (starts_with, ends_with, contains):
	Likewise.
	* include/std/string_view (starts_with, ends_with, contains):
	Likewise.
	* testsuite/21_strings/basic_string/operations/contains/nonnull.cc
	* testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
	* testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
	* testsuite/21_strings/basic_string_view/operations/contains/nonnull.cc
	* testsuite/21_strings/basic_string_view/operations/ends_with/nonnull.cc
	* testsuite/21_strings/basic_string_view/operations/starts_with/nonnull.cc

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index b04fba956783fdcea83deaab763b6744787583c5..9d8b415302b2fa39e9056a68064296e3103d2a36 100644 (file)
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -3400,6 +3400,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       starts_with(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).starts_with(__x); }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       starts_with(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).starts_with(__x); }
@@ -3412,6 +3413,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       ends_with(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       ends_with(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
@@ -3426,6 +3428,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       contains(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).contains(__x); }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       contains(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).contains(__x); }

diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h
index f16e33ac1ef8c53ff3c55f7be9a941b401986b7b..f5f03338eec272f903d9ad2709a5d491fe4a3511 100644 (file)
--- a/libstdc++-v3/include/bits/cow_string.h
+++ b/libstdc++-v3/include/bits/cow_string.h
@@ -3012,6 +3012,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       starts_with(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).starts_with(__x); }
 
+      [[__gnu__::__nonnull__]]
       bool
       starts_with(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).starts_with(__x); }
@@ -3024,6 +3025,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       ends_with(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
 
+      [[__gnu__::__nonnull__]]
       bool
       ends_with(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
@@ -3038,6 +3040,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       contains(_CharT __x) const noexcept
       { return __sv_type(this->data(), this->size()).contains(__x); }
 
+      [[__gnu__::__nonnull__]]
       bool
       contains(const _CharT* __x) const noexcept
       { return __sv_type(this->data(), this->size()).contains(__x); }

diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view
index 30ff136b1cb725bee6c9b557429f201716adcc0a..5b96ffeecd6199000c45f04588d6f028d873af5d 100644 (file)
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -360,6 +360,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       starts_with(_CharT __x) const noexcept
       { return !this->empty() && traits_type::eq(this->front(), __x); }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       starts_with(const _CharT* __x) const noexcept
       { return this->starts_with(basic_string_view(__x)); }
@@ -377,6 +378,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       ends_with(_CharT __x) const noexcept
       { return !this->empty() && traits_type::eq(this->back(), __x); }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       ends_with(const _CharT* __x) const noexcept
       { return this->ends_with(basic_string_view(__x)); }
@@ -392,6 +394,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       contains(_CharT __x) const noexcept
       { return this->find(__x) != npos; }
 
+      [[__gnu__::__nonnull__]]
       constexpr bool
       contains(const _CharT* __x) const noexcept
       { return this->find(__x) != npos; }

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/nonnull.cc
new file mode 100644 (file)
index 0000000..e987cb7
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++23 -Wnonnull -O0" }
+// { dg-do compile { target c++23 } }
+
+#include <string>
+
+void
+test01(const std::string& s)
+{
+  s.contains((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.contains((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.contains(nullptr);              // { dg-warning "\\\[-Wnonnull" }
+}

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
new file mode 100644 (file)
index 0000000..1f2a156
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++20 -Wnonnull -O0" }
+// { dg-do compile { target c++20 } }
+
+#include <string>
+
+void
+test01(const std::string& s)
+{
+  s.ends_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.ends_with((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.ends_with(nullptr);                      // { dg-warning "\\\[-Wnonnull" }
+}

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
new file mode 100644 (file)
index 0000000..8514359
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++20 -Wnonnull -O0" }
+// { dg-do compile { target c++20 } }
+
+#include <string>
+
+void
+test01(const std::string& s)
+{
+  s.starts_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.starts_with((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.starts_with(nullptr);              // { dg-warning "\\\[-Wnonnull" }
+}

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/nonnull.cc
new file mode 100644 (file)
index 0000000..c0d274f
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++23 -Wnonnull -O0" }
+// { dg-do compile { target c++23 } }
+
+#include <string_view>
+
+void
+test01(std::string_view s)
+{
+  s.contains((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.contains((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.contains(nullptr);              // { dg-warning "\\\[-Wnonnull" }
+}

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/ends_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/ends_with/nonnull.cc
new file mode 100644 (file)
index 0000000..09a9997
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/ends_with/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++20 -Wnonnull -O0" }
+// { dg-do compile { target c++20 } }
+
+#include <string_view>
+
+void
+test01(std::string_view s)
+{
+  s.ends_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.ends_with((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.ends_with(nullptr);                      // { dg-warning "\\\[-Wnonnull" }
+}

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/starts_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/starts_with/nonnull.cc
new file mode 100644 (file)
index 0000000..c47f1da
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/starts_with/nonnull.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++20 -Wnonnull -O0" }
+// { dg-do compile { target c++20 } }
+
+#include <string_view>
+
+void
+test01(std::string_view s)
+{
+  s.starts_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
+  s.starts_with((char*)nullptr);       // { dg-warning "\\\[-Wnonnull" }
+  s.starts_with(nullptr);              // { dg-warning "\\\[-Wnonnull" }
+}