[diff.cpp03] - C++14 → C++17

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@@ -4,11 +4,11 @@ This subclause lists the differences between C++and ISO C++03(ISO/IEC
 14882:2003, *Programming Languages — C++*), by the chapters of this
 document.
 ### Clause  [[lex]]: lexical conventions <a id="diff.cpp03.lex">[[diff.cpp03.lex]]</a>
-[[lex.pptoken]] **Change:** New kinds of string literals **Rationale:**
 Required for new features. **Effect on original feature:** Valid
 C++03code may fail to compile or produce different results in this
 International Standard. Specifically, macros named `R`, `u8`, `u8R`,
 `u`, `uR`, `U`, `UR`, or `LR` will not be expanded when adjacent to a
 string literal but will be interpreted as part of the string literal.
@@ -17,11 +17,11 @@ For example,
 ``` cpp
 #define u8 "abc"
 const char* s = u8"def";        // Previously "abcdef", now "def"
 ```
-[[lex.pptoken]] **Change:** User-defined literal string support
 **Rationale:** Required for new features. **Effect on original
 feature:** Valid C++03code may fail to compile or produce different
 results in this International Standard, as the following example
 illustrates.
@@ -30,32 +30,32 @@ illustrates.
 "hello"_x         // #1
 ```
 Previously, \#1 would have consisted of two separate preprocessing
 tokens and the macro `_x` would have been expanded. In this
-International Standard, \#1 consists of a single preprocessing tokens,
-so the macro is not expanded.
-[[lex.key]] **Change:** New keywords **Rationale:** Required for new
 features. **Effect on original feature:** Added to Table
 [[tab:keywords]], the following identifiers are new keywords: `alignas`,
 `alignof`, `char16_t`, `char32_t`, `constexpr`, `decltype`, `noexcept`,
 `nullptr`, `static_assert`, and `thread_local`. Valid C++03code using
 these identifiers is invalid in this International Standard.
-[[lex.icon]] **Change:** Type of integer literals **Rationale:** C99
 compatibility. **Effect on original feature:** Certain integer literals
 larger than can be represented by `long` could change from an unsigned
 integer type to `signed long long`.
 ### Clause  [[conv]]: standard conversions <a id="diff.cpp03.conv">[[diff.cpp03.conv]]</a>
 [[conv.ptr]] **Change:** Only literals are integer null pointer
-constants **Rationale:** Removing surprising interactions with templates
-and constant expressions **Effect on original feature:** Valid C++03code
-may fail to compile or produce different results in this International
-Standard, as the following example illustrates:
 ``` cpp
 void f(void *);  // #1
 void f(...);     // #2
 template<int N> void g() {
@@ -64,28 +64,40 @@ template<int N> void g() {
 ```
 ### Clause  [[expr]]: expressions <a id="diff.cpp03.expr">[[diff.cpp03.expr]]</a>
 [[expr.mul]] **Change:** Specify rounding for results of integer `/` and
-`%` **Rationale:** Increase portability, C99 compatibility. **Effect on
 original feature:** Valid C++03code that uses integer division rounds
 the result toward 0 or toward negative infinity, whereas this
 International Standard always rounds the result toward 0.
 ### Clause  [[dcl.dcl]]: declarations <a id="diff.cpp03.dcl.dcl">[[diff.cpp03.dcl.dcl]]</a>
-[[dcl.spec]] **Change:** Remove `auto` as a storage class specifier
 **Rationale:** New feature. **Effect on original feature:** Valid
 C++03code that uses the keyword `auto` as a storage class specifier may
 be invalid in this International Standard. In this International
 Standard, `auto` indicates that the type of a variable is to be deduced
 from its initializer expression.
 ### Clause  [[dcl.decl]]: declarators <a id="diff.cpp03.dcl.decl">[[diff.cpp03.dcl.decl]]</a>
 [[dcl.init.list]] **Change:** Narrowing restrictions in aggregate
-initializers **Rationale:** Catches bugs. **Effect on original
 feature:** Valid C++03code may fail to compile in this International
 Standard. For example, the following code is valid in C++03but invalid
 in this International Standard because `double` to `int` is a narrowing
 conversion:
@@ -105,27 +117,24 @@ expression that is not potentially evaluated) becomes ill-formed.
 [[class.dtor]] (destructors) **Change:** User-declared destructors have
 an implicit exception specification. **Rationale:** Clarification of
 destructor requirements. **Effect on original feature:** Valid C++03code
 may execute differently in this International Standard. In particular,
-destructors that throw exceptions will call `std::terminate()` (without
-calling `std::unexpected()`) if their exception specification is
-`noexcept` or `noexcept(true)`. For a throwing virtual destructor of a
-derived class, `std::terminate()` can be avoided only if the base class
-virtual destructor has an exception specification that is not `noexcept`
-and not `noexcept(true)`.
 ### Clause  [[temp]]: templates <a id="diff.cpp03.temp">[[diff.cpp03.temp]]</a>
-[[temp.param]] **Change:** Remove `export` **Rationale:** No
 implementation consensus. **Effect on original feature:** A valid
 C++03declaration containing `export` is ill-formed in this International
 Standard.
 [[temp.arg]] **Change:** Remove whitespace requirement for nested
-closing template right angle brackets **Rationale:** Considered a
-persistent but minor annoyance. Template aliases representing nonclass
 types would exacerbate whitespace issues. **Effect on original
 feature:** Change to semantics of well-defined expression. A valid
 C++03expression containing a right angle bracket (“`>`”) followed
 immediately by another right angle bracket may now be treated as closing
 two templates. For example, the following code is valid in C++03because
@@ -137,26 +146,26 @@ template <class T> struct X { };
 template <int N> struct Y { };
 X< Y< 1 >> 2 > > x;
 ```
 [[temp.dep.candidate]] **Change:** Allow dependent calls of functions
-with internal linkage **Rationale:** Overly constrained, simplify
 overload resolution rules. **Effect on original feature:** A valid
 C++03program could get a different result than this International
 Standard.
 ### Clause  [[library]]: library introduction <a id="diff.cpp03.library">[[diff.cpp03.library]]</a>
-[[library]] – [[thread]] **Change:** New reserved identifiers
 **Rationale:** Required by new features. **Effect on original feature:**
 Valid C++03code that uses any identifiers added to the C++standard
 library by this International Standard may fail to compile or produce
-different results in This International Standard. A comprehensive list
 of identifiers used by the C++standard library can be found in the Index
 of Library Names in this International Standard.
-[[headers]] **Change:** New headers **Rationale:** New functionality.
 **Effect on original feature:** The following C++headers are new:
 `<array>`, `<atomic>`, `<chrono>`, `<codecvt>`, `<condition_variable>`,
 `<forward_list>`, `<future>`, `<initializer_list>`, `<mutex>`,
 `<random>`, `<ratio>`, `<regex>`, `<scoped_allocator>`,
 `<system_error>`, `<thread>`, `<tuple>`, `<typeindex>`,
@@ -171,26 +180,26 @@ in this International Standard.
 `swap` moved to a different header **Rationale:** Remove dependency on
 `<algorithm>` for `swap`. **Effect on original feature:** Valid
 C++03code that has been compiled expecting swap to be in `<algorithm>`
 may have to instead include `<utility>`.
-[[namespace.posix]] **Change:** New reserved namespace **Rationale:**
 New functionality. **Effect on original feature:** The global namespace
 `posix` is now reserved for standardization. Valid C++03code that uses a
 top-level namespace `posix` may be invalid in this International
 Standard.
 [[res.on.macro.definitions]] **Change:** Additional restrictions on
-macro names **Rationale:** Avoid hard to diagnose or non-portable
 constructs. **Effect on original feature:** Names of attribute
 identifiers may not be used as macro names. Valid C++ 2003 code that
 defines `override`, `final`, `carries_dependency`, or `noreturn` as
 macros is invalid in this International Standard.
 ### Clause  [[language.support]]: language support library <a id="diff.cpp03.language.support">[[diff.cpp03.language.support]]</a>
-[[new.delete.single]] **Change:** Linking `new` and `delete` operators
 **Rationale:** The two throwing single-object signatures of
 `operator new` and `operator delete` are now specified to form the base
 functionality for the other operators. This clarifies that replacing
 just these two signatures changes others, even if they are not
 explicitly changed. **Effect on original feature:** Valid C++03code that
@@ -216,71 +225,70 @@ void operator delete(void* ptr) throw() {
 int main() {
   int* i = new int;
   delete i;                     // single-object delete
   int* a = new int[3];
   delete [] a;                  // array delete
-  return 0;
 }
 ```
 [[new.delete.single]] **Change:** `operator new` may throw exceptions
-other than `std::bad_alloc` **Rationale:** Consistent application of
 `noexcept`. **Effect on original feature:** Valid C++03code that assumes
 that global `operator new` only throws `std::bad_alloc` may execute
 differently in this International Standard.
 ### Clause  [[diagnostics]]: diagnostics library <a id="diff.cpp03.diagnostics">[[diff.cpp03.diagnostics]]</a>
-[[errno]] **Change:** Thread-local error numbers **Rationale:** Support
 for new thread facilities. **Effect on original feature:** Valid but
 implementation-specific C++03code that relies on `errno` being the same
 across threads may change behavior in this International Standard.
 ### Clause  [[utilities]]: general utilities library <a id="diff.cpp03.utilities">[[diff.cpp03.utilities]]</a>
 [[util.dynamic.safety]] **Change:** Minimal support for
-garbage-collected regions **Rationale:** Required by new feature.
 **Effect on original feature:** Valid C++03code, compiled without
 traceable pointer support, that interacts with newer C++code using
 regions declared reachable may have different runtime behavior.
 [[refwrap]], [[arithmetic.operations]], [[comparisons]],
-[[logical.operations]], [[bitwise.operations]], [[negators]] **Change:**
-Standard function object types no longer derived from
-`std::unary_function` or `std::binary_function` **Rationale:**
-Superseded by new feature. **Effect on original feature:** Valid
-C++03code that depends on function object types being derived from
-`unary_function` or `binary_function` will execute differently in this
-International Standard.
 ### Clause  [[strings]]: strings library <a id="diff.cpp03.strings">[[diff.cpp03.strings]]</a>
 [[string.classes]] **Change:** `basic_string` requirements no longer
-allow reference-counted strings **Rationale:** Invalidation is subtly
 different with reference-counted strings. This change regularizes
 behavior for this International Standard. **Effect on original
 feature:** Valid C++03code may execute differently in this International
 Standard.
-[[string.require]] **Change:** Loosen `basic_string` invalidation rules
 **Rationale:** Allow small-string optimization. **Effect on original
 feature:** Valid C++03code may execute differently in this International
 Standard. Some `const` member functions, such as `data` and `c_str`, no
 longer invalidate iterators.
 ### Clause  [[containers]]: containers library <a id="diff.cpp03.containers">[[diff.cpp03.containers]]</a>
 [[container.requirements]] **Change:** Complexity of `size()` member
-functions now constant **Rationale:** Lack of specification of
 complexity of `size()` resulted in divergent implementations with
 inconsistent performance characteristics. **Effect on original
 feature:** Some container implementations that conform to C++03may not
 conform to the specified `size()` requirements in this International
 Standard. Adjusting containers such as `std::list` to the stricter
 requirements may require incompatible changes.
-[[container.requirements]] **Change:** Requirements change: relaxation
 **Rationale:** Clarification. **Effect on original feature:** Valid
 C++03code that attempts to meet the specified container requirements may
 now be over-specified. Code that attempted to be portable across
 containers may need to be adjusted as follows:
@@ -288,17 +296,17 @@ containers may need to be adjusted as follows:
   `size() == 0`;
 - not all containers are empty after construction (`array`);
 - not all containers have constant complexity for `swap()` (`array`).
 [[container.requirements]] **Change:** Requirements change: default
-constructible **Rationale:** Clarification of container requirements.
 **Effect on original feature:** Valid C++03code that attempts to
 explicitly instantiate a container using a user-defined type with no
 default constructor may fail to compile.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
-changes: from `void` return types **Rationale:** Old signature threw
 away useful information that may be expensive to recalculate. **Effect
 on original feature:** The following member functions have changed:
 - `erase(iter)` for `set`, `multiset`, `map`, `multimap`
 - `erase(begin, end)` for `set`, `multiset`, `map`, `multimap`
@@ -308,57 +316,56 @@ on original feature:** The following member functions have changed:
 Valid C++03code that relies on these functions returning `void` (e.g.,
 code that creates a pointer to member function that points to one of
 these functions) will fail to compile with this International Standard.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
-changes: from `iterator` to `const_iterator` parameters **Rationale:**
-Overspecification. *Effects:* The signatures of the following member
-functions changed from taking an `iterator` to taking a
 `const_iterator`:
 - `insert(iter, val)` for `vector`, `deque`, `list`, `set`, `multiset`,
   `map`, `multimap`
 - `insert(pos, beg, end)` for `vector`, `deque`, `list`, `forward_list`
-- `erase(iter)` for `set`, `multiset`, `map`, `multimap`
 - `erase(begin, end)` for `set`, `multiset`, `map`, `multimap`
 - all forms of `list::splice`
 - all forms of `list::merge`
 Valid C++03code that uses these functions may fail to compile with this
 International Standard.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
-changes: `resize` **Rationale:** Performance, compatibility with move
 semantics. **Effect on original feature:** For `vector`, `deque`, and
 `list` the fill value passed to `resize` is now passed by reference
 instead of by value, and an additional overload of `resize` has been
 added. Valid C++03code that uses this function may fail to compile with
 this International Standard.
 ### Clause  [[algorithms]]: algorithms library <a id="diff.cpp03.algorithms">[[diff.cpp03.algorithms]]</a>
 [[algorithms.general]] **Change:** Result state of inputs after
-application of some algorithms **Rationale:** Required by new feature.
 **Effect on original feature:** A valid C++03program may detect that an
 object with a valid but unspecified state has a different valid but
 unspecified state with this International Standard. For example,
 `std::remove` and `std::remove_if` may leave the tail of the input
 sequence with a different set of values than previously.
 ### Clause  [[numerics]]: numerics library <a id="diff.cpp03.numerics">[[diff.cpp03.numerics]]</a>
 [[complex.numbers]] **Change:** Specified representation of complex
-numbers **Rationale:** Compatibility with C99. **Effect on original
 feature:** Valid C++03code that uses implementation-specific knowledge
 about the binary representation of the required template specializations
 of `std::complex` may not be compatible with this International
 Standard.
-### Clause  [[input.output]]: Input/output library <a id="diff.cpp03.input.output">[[diff.cpp03.input.output]]</a>
 [[istream::sentry]], [[ostream::sentry]], [[iostate.flags]] **Change:**
-Specify use of explicit in existing boolean conversion operators
 **Rationale:** Clarify intentions, avoid workarounds. **Effect on
 original feature:** Valid C++03code that relies on implicit boolean
 conversions will fail to compile with this International Standard. Such
 conversions occur in the following conditions:
@@ -367,20 +374,20 @@ conversions occur in the following conditions:
 - returning a value from a function with a return type of `bool`;
 - initializing members of type `bool` via aggregate initialization;
 - initializing a `const bool&` which would bind to a temporary.
 [[ios::failure]] **Change:** Change base class of
-`std::ios_base::failure` **Rationale:** More detailed error messages.
 **Effect on original feature:** `std::ios_base::failure` is no longer
 derived directly from `std::exception`, but is now derived from
 `std::system_error`, which in turn is derived from `std::runtime_error`.
 Valid C++03code that assumes that `std::ios_base::failure` is derived
 directly from `std::exception` may execute differently in this
 International Standard.
 [[ios.base]] **Change:** Flag types in `std::ios_base` are now bitmasks
-with values defined as constexpr static members **Rationale:** Required
 for new features. **Effect on original feature:** Valid C++03code that
 relies on `std::ios_base` flag types being represented as `std::bitset`
 or as an integer type may fail to compile with this International
 Standard. For example:
@@ -388,9 +395,8 @@ Standard. For example:
 #include <iostream>
 int main() {
   int flag = std::ios_base::hex;
   std::cout.setf(flag);         // error: setf does not take argument of type int
-  return 0;
 }
 ```

 14882:2003, *Programming Languages — C++*), by the chapters of this
 document.
 ### Clause  [[lex]]: lexical conventions <a id="diff.cpp03.lex">[[diff.cpp03.lex]]</a>
+[[lex.pptoken]] **Change:** New kinds of string literals. **Rationale:**
 Required for new features. **Effect on original feature:** Valid
 C++03code may fail to compile or produce different results in this
 International Standard. Specifically, macros named `R`, `u8`, `u8R`,
 `u`, `uR`, `U`, `UR`, or `LR` will not be expanded when adjacent to a
 string literal but will be interpreted as part of the string literal.
 ``` cpp
 #define u8 "abc"
 const char* s = u8"def";        // Previously "abcdef", now "def"
 ```
+[[lex.pptoken]] **Change:** User-defined literal string support.
 **Rationale:** Required for new features. **Effect on original
 feature:** Valid C++03code may fail to compile or produce different
 results in this International Standard, as the following example
 illustrates.
 "hello"_x         // #1
 ```
 Previously, \#1 would have consisted of two separate preprocessing
 tokens and the macro `_x` would have been expanded. In this
+International Standard, \#1 consists of a single preprocessing token, so
+the macro is not expanded.
+[[lex.key]] **Change:** New keywords. **Rationale:** Required for new
 features. **Effect on original feature:** Added to Table
 [[tab:keywords]], the following identifiers are new keywords: `alignas`,
 `alignof`, `char16_t`, `char32_t`, `constexpr`, `decltype`, `noexcept`,
 `nullptr`, `static_assert`, and `thread_local`. Valid C++03code using
 these identifiers is invalid in this International Standard.
+[[lex.icon]] **Change:** Type of integer literals. **Rationale:** C99
 compatibility. **Effect on original feature:** Certain integer literals
 larger than can be represented by `long` could change from an unsigned
 integer type to `signed long long`.
 ### Clause  [[conv]]: standard conversions <a id="diff.cpp03.conv">[[diff.cpp03.conv]]</a>
 [[conv.ptr]] **Change:** Only literals are integer null pointer
+constants. **Rationale:** Removing surprising interactions with
+templates and constant expressions. **Effect on original feature:**
+Valid C++03code may fail to compile or produce different results in this
+International Standard, as the following example illustrates:
 ``` cpp
 void f(void *);  // #1
 void f(...);     // #2
 template<int N> void g() {
 ```
 ### Clause  [[expr]]: expressions <a id="diff.cpp03.expr">[[diff.cpp03.expr]]</a>
 [[expr.mul]] **Change:** Specify rounding for results of integer `/` and
+`%`. **Rationale:** Increase portability, C99 compatibility. **Effect on
 original feature:** Valid C++03code that uses integer division rounds
 the result toward 0 or toward negative infinity, whereas this
 International Standard always rounds the result toward 0.
+[[expr.log.and]] **Change:** `&&` is valid in a *type-name*.
+**Rationale:** Required for new features. **Effect on original
+feature:** Valid C++03code may fail to compile or produce different
+results in this International Standard, as the following example
+illustrates:
+``` cpp
+bool b1 = new int && false;           // previously false, now ill-formed
+struct S { operator int(); };
+bool b2 = &S::operator int && false;  // previously false, now ill-formed
+```
 ### Clause  [[dcl.dcl]]: declarations <a id="diff.cpp03.dcl.dcl">[[diff.cpp03.dcl.dcl]]</a>
+[[dcl.spec]] **Change:** Remove `auto` as a storage class specifier.
 **Rationale:** New feature. **Effect on original feature:** Valid
 C++03code that uses the keyword `auto` as a storage class specifier may
 be invalid in this International Standard. In this International
 Standard, `auto` indicates that the type of a variable is to be deduced
 from its initializer expression.
 ### Clause  [[dcl.decl]]: declarators <a id="diff.cpp03.dcl.decl">[[diff.cpp03.dcl.decl]]</a>
 [[dcl.init.list]] **Change:** Narrowing restrictions in aggregate
+initializers. **Rationale:** Catches bugs. **Effect on original
 feature:** Valid C++03code may fail to compile in this International
 Standard. For example, the following code is valid in C++03but invalid
 in this International Standard because `double` to `int` is a narrowing
 conversion:
 [[class.dtor]] (destructors) **Change:** User-declared destructors have
 an implicit exception specification. **Rationale:** Clarification of
 destructor requirements. **Effect on original feature:** Valid C++03code
 may execute differently in this International Standard. In particular,
+destructors that throw exceptions will call `std::terminate` (without
+calling `std::unexpected`) if their exception specification is
+non-throwing.
 ### Clause  [[temp]]: templates <a id="diff.cpp03.temp">[[diff.cpp03.temp]]</a>
+[[temp.param]] **Change:** Remove `export`. **Rationale:** No
 implementation consensus. **Effect on original feature:** A valid
 C++03declaration containing `export` is ill-formed in this International
 Standard.
 [[temp.arg]] **Change:** Remove whitespace requirement for nested
+closing template right angle brackets. **Rationale:** Considered a
+persistent but minor annoyance. Template aliases representing non-class
 types would exacerbate whitespace issues. **Effect on original
 feature:** Change to semantics of well-defined expression. A valid
 C++03expression containing a right angle bracket (“`>`”) followed
 immediately by another right angle bracket may now be treated as closing
 two templates. For example, the following code is valid in C++03because
 template <int N> struct Y { };
 X< Y< 1 >> 2 > > x;
 ```
 [[temp.dep.candidate]] **Change:** Allow dependent calls of functions
+with internal linkage. **Rationale:** Overly constrained, simplify
 overload resolution rules. **Effect on original feature:** A valid
 C++03program could get a different result than this International
 Standard.
 ### Clause  [[library]]: library introduction <a id="diff.cpp03.library">[[diff.cpp03.library]]</a>
+[[library]] – [[thread]] **Change:** New reserved identifiers.
 **Rationale:** Required by new features. **Effect on original feature:**
 Valid C++03code that uses any identifiers added to the C++standard
 library by this International Standard may fail to compile or produce
+different results in this International Standard. A comprehensive list
 of identifiers used by the C++standard library can be found in the Index
 of Library Names in this International Standard.
+[[headers]] **Change:** New headers. **Rationale:** New functionality.
 **Effect on original feature:** The following C++headers are new:
 `<array>`, `<atomic>`, `<chrono>`, `<codecvt>`, `<condition_variable>`,
 `<forward_list>`, `<future>`, `<initializer_list>`, `<mutex>`,
 `<random>`, `<ratio>`, `<regex>`, `<scoped_allocator>`,
 `<system_error>`, `<thread>`, `<tuple>`, `<typeindex>`,
 `swap` moved to a different header **Rationale:** Remove dependency on
 `<algorithm>` for `swap`. **Effect on original feature:** Valid
 C++03code that has been compiled expecting swap to be in `<algorithm>`
 may have to instead include `<utility>`.
+[[namespace.posix]] **Change:** New reserved namespace. **Rationale:**
 New functionality. **Effect on original feature:** The global namespace
 `posix` is now reserved for standardization. Valid C++03code that uses a
 top-level namespace `posix` may be invalid in this International
 Standard.
 [[res.on.macro.definitions]] **Change:** Additional restrictions on
+macro names. **Rationale:** Avoid hard to diagnose or non-portable
 constructs. **Effect on original feature:** Names of attribute
 identifiers may not be used as macro names. Valid C++ 2003 code that
 defines `override`, `final`, `carries_dependency`, or `noreturn` as
 macros is invalid in this International Standard.
 ### Clause  [[language.support]]: language support library <a id="diff.cpp03.language.support">[[diff.cpp03.language.support]]</a>
+[[new.delete.single]] **Change:** Linking `new` and `delete` operators.
 **Rationale:** The two throwing single-object signatures of
 `operator new` and `operator delete` are now specified to form the base
 functionality for the other operators. This clarifies that replacing
 just these two signatures changes others, even if they are not
 explicitly changed. **Effect on original feature:** Valid C++03code that
 int main() {
   int* i = new int;
   delete i;                     // single-object delete
   int* a = new int[3];
   delete [] a;                  // array delete
 }
 ```
 [[new.delete.single]] **Change:** `operator new` may throw exceptions
+other than `std::bad_alloc`. **Rationale:** Consistent application of
 `noexcept`. **Effect on original feature:** Valid C++03code that assumes
 that global `operator new` only throws `std::bad_alloc` may execute
 differently in this International Standard.
 ### Clause  [[diagnostics]]: diagnostics library <a id="diff.cpp03.diagnostics">[[diff.cpp03.diagnostics]]</a>
+[[errno]] **Change:** Thread-local error numbers. **Rationale:** Support
 for new thread facilities. **Effect on original feature:** Valid but
 implementation-specific C++03code that relies on `errno` being the same
 across threads may change behavior in this International Standard.
 ### Clause  [[utilities]]: general utilities library <a id="diff.cpp03.utilities">[[diff.cpp03.utilities]]</a>
 [[util.dynamic.safety]] **Change:** Minimal support for
+garbage-collected regions. **Rationale:** Required by new feature.
 **Effect on original feature:** Valid C++03code, compiled without
 traceable pointer support, that interacts with newer C++code using
 regions declared reachable may have different runtime behavior.
 [[refwrap]], [[arithmetic.operations]], [[comparisons]],
+[[logical.operations]], [[bitwise.operations]], [[depr.negators]]
+**Change:** Standard function object types no longer derived from
+`std::unary_function` or `std::binary_function`. **Rationale:**
+Superseded by new feature; `unary_function` and `binary_function` are no
+longer defined. **Effect on original feature:** Valid C++03code that
+depends on function object types being derived from `unary_function` or
+`binary_function` may fail to compile in this International Standard.
 ### Clause  [[strings]]: strings library <a id="diff.cpp03.strings">[[diff.cpp03.strings]]</a>
 [[string.classes]] **Change:** `basic_string` requirements no longer
+allow reference-counted strings. **Rationale:** Invalidation is subtly
 different with reference-counted strings. This change regularizes
 behavior for this International Standard. **Effect on original
 feature:** Valid C++03code may execute differently in this International
 Standard.
+[[string.require]] **Change:** Loosen `basic_string` invalidation rules.
 **Rationale:** Allow small-string optimization. **Effect on original
 feature:** Valid C++03code may execute differently in this International
 Standard. Some `const` member functions, such as `data` and `c_str`, no
 longer invalidate iterators.
 ### Clause  [[containers]]: containers library <a id="diff.cpp03.containers">[[diff.cpp03.containers]]</a>
 [[container.requirements]] **Change:** Complexity of `size()` member
+functions now constant. **Rationale:** Lack of specification of
 complexity of `size()` resulted in divergent implementations with
 inconsistent performance characteristics. **Effect on original
 feature:** Some container implementations that conform to C++03may not
 conform to the specified `size()` requirements in this International
 Standard. Adjusting containers such as `std::list` to the stricter
 requirements may require incompatible changes.
+[[container.requirements]] **Change:** Requirements change: relaxation.
 **Rationale:** Clarification. **Effect on original feature:** Valid
 C++03code that attempts to meet the specified container requirements may
 now be over-specified. Code that attempted to be portable across
 containers may need to be adjusted as follows:
   `size() == 0`;
 - not all containers are empty after construction (`array`);
 - not all containers have constant complexity for `swap()` (`array`).
 [[container.requirements]] **Change:** Requirements change: default
+constructible. **Rationale:** Clarification of container requirements.
 **Effect on original feature:** Valid C++03code that attempts to
 explicitly instantiate a container using a user-defined type with no
 default constructor may fail to compile.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
+changes: from `void` return types. **Rationale:** Old signature threw
 away useful information that may be expensive to recalculate. **Effect
 on original feature:** The following member functions have changed:
 - `erase(iter)` for `set`, `multiset`, `map`, `multimap`
 - `erase(begin, end)` for `set`, `multiset`, `map`, `multimap`
 Valid C++03code that relies on these functions returning `void` (e.g.,
 code that creates a pointer to member function that points to one of
 these functions) will fail to compile with this International Standard.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
+changes: from `iterator` to `const_iterator` parameters. **Rationale:**
+Overspecification. **Effect on original feature:** The signatures of the
+following member functions changed from taking an `iterator` to taking a
 `const_iterator`:
 - `insert(iter, val)` for `vector`, `deque`, `list`, `set`, `multiset`,
   `map`, `multimap`
 - `insert(pos, beg, end)` for `vector`, `deque`, `list`, `forward_list`
 - `erase(begin, end)` for `set`, `multiset`, `map`, `multimap`
 - all forms of `list::splice`
 - all forms of `list::merge`
 Valid C++03code that uses these functions may fail to compile with this
 International Standard.
 [[sequence.reqmts]], [[associative.reqmts]] **Change:** Signature
+changes: `resize`. **Rationale:** Performance, compatibility with move
 semantics. **Effect on original feature:** For `vector`, `deque`, and
 `list` the fill value passed to `resize` is now passed by reference
 instead of by value, and an additional overload of `resize` has been
 added. Valid C++03code that uses this function may fail to compile with
 this International Standard.
 ### Clause  [[algorithms]]: algorithms library <a id="diff.cpp03.algorithms">[[diff.cpp03.algorithms]]</a>
 [[algorithms.general]] **Change:** Result state of inputs after
+application of some algorithms. **Rationale:** Required by new feature.
 **Effect on original feature:** A valid C++03program may detect that an
 object with a valid but unspecified state has a different valid but
 unspecified state with this International Standard. For example,
 `std::remove` and `std::remove_if` may leave the tail of the input
 sequence with a different set of values than previously.
 ### Clause  [[numerics]]: numerics library <a id="diff.cpp03.numerics">[[diff.cpp03.numerics]]</a>
 [[complex.numbers]] **Change:** Specified representation of complex
+numbers. **Rationale:** Compatibility with C99. **Effect on original
 feature:** Valid C++03code that uses implementation-specific knowledge
 about the binary representation of the required template specializations
 of `std::complex` may not be compatible with this International
 Standard.
+### Clause  [[input.output]]: input/output library <a id="diff.cpp03.input.output">[[diff.cpp03.input.output]]</a>
 [[istream::sentry]], [[ostream::sentry]], [[iostate.flags]] **Change:**
+Specify use of `explicit` in existing boolean conversion functions.
 **Rationale:** Clarify intentions, avoid workarounds. **Effect on
 original feature:** Valid C++03code that relies on implicit boolean
 conversions will fail to compile with this International Standard. Such
 conversions occur in the following conditions:
 - returning a value from a function with a return type of `bool`;
 - initializing members of type `bool` via aggregate initialization;
 - initializing a `const bool&` which would bind to a temporary.
 [[ios::failure]] **Change:** Change base class of
+`std::ios_base::failure`. **Rationale:** More detailed error messages.
 **Effect on original feature:** `std::ios_base::failure` is no longer
 derived directly from `std::exception`, but is now derived from
 `std::system_error`, which in turn is derived from `std::runtime_error`.
 Valid C++03code that assumes that `std::ios_base::failure` is derived
 directly from `std::exception` may execute differently in this
 International Standard.
 [[ios.base]] **Change:** Flag types in `std::ios_base` are now bitmasks
+with values defined as constexpr static members. **Rationale:** Required
 for new features. **Effect on original feature:** Valid C++03code that
 relies on `std::ios_base` flag types being represented as `std::bitset`
 or as an integer type may fail to compile with this International
 Standard. For example:
 #include <iostream>
 int main() {
   int flag = std::ios_base::hex;
   std::cout.setf(flag);         // error: setf does not take argument of type int
 }
 ```

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