From Jason Turner

[diff.cpp03.lex]

C++17 → C++20 3.4 KB 48 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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C++ Weekly: Ep 182

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  1. tmp/tmpi1rfxmgi/{from.md → to.md} +21 -23
tmp/tmpi1rfxmgi/{from.md → to.md} RENAMED
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- ### Clause [[lex]]: lexical conventions <a id="diff.cpp03.lex">[[diff.cpp03.lex]]</a>
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- [[lex.pptoken]] **Change:** New kinds of string literals. **Rationale:**
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- Required for new features. **Effect on original feature:** Valid
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- C++03code may fail to compile or produce different results in this
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- International Standard. Specifically, macros named `R`, `u8`, `u8R`,
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- `u`, `uR`, `U`, `UR`, or `LR` will not be expanded when adjacent to a
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- string literal but will be interpreted as part of the string literal.
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- For example,
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  ``` cpp
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  #define u8 "abc"
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  const char* s = u8"def"; // Previously "abcdef", now "def"
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  ```
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- [[lex.pptoken]] **Change:** User-defined literal string support.
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- **Rationale:** Required for new features. **Effect on original
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- feature:** Valid C++03code may fail to compile or produce different
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- results in this International Standard, as the following example
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- illustrates.
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  ``` cpp
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  #define _x "there"
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  "hello"_x // #1
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  ```
@@ -27,17 +25,17 @@ illustrates.
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  Previously, \#1 would have consisted of two separate preprocessing
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  tokens and the macro `_x` would have been expanded. In this
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  International Standard, \#1 consists of a single preprocessing token, so
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  the macro is not expanded.
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- [[lex.key]] **Change:** New keywords. **Rationale:** Required for new
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- features. **Effect on original feature:** Added to Table 
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- [[tab:keywords]], the following identifiers are new keywords: `alignas`,
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- `alignof`, `char16_t`, `char32_t`, `constexpr`, `decltype`, `noexcept`,
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- `nullptr`, `static_assert`, and `thread_local`. Valid C++03code using
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- these identifiers is invalid in this International Standard.
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- [[lex.icon]] **Change:** Type of integer literals. **Rationale:** C99
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- compatibility. **Effect on original feature:** Certain integer literals
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- larger than can be represented by `long` could change from an unsigned
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- integer type to `signed long long`.
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+ ### [[lex]]: lexical conventions <a id="diff.cpp03.lex">[[diff.cpp03.lex]]</a>
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+ **Change:** New kinds of *string-literal*s. **Rationale:** Required for
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+ new features. **Effect on original feature:** Valid C++03 code may fail
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+ to compile or produce different results in this International Standard.
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+ Specifically, macros named `R`, `u8`, `u8R`, `u`, `uR`, `U`, `UR`, or
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+ `LR` will not be expanded when adjacent to a *string-literal* but will
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+ be interpreted as part of the *string-literal*. For example:
 
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  ``` cpp
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  #define u8 "abc"
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  const char* s = u8"def"; // Previously "abcdef", now "def"
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  ```
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+ **Change:** User-defined literal string support. **Rationale:** Required
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+ for new features. **Effect on original feature:** Valid C++03 code may
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+ fail to compile or produce different results in this International
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+ Standard. For example:
 
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  ``` cpp
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  #define _x "there"
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  "hello"_x // #1
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  ```
 
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  Previously, \#1 would have consisted of two separate preprocessing
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  tokens and the macro `_x` would have been expanded. In this
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  International Standard, \#1 consists of a single preprocessing token, so
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  the macro is not expanded.
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+ **Change:** New keywords. **Rationale:** Required for new features.
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+ **Effect on original feature:** Added to [[lex.key]], the following
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+ identifiers are new keywords: `alignas`, `alignof`, `char16_t`,
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+ `char32_t`, `constexpr`, `decltype`, `noexcept`, `nullptr`,
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+ `static_assert`, and `thread_local`. Valid C++03 code using these
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+ identifiers is invalid in this International Standard.
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+ **Change:** Type of integer literals. **Rationale:** C99 compatibility.
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+ **Effect on original feature:** Certain integer literals larger than can
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+ be represented by `long` could change from an unsigned integer type to
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+ `signed long long`.
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