tmp/tmpyxxdwm6m/{from.md → to.md}
RENAMED
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### [[basic]]: basics <a id="diff.basic">[[diff.basic]]</a>
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**Change:** C++ does not have “tentative definitions” as in C.
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-
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``` cpp
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int i;
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int i;
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```
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is valid in C, invalid in C++.
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-
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-
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``` cpp
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struct X { int i; struct X* next; };
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static struct X a;
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static struct X b = { 0, &a };
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static struct X a = { 1, &b };
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```
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**Rationale:** This avoids having different initialization rules for
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fundamental types and user-defined types. **Effect on original
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feature:** Deletion of semantically well-defined feature. Semantic
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transformation. In C++, the initializer for one of a set of
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mutually-referential file-local objects with static storage duration
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must invoke a function call to achieve the initialization. Seldom.
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**Change:** A `struct` is a scope in C++, not in C.
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``` cpp
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struct X {
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struct Y { int a; } b;
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};
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struct Y c;
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```
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is valid in C but not in C++, which would require `X::Y c;`.
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**Rationale:** Class scope is crucial to C++, and a struct is a class.
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**Effect on original feature:** Change to semantics of well-defined
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feature. Semantic transformation. C programs use `struct` extremely
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frequently, but the change is only noticeable when `struct`,
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enumeration, or enumerator names are referred to outside the `struct`.
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### [[basic]]: basics <a id="diff.basic">[[diff.basic]]</a>
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**Change:** C++ does not have “tentative definitions” as in C.
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+
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[*Example 1*:
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At file scope,
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``` cpp
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int i;
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int i;
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```
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is valid in C, invalid in C++.
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+
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— *end example*]
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This makes it impossible to define mutually referential file-local
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objects with static storage duration, if initializers are restricted to
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the syntactic forms of C.
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[*Example 2*:
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``` cpp
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struct X { int i; struct X* next; };
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static struct X a;
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static struct X b = { 0, &a };
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static struct X a = { 1, &b };
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```
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— *end example*]
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+
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**Rationale:** This avoids having different initialization rules for
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fundamental types and user-defined types. **Effect on original
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feature:** Deletion of semantically well-defined feature. Semantic
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transformation. In C++, the initializer for one of a set of
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mutually-referential file-local objects with static storage duration
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must invoke a function call to achieve the initialization. Seldom.
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+
**Change:** A `struct` is a scope in C++, not in C.
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+
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[*Example 3*:
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``` cpp
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struct X {
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struct Y { int a; } b;
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};
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struct Y c;
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```
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is valid in C but not in C++, which would require `X::Y c;`.
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+
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— *end example*]
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+
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**Rationale:** Class scope is crucial to C++, and a struct is a class.
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**Effect on original feature:** Change to semantics of well-defined
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feature. Semantic transformation. C programs use `struct` extremely
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frequently, but the change is only noticeable when `struct`,
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enumeration, or enumerator names are referred to outside the `struct`.
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