From Jason Turner

[diff.stat]

C++17 → C++20 2.6 KB 34 lines
Current Draft | LaTeX Source
Archived: C++17 | C++20
Markdown: C++17 | C++20
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  1. tmp/tmpi1jsoj5l/{from.md → to.md} +15 -16
tmp/tmpi1jsoj5l/{from.md → to.md} RENAMED
@@ -1,23 +1,22 @@
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- ### Clause [[stmt.stmt]]: statements <a id="diff.stat">[[diff.stat]]</a>
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- [[stmt.switch]], [[stmt.goto]] **Change:** It is now invalid to jump
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- past a declaration with explicit or implicit initializer (except across
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- entire block not entered). **Rationale:** Constructors used in
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- initializers may allocate resources which need to be de-allocated upon
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- leaving the block. Allowing jump past initializers would require
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- complicated runtime determination of allocation. Furthermore, any use of
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- the uninitialized object could be a disaster. With this simple
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- compile-time rule, C++assures that if an initialized variable is in
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- scope, then it has assuredly been initialized. **Effect on original
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- feature:** Deletion of semantically well-defined feature. Semantic
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- transformation. Seldom.
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- [[stmt.return]] **Change:** It is now invalid to return (explicitly or
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- implicitly) from a function which is declared to return a value without
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- actually returning a value. **Rationale:** The caller and callee may
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- assume fairly elaborate return-value mechanisms for the return of class
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  objects. If some flow paths execute a return without specifying any
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  value, the implementation must embody many more complications. Besides,
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  promising to return a value of a given type, and then not returning such
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  a value, has always been recognized to be a questionable practice,
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  tolerated only because very-old C had no distinction between void
 
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+ ### [[stmt.stmt]]: statements <a id="diff.stat">[[diff.stat]]</a>
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+ **Change:** It is now invalid to jump past a declaration with explicit
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+ or implicit initializer (except across entire block not entered).
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+ **Rationale:** Constructors used in initializers may allocate resources
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+ which need to be de-allocated upon leaving the block. Allowing jump past
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+ initializers would require complicated runtime determination of
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+ allocation. Furthermore, any use of the uninitialized object could be a
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+ disaster. With this simple compile-time rule, C++ assures that if an
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+ initialized variable is in scope, then it has assuredly been
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+ initialized. **Effect on original feature:** Deletion of semantically
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+ well-defined feature. Semantic transformation. Seldom.
 
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+ **Change:** It is now invalid to return (explicitly or implicitly) from
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+ a function which is declared to return a value without actually
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+ returning a value. **Rationale:** The caller and callee may assume
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+ fairly elaborate return-value mechanisms for the return of class
18
  objects. If some flow paths execute a return without specifying any
19
  value, the implementation must embody many more complications. Besides,
20
  promising to return a value of a given type, and then not returning such
21
  a value, has always been recognized to be a questionable practice,
22
  tolerated only because very-old C had no distinction between void