3 ms·

You're quoting from a footnote. The footnotes are not part of the normative text, so how you choose to interpret it is irrelevant. The actual definition of und

by pdw 3y ago

You're quoting from a footnote. The footnotes are not part of the normative text, so how you choose to interpret it is irrelevant. The actual definition of undefined behavior given by § 3.4.3 is: "behavior, upon use of a nonportable or erroneous program construct or of erroneous data, for which this International Standard imposes no requirements." Since no requirement is imposed, compilers can do as they want.

torstenvl 3y ago
> You're quoting from a footnote. The footnotes are not part of the normative text I am not quoting from a footnote. Footnote 1 pertains to § 1. Footnote 2 pertains to § 3.19.5. There are no footnotes pertaining to § 3.4.3. And do you have a citation for the proposition that footnotes or notes of any other kind are not normative?
- pdw 3y ago
  Apologies, it's a note, not a footnote. But notes in ISO standards aren't normative either. This is a general principle of ISO standards, see https://share.ansi.org/Shared%20Documents/Standards%20Activities/International%20Standardization/ISO/ISO_IEC_Directives_Part_2.pdf https://share.ansi.org/Shared%20Documents/Standards%20Activi...: > 6.5 Other informative elements > 6.5.1 Notes and examples integrated in the text > Notes and examples integrated in the text of a document shall only be used for giving additional information intended to assist the understanding or use of the document. They shall not contain requirements ("shall"; see 3.3.1 and Table H.1) or any information considered indispensable for the use of the document, e.g. instructions (imperative; see Table H.1), recommendations ("should"; see 3.3.2 and Table H.2) or permission ("may"; see Table H.3). Notes may be written as a statement of fact.
  - torstenvl 3y ago
    I don't view "You shall not do this" and "If you do this, it's meaningless" as identical statements. Besides, clang does the same thing with -std=c89, where this provision was emphatically not a note.

by pdw 3y ago

torstenvl 3y ago

> You're quoting from a footnote. The footnotes are not part of the normative text I am not quoting from a footnote. Footnote 1 pertains to § 1. Footnote 2 pertains to § 3.19.5. There are no footnotes pertaining to § 3.4.3. And do you have a citation for the proposition that footnotes or notes of any other kind are not normative?

pdw 3y ago
Apologies, it's a note, not a footnote. But notes in ISO standards aren't normative either. This is a general principle of ISO standards, see https://share.ansi.org/Shared%20Documents/Standards%20Activities/International%20Standardization/ISO/ISO_IEC_Directives_Part_2.pdf https://share.ansi.org/Shared%20Documents/Standards%20Activi...: > 6.5 Other informative elements > 6.5.1 Notes and examples integrated in the text > Notes and examples integrated in the text of a document shall only be used for giving additional information intended to assist the understanding or use of the document. They shall not contain requirements ("shall"; see 3.3.1 and Table H.1) or any information considered indispensable for the use of the document, e.g. instructions (imperative; see Table H.1), recommendations ("should"; see 3.3.2 and Table H.2) or permission ("may"; see Table H.3). Notes may be written as a statement of fact.
- torstenvl 3y ago
  I don't view "You shall not do this" and "If you do this, it's meaningless" as identical statements. Besides, clang does the same thing with -std=c89, where this provision was emphatically not a note.