RFR: 8307160: [REDO] Enable the permissive- flag on the Microsoft Visual C compiler [v3]

[Julian Waters]

On Wed, 16 Aug 2023 19:22:01 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> Why initial patch was reverter using this comment: "unfortunately, did not prove to be as useful as expected"? What was the problem? What about the "pedantic" option which was added last time?

Hi, the problem was that gcc and clang are by default extremely strict with regards to conforming to C++, and the -pedantic flag simply made them so strict that it was impossible to compile the JDK with them. In an ideal world we'd be able to compile with -pedantic enabled, but that seems to be a lot of work required before that can be achieved, so it was reverted. In contrast, Visual C compiler is much too lax with what it allows you to get away with by default, so the permissive- flag is needed to make it match clang and gcc's default strictness. Additionally, permissive- is going to become the default on Visual C in the future, so we should add this as a flag to allow the JDK to be prepared when that time arrives

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PR Comment: https://git.openjdk.org/jdk/pull/15096#issuecomment-1681596804