[beta] another round of backports for 1.42#69748

Merged

bors merged 8 commits intorust-lang:betafrom

Mark-Simulacrum:beta-next

Mar 6, 2020

Commits on Mar 5, 2020

Fix a leak in `DiagnosticBuilder::into_diagnostic`.

nnethercote
authored and
Mark-Simulacrum
committed

Commits on Mar 6, 2020

stash API: remove panic to fix ICE.

Centril
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Mark-Simulacrum
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Do not ICE on invalid type node

LeSeulArtichaut
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Mark-Simulacrum
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Add regression test

LeSeulArtichaut
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Mark-Simulacrum
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Backport only: avoid ICE on bad placeholder type

estebank
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Mark-Simulacrum
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add regression test for issue #68794

brainlock
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Mark-Simulacrum
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Update compiler-builtins to 0.1.25

tmandry
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Mark-Simulacrum
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Backport release notes onto beta
Mark-Simulacrum
committed