…ng the `-C instrument-coverage` flag.

Respond to PR comments.

fixes rust-lang#100563

emit the first 3 errors and duplicated diagnostic information
using take of iterator for the first third return
	modified:   compiler/rustc_typeck/src/check/coercion.rs
	new file:   src/test/ui/typeck/issue-100285.rs
	new file:   src/test/ui/typeck/issue-100285.stderr

…rochenkov

when there are 3 or more return statements in the loop

emit the first 3 errors and duplicated diagnostic information
	modified:   compiler/rustc_typeck/src/check/coercion.rs
	new file:   src/test/ui/typeck/issue-100285.rs
	new file:   src/test/ui/typeck/issue-100285.stderr

…ut, r=wesleywiser

Add support for generating unique profraw files by default when using `-C instrument-coverage`

Currently, enabling the rustc flag `-C instrument-coverage` instruments the given crate and by default uses the naming scheme `default.profraw` for any instrumented profile files generated during the execution of a binary linked against this crate. This leads to multiple binaries being executed overwriting one another and causing only the last executable run to contain actual coverage results.

This can be overridden by manually setting the environment variable `LLVM_PROFILE_FILE` to use a unique naming scheme.

This PR adds a change to add support for a reasonable default for rustc to use when enabling coverage instrumentation similar to how the Rust compiler treats generating these same `profraw` files when PGO is enabled.

The new naming scheme is set to `default_%m_%p.profraw` to ensure the uniqueness of each file being generated using [LLVMs special pattern strings](https://clang.llvm.org/docs/SourceBasedCodeCoverage.html#running-the-instrumented-program).

Today the compiler sets the default for PGO `profraw` files to `default_%m.profraw` to ensure a unique file for each run. The same can be done for the instrumented profile files generated via the `-C instrument-coverage` flag as well which LLVM has API support for.

Linked Issue: rust-lang#100381

r? `@wesleywiser`

Update the minimum external LLVM to 13

With this change, we'll have stable support for LLVM 13 through 15 (pending release).
For reference, the previous increase to LLVM 12 was rust-lang#90175.

r? `@nagisa`

Add missing closing quote

fixes rust-lang#100563

…h, r=compiler-errors

Suggest adding an array length if possible

fixes rust-lang#100448

…lfJung

Rename Machine memory hooks to suggest when they run

Some of the other memory hooks start with `before_` or `after_` to indicate that they run before or after a certain operation. These don't, so I was a bit confused as to when they are supposed to run.

`memory_read` can be read two ways in English, "memory was read" or "this is a memory read" so without the prefix this was especially ambiguous.