Improve and collate diagnostics for uses of unsafe constructs in declarations #78307
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DougGregor
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@swift-ci please smoke test |
For now, just use this as an intermediate state to provide a single place to render diagnostics.
Instead of producing a warning for each use of an unsafe entity, collect all of the uses of unsafe constructs within a given function and batch them together in a single diagnostic at the function level that tells you what you can do (add `@unsafe` or `@safe(unchecked)`, depending on whether all unsafe uses were in the definition), plus notes identifying every unsafe use within that declaration. The new diagnostic renderer nicely collects together in a single snippet, so it's easier to reason about. Here's an example from the embedded runtime that previously would have been 6 separate warnings, each with 1-2 notes: ``` swift/stdlib/public/core/EmbeddedRuntime.swift:397:13: warning: global function 'swift_retainCount' involves unsafe code; use '@safe(unchecked)' to assert that the code is memory-safe 395 | 396 | @_cdecl("swift_retainCount") 397 | public func swift_retainCount(object: Builtin.RawPointer) -> Int { | `- warning: global function 'swift_retainCount' involves unsafe code; use '@safe(unchecked)' to assert that the code is memory-safe 398 | if !isValidPointerForNativeRetain(object: object) { return 0 } 399 | let o = UnsafeMutablePointer<HeapObject>(object) | | `- note: call to unsafe initializer 'init(_:)' | `- note: reference to unsafe generic struct 'UnsafeMutablePointer' 400 | let refcount = refcountPointer(for: o) | | `- note: reference to let 'o' involves unsafe type 'UnsafeMutablePointer<HeapObject>' | `- note: call to global function 'refcountPointer(for:)' involves unsafe type 'UnsafeMutablePointer<Int>' 401 | return loadAcquire(refcount) & HeapObject.refcountMask | | `- note: reference to let 'refcount' involves unsafe type 'UnsafeMutablePointer<Int>' | `- note: call to global function 'loadAcquire' involves unsafe type 'UnsafeMutablePointer<Int>' 402 | } 403 | ``` Note that we have lost a little bit of information, because we no longer produce "unsafe declaration was here" notes pointing back at things like `UnsafeMutablePointer` or `recountPointer(for:)`. However, strict memory safety tends to be noisy to turn on, so it's worth losing a little bit of easily-recovered information to gain some brevity.
…n handle it Drive the strict-safety diagnostics for a particular declaration from primary type checking for declarations, so any memory-safety-related diagnostics will only be emitted for the primary files. This also brings them together as notes under a single warning for each declaration.
…currency code A nonisolated(unsafe) declaration clearly indicates that the declaration itself is unsafe, so it doesn't need to be diagnosted. Instead, diagnose any reference to such a declaration that occurs when strict concurrency is enabled. Make this a collatable unsafe use.
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Instead of producing a warning for each use of an unsafe entity, collect all of the uses of unsafe constructs within a given function and batch them together in a single diagnostic at the enclosing declaration that tells you what you can do (add
@unsafeor@safe(unchecked), depending on whether all unsafe uses were in the definition), plus notes identifying every unsafe use within that declaration. The new diagnostic renderer nicely collects together in a single snippet, so it's easier to reason about.Here's an example from the embedded runtime that previously would have been 6 separate warnings, each with 1-2 notes:
Note that we have lost a little bit of information, because we no longer produce "unsafe declaration was here" notes pointing back at things like
UnsafeMutablePointerorrecountPointer(for:). However, strict memory safety tends to be noisy to turn on, so it's worth losing a little bit of easily-recovered information to gain some brevity.While here, also fix a few issues with the checking:
nonisolated(unsafe)declarations, not the declaration itselfunowned(unsafe)declarations, not the declaration itself