[ASTGen] Fix off-by-one error in allocation of UTF-8 string for buffer use

DougGregor · DougGregor · commit 8461427ef4d9 · 2022-10-27T17:05:20.000-07:00
The semantics of llvm::MemoryBuffer and NULL termination are... subtle.
diff --git a/lib/ASTGen/Sources/ASTGen/Macros.swift b/lib/ASTGen/Sources/ASTGen/Macros.swift
@@ -77,7 +77,7 @@ private func allocateUTF8String(
       ptr[utf8.count] = 0
     }
 
-    return (UnsafePointer<UInt8>(ptr), capacity)
+    return (UnsafePointer<UInt8>(ptr), utf8.count)
   }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -77,7 +77,7 @@ private func allocateUTF8String(`
`77`	`77`	`ptr[utf8.count] = 0`
`78`	`78`	`}`
`79`	`79`
`80`		`- return (UnsafePointer<UInt8>(ptr), capacity)`
	`80`	`+ return (UnsafePointer<UInt8>(ptr), utf8.count)`
`81`	`81`	`}`
`82`	`82`	`}`
`83`	`83`