Nospecialize close(c::Channel, excp::Exception) on excp. (#49508)

NHDaly · web-flow · commit a152d116bf79 · 2023-04-26T08:55:27.000-06:00
* Nospecialize close(c::Channel, excp::Exception) on excp. Fixes #49507. Avoids dynamic dispatch when closing a Channel with an Exception, and should avoid a call into the runtime for julia compilation when attempting to report an exception. * Add test for this case.
diff --git a/base/channels.jl b/base/channels.jl
@@ -183,7 +183,8 @@ Close a channel. An exception (optionally given by `excp`), is thrown by:
 * [`put!`](@ref) on a closed channel.
 * [`take!`](@ref) and [`fetch`](@ref) on an empty, closed channel.
 """
-function close(c::Channel, excp::Exception=closed_exception())
+close(c::Channel) = close(c, closed_exception()) # nospecialize on default arg seems to confuse makedocs
+function close(c::Channel, @nospecialize(excp::Exception))
     lock(c)
     try
         c.excp = excp
diff --git a/test/channels.jl b/test/channels.jl
@@ -626,3 +626,20 @@ end
         @test n_avail(c) == 0
     end
 end
+
+# Issue #49507: stackoverflow in type inference caused by close(::Channel, ::Exception)
+@testset "close(::Channel, ::StackOverflowError)" begin
+    ch = let result = Channel()
+        foo() = try
+            foo()
+        catch e;
+            close(result, e)
+        end
+
+        foo()  # This shouldn't fail with an internal stackoverflow error in inference.
+
+        result
+    end
+
+    @test (try take!(ch) catch e; e; end) isa StackOverflowError
+end
