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b64f549ba9
Added a debug flag "-d closure" to explain compilation of closures (should this be done some other way? Should we rewrite the "-m" flag to "-d escapes"?) Used this to discover that cause was an OXXX node in the captured vars list, and in turn noticed that OXXX nodes are explicitly ignored in all other processing of captured variables. Couldn't figure out a reproducer, did verify that this OXXX was not caused by an unnamed return value (which is one use of these). Verified lack of heap allocation by examining -S output. Assembly: (runtime/mgc.go:1371) PCDATA $0, $2 (runtime/mgc.go:1371) CALL "".notewakeup(SB) (runtime/mgc.go:1377) LEAQ "".gcBgMarkWorker.func1·f(SB), AX (runtime/mgc.go:1404) MOVQ AX, (SP) (runtime/mgc.go:1404) MOVQ "".autotmp_2242+88(SP), CX (runtime/mgc.go:1404) MOVQ CX, 8(SP) (runtime/mgc.go:1404) LEAQ go.string."GC worker (idle)"(SB), AX (runtime/mgc.go:1404) MOVQ AX, 16(SP) (runtime/mgc.go:1404) MOVQ $16, 24(SP) (runtime/mgc.go:1404) MOVB $20, 32(SP) (runtime/mgc.go:1404) MOVQ $0, 40(SP) (runtime/mgc.go:1404) PCDATA $0, $2 (runtime/mgc.go:1404) CALL "".gopark(SB) Added a check for compiling_runtime to ensure that this is caught in the future. Added a test to test the check. Verified that 1.5.3 did NOT reject the test case when compiled with -+ flag, so this is not a recently added bug. Cause of bug is two-part -- there was no leaking closure detection ever, and instead it relied on capture-of-variables to trigger compiling_runtime test, but closures improved in 1.5.3 so that mere capture of a value did not also capture the variable, which thus allowed closures to escape, as well as this case where the escape was spurious. In fixedbugs/issue14999.go, compare messages for f and g; 1.5.3 would reject g, but not f. 1.4 rejects both because 1.4 heap-allocates parameter x for both. Fixes #14999. Change-Id: I40bcdd27056810628e96763a44f2acddd503aee1 Reviewed-on: https://go-review.googlesource.com/21322 Run-TryBot: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
19 lines
521 B
Go
19 lines
521 B
Go
// errorcheck -+
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package p
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func f(x int) func(int) int {
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return func(y int) int { return x + y } // ERROR "heap-allocated closure, not allowed in runtime."
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}
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func g(x int) func(int) int { // ERROR "x escapes to heap, not allowed in runtime."
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return func(y int) int { // ERROR "heap-allocated closure, not allowed in runtime."
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x += y
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return x + y
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}
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}
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