5ec23663d0
The old code didn't stop after finding the fallthrough target, always
walking the entire list to the top. This would effectively break
fallthroughs, constructing an invalid graph, as the fallthrough target
would never be found.
The fix brings the loop condition in line with all the other
stack-walking loop conditions in the surrounding code, which abort
once the target block has been found.
Alternatively, the entire loop could been omitted, as 'fallthrough'
has to be the last statement in a case body and thus always refers to
the immediate element on the stack. However, since the builder already
handles malformed ASTs as gracefully as possible, it seemed better to
keep the loop and to construct a slightly less wrong graph in the
presence of malformed ASTs.
Before the fix, the following code
func fn(x int) {
for {
switch x {
case 1:
println("case 1")
fallthrough
case 2:
println("case 2")
}
}
}
would result in the following graph. Note the presence of an
undefined.branch block.
.0: # entry
succs: 1
.1: # for.body
x
1
succs: 4 6
.2: # for.done
.3: # switch.done
succs: 1
.4: # switch.body
println("case 1")
succs: 7
.5: # switch.body
println("case 2")
succs: 3
.6: # switch.next
2
succs: 5 9
.7: # undefined.branch
.8: # unreachable.branch
succs: 3
.9: # switch.next
succs: 3
After the fix, this graph is computed instead:
.0: # entry
succs: 1
.1: # for.body
x
1
succs: 4 6
.2: # for.done
.3: # switch.done
succs: 1
.4: # switch.body
println("case 1")
succs: 5
.5: # switch.body
println("case 2")
succs: 3
.6: # switch.next
2
succs: 5 8
.7: # unreachable.branch
succs: 3
.8: # switch.next
succs: 3
Change-Id: I3bb00eddec2a7da02cb929860f4c95cf477c848c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/186857
Run-TryBot: Dominik Honnef <dominik@honnef.co>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
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|---|---|---|
| benchmark/parse | ||
| blog | ||
| cmd | ||
| container/intsets | ||
| cover | ||
| go | ||
| godoc | ||
| gopls | ||
| imports | ||
| internal | ||
| playground | ||
| present | ||
| refactor | ||
| .gitattributes | ||
| .gitignore | ||
| AUTHORS | ||
| codereview.cfg | ||
| CONTRIBUTING.md | ||
| CONTRIBUTORS | ||
| go.mod | ||
| go.sum | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
Go Tools
This subrepository holds the source for various packages and tools that support the Go programming language.
Some of the tools, godoc and vet for example, are included in binary Go
distributions.
Others, including the Go guru and the test coverage tool, can be fetched with
go get.
Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.
Download/Install
The easiest way to install is to run go get -u golang.org/x/tools/.... You can
also manually git clone the repository to $GOPATH/src/golang.org/x/tools.
Report Issues / Send Patches
This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.
The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with "x/tools/(your subdir):" in the subject line, so it is easy to find.