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compiler: Fix expression switch with non-last default #4078

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compiler: Fix expression switch with non-last default #4078

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8 changes: 8 additions & 0 deletions pkg/compiler/codegen.go
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Original file line number Diff line number Diff line change
Expand Up @@ -878,6 +878,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
c.currentSwitch = label
c.pushStackLabel(label, 1)

last := len(n.Body.List) - 1
for i := range last {
if n.Body.List[i].(*ast.CaseClause).List == nil { // early default
n.Body.List[i], n.Body.List[last] = n.Body.List[last], n.Body.List[i]
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@AnnaShaleva AnnaShaleva Dec 3, 2025

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We need to check if this substitution affects generated debug info. Lines info stored in debug info for substituted default should match the source code.

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@cthulhu-rider cthulhu-rider Dec 3, 2025

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how can i check this?

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@AnnaShaleva AnnaShaleva Dec 4, 2025

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See how saveSequencePoint works, ensure that proper statement boundaries will be stored in the debug info file on compilation:

neo-go/pkg/compiler/debug.go

Line 128 in 93fe450

func (c *codegen) saveSequencePoint(n ast.Node) {

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@AnnaShaleva AnnaShaleva Dec 11, 2025

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@cthulhu-rider ping.

break
}
}

startLabels := make([]uint16, len(n.Body.List))
for i := range startLabels {
startLabels[i] = c.newLabel()
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40 changes: 40 additions & 0 deletions pkg/compiler/switch_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,46 @@ var switchTestCases = []testCase{
`,
big.NewInt(1),
},
{
"case after first default",
`func F%d() int {
a := 5
switch a {
default: return 4
case 5: return 2
}
}
`,
big.NewInt(2),
},
{
"case after intermediate default",
`func F%d() int {
a := 6
switch a {
case 5: return 2
default: return 4
case 6:
}
return 1
}
`,
big.NewInt(1),
},
{
"intermediate default",
`func F%d() int {
a := 3
switch a {
case 5: return 2
default: return 4
case 6:
}
return 1
}
`,
big.NewInt(4),
},
{
"expression in case clause",
`func F%d() int {
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