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Include implicit type switch var in CFG

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This commit is contained in:
Owen Mansel-Chan
2026-06-03 16:56:25 +01:00
parent 0f6bccf208
commit 3cd6a279d0
1 changed files with 40 additions and 4 deletions
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44
go/ql/lib/semmle/go/controlflow/ControlFlowGraphShared.qll
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@@ -1320,6 +1320,21 @@ module GoCfg {
)
}
/**
* Holds if `cc` is a case clause of a type switch with an assignment that
* implicitly declares a variable whose type narrows to the case type. In
* this situation the CFG inserts a `type-switch-var` additional node
* between the case test and the case body, on which the IR layer
* materialises the implicit assignment to that variable.
*/
private predicate hasTypeSwitchVar(Go::CaseClause cc) {
exists(Go::TypeSwitchStmt ts |
ts.getACase() = cc and
exists(ts.getAssign()) and
exists(cc.getImplicitlyDeclaredVariable())
)
}
private predicate caseClause(PreControlFlowNode n1, PreControlFlowNode n2) {
exists(Go::SwitchStmt sw, Go::CaseClause cc, int i | cc = sw.getNonDefaultCase(i) |
n1.isBefore(cc) and n2.isBefore(cc.getExpr(0))
@@ -1334,9 +1349,14 @@ module GoCfg {
exists(int last | last = max(int j | exists(cc.getExpr(j))) |
afterCaseExprMatch(sw, cc.getExpr(last), n1) and
(
n2.isBefore(cc.getStmt(0))
hasTypeSwitchVar(cc) and n2.isAdditional(cc, "type-switch-var")
or
not exists(cc.getStmt(0)) and n2.isAfter(sw)
not hasTypeSwitchVar(cc) and
(
n2.isBefore(cc.getStmt(0))
or
not exists(cc.getStmt(0)) and n2.isAfter(sw)
)
)
or
afterCaseExprNoMatch(sw, cc.getExpr(last), n1) and
@@ -1355,9 +1375,25 @@ module GoCfg {
exists(Go::SwitchStmt sw, Go::CaseClause def | def = sw.getDefault() |
n1.isBefore(def) and
(
n2.isBefore(def.getStmt(0))
hasTypeSwitchVar(def) and n2.isAdditional(def, "type-switch-var")
or
not exists(def.getStmt(0)) and n2.isAfter(sw)
not hasTypeSwitchVar(def) and
(
n2.isBefore(def.getStmt(0))
or
not exists(def.getStmt(0)) and n2.isAfter(sw)
)
)
)
or
exists(Go::SwitchStmt sw, Go::CaseClause cc |
sw.getACase() = cc and
hasTypeSwitchVar(cc) and
n1.isAdditional(cc, "type-switch-var") and
(
n2.isBefore(cc.getStmt(0))
or
not exists(cc.getStmt(0)) and n2.isAfter(sw)
)
)
or