Merge pull request #22671 from owen-mc/go/fix/go-panic-abrupt-completion

Go: fix CFG bug - no control flow beyond `go panic()`

Author: owen-mc

go/ql/lib/semmle/go/controlflow/ControlFlowGraphImpl.qll

@@ -664,6 +664,9 @@ module CfgImpl {
     /** Helper: blank identifier check */
     private predicate notBlankIdent(Go::Expr e) { not e instanceof Go::BlankIdent }
 
+    /** Holds if `e` is invoked in a newly started goroutine. */
+    private predicate isGoStmtCall(Ast::AstNode e) { e = any(Go::GoStmt s).getCall() }
+
     /** Helper: implicit field selection for promoted selectors */
     additional predicate implicitFieldSelection(Ast::AstNode e, int index, Go::Field implicitField) {
       exists(Go::StructType baseType, Go::PromotedField child, int implicitFieldDepth |
@@ -704,6 +707,7 @@ module CfgImpl {
       Ast::AstNode ast, PreControlFlowNode n, AbruptCompletion c, boolean always
     ) {
       ast instanceof Go::CallExpr and
+      not isGoStmtCall(ast) and
       (
         not exists(ast.(Go::CallExpr).getTarget()) or
         ast.(Go::CallExpr).getTarget().mayPanic()
@@ -727,6 +731,7 @@ module CfgImpl {
       // exception completion so that the shared library's default In->After step
       // is suppressed.
       ast instanceof Go::CallExpr and
+      not isGoStmtCall(ast) and
       exists(Go::Function target | target = ast.(Go::CallExpr).getTarget() |
         target.mustPanic() or target.mustNotReturnNormally()
       ) and
@@ -848,6 +853,7 @@ module CfgImpl {
     private predicate mayPanic(Ast::AstNode ast) {
       ast instanceof Go::CallExpr and
       not ast = any(Go::DeferStmt s).getCall() and
+      not isGoStmtCall(ast) and
       (not exists(ast.(Go::CallExpr).getTarget()) or ast.(Go::CallExpr).getTarget().mayPanic()) and
       not exists(Go::Function target | target = ast.(Go::CallExpr).getTarget() |
         target.mustNotReturnNormally() and not target.mustPanic()

go/ql/test/library-tests/semmle/go/controlflow/ControlFlowGraph/ControlFlowNode_getASuccessor.expected

@@ -3127,7 +3127,6 @@
 | stmts.go:135:3:135:14 | expression statement | stmts.go:135:3:135:14 | Before call to test5 |
 | stmts.go:135:9:135:13 | false | stmts.go:135:3:135:14 | call to test5 |
 | stmts.go:140:1:142:1 | Entry | stmts.go:140:13:140:13 | f |
-| stmts.go:140:1:142:1 | Exceptional Exit | stmts.go:140:1:142:1 | Exit |
 | stmts.go:140:1:142:1 | Normal Exit | stmts.go:140:1:142:1 | Exit |
 | stmts.go:140:1:142:1 | function declaration | stmts.go:145:1:159:1 | function declaration |
 | stmts.go:140:13:140:13 | f | stmts.go:140:23:142:1 | block statement |
@@ -3139,7 +3138,6 @@
 | stmts.go:141:5:141:5 | f | stmts.go:141:5:141:7 | call to f |
 | stmts.go:141:5:141:7 | After call to f | stmts.go:141:2:141:7 | go statement |
 | stmts.go:141:5:141:7 | Before call to f | stmts.go:141:5:141:5 | f |
-| stmts.go:141:5:141:7 | call to f | stmts.go:140:1:142:1 | Exceptional Exit |
 | stmts.go:141:5:141:7 | call to f | stmts.go:141:5:141:7 | After call to f |
 | stmts.go:145:1:159:1 | Entry | stmts.go:145:13:145:14 | xs |
 | stmts.go:145:1:159:1 | Exceptional Exit | stmts.go:145:1:159:1 | Exit |

go/ql/test/query-tests/RedundantCode/UnreachableStatement/CONSISTENCY/CfgConsistency.expected

@@ -1,5 +1,5 @@
 consistencyOverview
-| deadEnd | 9 |
+| deadEnd | 10 |
 deadEnd
 | main.go:17:2:17:10 | select statement |
 | main.go:109:2:109:10 | select statement |
@@ -10,3 +10,4 @@ deadEnd
 | main.go:145:2:145:10 | select statement |
 | main.go:151:2:151:10 | select statement |
 | main.go:157:2:157:10 | select statement |
+| main.go:164:2:164:10 | select statement |

go/ql/test/query-tests/RedundantCode/UnreachableStatement/main.go

@@ -159,4 +159,9 @@ func test19() mystruct {
 	return mystruct{test10(1), test10(2) == 2} // $ Alert
 }
 
+func test20() {
+	go panic("panic in another goroutine")
+	select {} // OK: reachable after starting the goroutine
+}
+
 func main() {}