Fix #2530: ArgumentOutOfRangeException in PatternMatchRefTypes

siegfriedpammer · siegfriedpammer · commit 22c98016a97b · 2021-11-06T13:08:45.000+01:00
diff --git a/ICSharpCode.Decompiler/IL/Transforms/PatternMatchingTransform.cs b/ICSharpCode.Decompiler/IL/Transforms/PatternMatchingTransform.cs
@@ -132,7 +132,7 @@ private bool PatternMatchRefTypes(Block block, BlockContainer container, ILTrans
 			{
 				// stloc v(ldloc s)
 				pos--;
-				if (!block.Instructions[pos].MatchStLoc(s, out value))
+				if (pos < 0 || !block.Instructions[pos].MatchStLoc(s, out value))
 					return false;
 				if (v.Kind is not (VariableKind.Local or VariableKind.StackSlot))
 					return false;

Original file line number	Diff line number	Diff line change
`@@ -132,7 +132,7 @@ private bool PatternMatchRefTypes(Block block, BlockContainer container, ILTrans`
`132`	`132`	`{`
`133`	`133`	`// stloc v(ldloc s)`
`134`	`134`	`pos--;`
`135`		`- if (!block.Instructions[pos].MatchStLoc(s, out value))`
	`135`	`+ if (pos < 0 \|\| !block.Instructions[pos].MatchStLoc(s, out value))`
`136`	`136`	`return false;`
`137`	`137`	`if (v.Kind is not (VariableKind.Local or VariableKind.StackSlot))`
`138`	`138`	`return false;`