Dead code analysis with labelled if did not work properly.

releasenotes.md

@@ -45,6 +45,7 @@
 - Fix several issues relating to multi-level inference like `int[*][*]` #2505
 - `$for int $a = 1; $a < 2; $a++` would not parse.
 - Fix lambda-in-macro visibility, where lambdas would sometimes not correctly link if used through a macro.
+- Dead code analysis with labelled `if` did not work properly.
 
 ### Stdlib changes
 - Added generic `InterfaceList` to store a list of values that implement a specific interface

src/compiler/sema_stmts.c

@@ -1989,20 +1989,23 @@ static inline bool sema_analyse_if_stmt(SemaContext *context, Ast *statement)
 		SCOPE_START_WITH_LABEL(statement->if_stmt.flow.label);
 			if (result == COND_FALSE) context->active_scope.is_dead = true;
 			success = success && sema_analyse_statement(context, then);
-			then_jump = context->active_scope.end_jump.active;
+			then_jump = context->active_scope.end_jump.active && !(statement->if_stmt.flow.label && statement->if_stmt.flow.has_break);
 		SCOPE_END;
 
 		if (!success) goto END;
 		else_jump = false;
 		if (statement->if_stmt.else_body)
 		{
+			bool store_break = statement->if_stmt.flow.has_break;
+			statement->if_stmt.flow.has_break = false;
 			SCOPE_START_WITH_LABEL(statement->if_stmt.flow.label);
 				if (result == COND_TRUE) context->active_scope.is_dead = true;
 				sema_remove_unwraps_from_try(context, cond);
 				sema_unwrappable_from_catch_in_else(context, cond);
 				success = success && sema_analyse_statement(context, else_body);
-				else_jump = context->active_scope.end_jump.active;
+				else_jump = context->active_scope.end_jump.active && !(statement->if_stmt.flow.label && statement->if_stmt.flow.has_break);
 			SCOPE_END;
+			statement->if_stmt.flow.has_break |= store_break;
 		}
 
 END:
@@ -2022,6 +2025,7 @@ END:
 	}
 	if (then_jump && else_jump && !statement->flow.has_break)
 	{
+
 		SET_JUMP_END(context, statement);
 	}
 	else if (then_jump && result == COND_TRUE)

test/test_suite/statements/foreach_with_only_ref.c3t

@@ -1,3 +1,4 @@
+// #target: macos-x64
 module test;
 import std;
 

test/test_suite/statements/if_break.c3t

@@ -0,0 +1,81 @@
+// #target: macos-x64
+module test;
+int a;
+fn void test()
+{
+
+    if LABEL: (false)
+    {
+        a += 1;
+    }
+    else if (true)
+    {
+        a += 2;
+        break LABEL;
+    }
+    else
+    {
+        a += 3;
+    }
+
+	a *= 4;
+}
+
+fn void main()
+{
+    if LABEL: (true)
+    {
+        a += 1;
+        break LABEL;
+    }
+    else if (true)
+    {
+        a += 2;
+    }
+    else
+    {
+        a += 3;
+    }
+
+	a *= 4;
+}
+
+/* #expect: test.ll
+
+define void @test.test() #0 {
+entry:
+  br label %if.else
+
+if.else:                                          ; preds = %entry
+  br label %if.then
+
+if.then:                                          ; preds = %if.else
+  %0 = load i32, ptr @test.a, align 4
+  %add = add i32 %0, 2
+  store i32 %add, ptr @test.a, align 4
+  br label %if.exit
+
+if.exit:                                          ; preds = %if.then
+  %1 = load i32, ptr @test.a, align 4
+  %mul = mul i32 %1, 4
+  store i32 %mul, ptr @test.a, align 4
+  ret void
+}
+
+; Function Attrs: nounwind uwtable
+define void @test.main() #0 {
+entry:
+  br label %if.then
+
+if.then:                                          ; preds = %entry
+  %0 = load i32, ptr @test.a, align 4
+  %add = add i32 %0, 1
+  store i32 %add, ptr @test.a, align 4
+  br label %if.exit
+
+if.exit:                                          ; preds = %if.then
+  %1 = load i32, ptr @test.a, align 4
+  %mul = mul i32 %1, 4
+  store i32 %mul, ptr @test.a, align 4
+  ret void
+}