PCL: Add some semantically erroroneous programs

pcl/programs-erroneous/semantic_error_16.pcl

@@ -0,0 +1,14 @@
+program sem_error_illegal_cross_scope_jump;
+(* Error: Illegal cross-scope jump: label declared in the main block but used by goto inside a nested procedure *)
+
+label outside;
+
+procedure inner();
+begin
+    goto outside
+end;
+
+begin
+    inner();
+    outside : writeString("outside")
+end.

pcl/programs-erroneous/semantic_error_17.pcl

@@ -0,0 +1,9 @@
+program sem_error_goto_label_not_defined;
+(* Error: 'goto' targets a label that is declared but never defined in any body *)
+
+label missing;
+
+begin
+    goto missing;
+    writeString("error")
+end.

pcl/programs-erroneous/semantic_error_18.pcl

@@ -0,0 +1,11 @@
+program sem_error_result_in_procedure;
+(* Error: 'result' is used inside a procedure (procedures do not return values) *)
+
+procedure p();
+begin
+    result := 1
+end;
+
+begin
+    p()
+end.

pcl/programs-erroneous/semantic_error_19.pcl

@@ -0,0 +1,6 @@
+program sem_error_result_in_main;
+(* Error: 'result' is used in the main program body (result exists only inside functions) *)
+
+begin
+    result := 1
+end.

pcl/programs-erroneous/semantic_error_20.pcl

@@ -0,0 +1,13 @@
+program sem_error_forward_function_mismatch;
+(* Error: Forward function declaration is not consistent with the later definition *)
+
+forward function foo(x : integer) : integer;
+
+function foo(x : integer; y : integer) : integer;
+begin
+    result := x + y
+end;
+
+begin
+    writeString("error")
+end.

pcl/programs-erroneous/semantic_error_21.pcl

@@ -0,0 +1,13 @@
+program sem_error_assignment_from_procedure_call;
+(* Error: No assignment from procedure calls (only functions can return values) *)
+
+var x : integer;
+
+procedure p();
+begin
+    writeString("hello")
+end;
+
+begin
+    x := p()
+end.

pcl/programs-erroneous/semantic_error_22.pcl

@@ -0,0 +1,5 @@
+program sem_error_deref_nil;
+(* Error: Dereferencing nil *)
+begin
+    writeInteger(nil^)
+end.

pcl/programs-erroneous/semantic_error_23.pcl

@@ -0,0 +1,11 @@
+program sem_error_var_param_requires_lvalue_const;
+(* Error: 'var' (by reference) parameter requires an lvalue; constant passed *)
+
+procedure inc(var x : integer);
+begin
+    x := x + 1
+end;
+
+begin
+    inc(1)
+end.

pcl/programs-erroneous/semantic_error_24.pcl

@@ -0,0 +1,14 @@
+program sem_error_var_param_requires_lvalue_expr;
+(* Error: 'var' (by reference) parameter requires an lvalue; expression passed *)
+
+var a : integer;
+
+procedure inc(var x : integer);
+begin
+    x := x + 1
+end;
+
+begin
+    a := 10;
+    inc(a + 1)
+end.