Syntax Error when compiling nested If statements using flow optimization

[sebw42]

Hi, I noticed that when using the flow optimization, nested if statements can cause the compiler to throw a syntax error.
Here is an example program that triggers the error:

a = 1
if True:
    if True:
        a = 2
    if True:
        a = 3
else:
    a = 4

Compiling this with ./compile.py -l program results in the following output:

Default bit length for compilation: 64
Default security parameter for compilation: 40
Compiling file Programs/Source/program.mpc
Traceback (most recent call last):
  File "MP-SPDZ/./compile.py", line 41, in <module>
    main(compiler)
  File "MP-SPDZ/./compile.py", line 36, in main
    compilation(compiler)
  File "MP-SPDZ/./compile.py", line 19, in compilation
    prog = compiler.compile_file()
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "MP-SPDZ/Compiler/compilerLib.py", line 479, in compile_file
    exec(compile(infile.read(), infile.name, "exec"), self.VARS)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/tmph9_6ft_w", line 10
    else:
    ^^^^
SyntaxError: invalid syntax

Compiling without -l or removing one of the inner if statements fixes the problem.
Thanks for looking into this!

[mkskeller]

Thank you for raising this. You should find that 94b8c33 fixes it.