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Java frontend: get qualified generic types of static fields #4137

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Merged
merged 3 commits into from
Feb 12, 2019
Merged

Java frontend: get qualified generic types of static fields #4137

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c7ad885
Java frontend: get qualified generic types of static fields
smowton Feb 1, 2019
a208cce
Add test for generic static field type consistency
smowton Feb 12, 2019
35213c4
Comment that static field symbols should exist
smowton Feb 12, 2019
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Binary file added jbmc/regression/jbmc/generic_static_field/Test.class
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12 changes: 12 additions & 0 deletions jbmc/regression/jbmc/generic_static_field/Test.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@

public class Test<T> {

public static Test<Integer> static_field;

public static Test<Integer> test() {

return static_field;

}

}
15 changes: 15 additions & 0 deletions jbmc/regression/jbmc/generic_static_field/test.desc
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
CORE
Test.class
--function Test.test --validate-goto-model --show-goto-functions
^EXIT=0$
^SIGNAL=0$
Test\.test:\(\)LTest;#return_value = static_field;
--
^warning: ignoring
--
This checks that the return value type matches the static field -- if it didn't,
either --validate-goto-model would throw because of a mismatching assignment, or
a cast would be used to adjust the type.

The original motivation for this test was that generic field references could
accidentally omit generic arguments that were present in function types.
16 changes: 6 additions & 10 deletions jbmc/src/java_bytecode/java_bytecode_convert_method.cpp
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Expand Up @@ -1529,12 +1529,10 @@ code_blockt java_bytecode_convert_methodt::convert_instructions(
const bool is_assertions_disabled_field=
field_name.find("$assertionsDisabled")!=std::string::npos;

const irep_idt field_id(
get_static_field(arg0.get_string(ID_class), field_name));
const symbol_exprt symbol_expr(
get_static_field(arg0.get_string(ID_class), field_name), arg0.type());

INVARIANT(
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❓ This looks like useful context for this symbol not existing that goes away by folding it into lookup_ref - do you disagree?

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Seems pointless to have an invariant that can never fail, and I think a symbol table lookup returning a reference is widely recognised as find-or-die?

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My point is "getstatic symbol should have been created before method conversion" is more useful than simply a symbol not existing. Like without that message you might (wrongly) conclude that this conversion should actually be adding to the symbol table

I'm suggesting the invariant goes about the call to lookup_ref in case that wasn't clear. Like,

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Added a clarifying comment

symbol_table.has_symbol(symbol_expr.get_identifier()),
"getstatic symbol should have been created before method conversion");
symbol_table.lookup_ref(field_id).symbol_expr());

convert_getstatic(
arg0, symbol_expr, is_assertions_disabled_field, c, results);
Expand All @@ -1549,12 +1547,10 @@ code_blockt java_bytecode_convert_methodt::convert_instructions(
PRECONDITION(op.size() == 1 && results.empty());
const auto &field_name=arg0.get_string(ID_component_name);

const irep_idt field_id(
get_static_field(arg0.get_string(ID_class), field_name));
const symbol_exprt symbol_expr(
get_static_field(arg0.get_string(ID_class), field_name), arg0.type());

INVARIANT(
symbol_table.has_symbol(symbol_expr.get_identifier()),
"putstatic symbol should have been created before method conversion");
symbol_table.lookup_ref(field_id).symbol_expr());

c = convert_putstatic(i_it->source_location, arg0, op, symbol_expr);
}
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