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physx-sys: Emit default values in FFI bindings for literal values #221

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physx-sys: Emit default values in FFI bindings for literal values #221

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dcdc1a3
physx-sys: Emit default values in FFI bindings for literal values
mgustavsson Oct 31, 2023
0625650
FFI default values: nicer float formatting
slvmnd Nov 15, 2023
90ec3f0
Merge branch 'main' into default_values
slvmnd Nov 15, 2023
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27 changes: 26 additions & 1 deletion physx-sys/pxbind/src/consumer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,31 @@ pub enum Item {
kind: Type,
},
ConstantExpr {
value: Option<String>,
#[serde(rename = "type")]
kind: Type,
},
CXXBoolLiteralExpr {
value: bool,
#[serde(rename = "type")]
kind: Type,
},
IntegerLiteral {
value: String,
#[serde(rename = "type")]
kind: Type,
},
FloatingLiteral {
value: String,
#[serde(rename = "type")]
kind: Type,
},
StringLiteral {
value: String,
#[serde(rename = "type")]
kind: Type,
},
UserDefinedLiteral {
value: String,
#[serde(rename = "type")]
kind: Type,
Expand All @@ -111,7 +136,7 @@ pub enum Item {
TemplateArgument {
#[serde(rename = "type")]
kind: Option<Type>,
value: Option<i32>,
value: Option<i64>,
},
RecordType {
#[serde(rename = "type")]
Expand Down
4 changes: 3 additions & 1 deletion physx-sys/pxbind/src/consumer/enums.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -110,7 +110,9 @@ impl<'ast> super::AstConsumer<'ast> {
}
}

return value.parse().context("failed to parse enum constant");
if let Some(v) = value {
return v.parse().context("failed to parse enum constant");
}
}
_ => continue,
}
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29 changes: 26 additions & 3 deletions physx-sys/pxbind/src/consumer/functions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ pub struct Function {
pub struct Param<'ast> {
pub name: Cow<'ast, str>,
pub kind: QualType<'ast>,
pub default_value: Option<&'ast str>,
}

impl<'ast> Param<'ast> {
Expand All @@ -27,6 +28,7 @@ impl<'ast> Param<'ast> {
is_pointee_const: is_const,
pointee: Box::new(rec_type),
},
default_value: None,
}
}
}
Expand Down Expand Up @@ -181,12 +183,29 @@ impl<'ast> super::AstConsumer<'ast> {
template_types: &[(&str, &TemplateArg<'ast>)],
func: &mut FuncBinding<'ast>,
) -> anyhow::Result<()> {
for (i, param) in node
for (i, (param, default_value)) in node
.inner
.iter()
.filter_map(|inn| {
if let Item::ParmVarDecl(param) = &inn.kind {
Some(param)
if inn.inner.len() > 0 {
let default_value: Option<&str> = match &inn.inner[0].kind {
Item::IntegerLiteral { value, kind: _ } => Some(value),
Item::FloatingLiteral { value, kind: _ } => {
Some(if value == "1.00999999" { "1.01" } else { value })
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This seems... weird to me. I don't think you could get a floating point error turning 1.01 into 1.0099999. Where does it show up?

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In the C++ headers the "inflation" parameter to several different functions often has the value of "1.01" - but the Clang++ json dump command prints these values as 1.00999999 - so changing it back to 1.01 better matches the original value in the C++ headers.

virtual		PxBounds3		getWorldBounds(float inflation = 1.01f) const = 0;

A more general fix would obviously be to handle any floating point value that seems to have been incorrectly formatted, but I think this was basically the only default value PhysX uses that has this error.

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@slvmnd slvmnd Oct 31, 2023 •
edited
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Putting:

float f(float a=1.01f) {
	return a+a;
}

Through "clang++ -Xclang -ast-dump=json -fsyntax-only tst.cpp" gives:

          "name": "a",
          "type": {
            "qualType": "float"
          },
          "init": "c",
          "inner": [
            {
              "id": "0x7fe26608a580",
              "kind": "FloatingLiteral",
              "range": {
                "begin": {
                  "offset": 14,
                  "col": 15,
                  "tokLen": 5
                },
                "end": {
                  "offset": 14,
                  "col": 15,
                  "tokLen": 5
                }
              },
              "type": {
                "qualType": "float"
              },
              "valueCategory": "prvalue",
              "value": "1.00999999"
            }
          ]

🥴

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It's the same value in f32, clang just does lazy job at human-formatting:

dbg!(1.01f32-1.00999999f32 == 0.0f32);
dbg!(1.01f32-1.00999999f32);
dbg!(1.01f64-1.00999999f64 == 0.0f64);
dbg!(1.01f64-1.00999999f64);
[src\main.rs:2] 1.01f32 - 1.00999999f32 == 0.0f32 = true
[src\main.rs:3] 1.01f32 - 1.00999999f32 = 0.0
[src\main.rs:4] 1.01f64 - 1.00999999f64 == 0.0f64 = false
[src\main.rs:5] 1.01f64 - 1.00999999f64 = 9.99999993922529e-9

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I would suggest to parse and format it back in rust (and add a comment explaining it):

value.parse::<f32>().ok().map(|value| format!("{value}"))
[src\main.rs:2] "1.00999999".parse::<f32>().ok().map(|value| format!("{value}")) = Some(
    "1.01",
)

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Thanks for the suggestion @rlidwka - I have updated the pull request using format! instead.

}
Item::StringLiteral { value, kind: _ } => Some(value),
Item::UserDefinedLiteral { value, kind: _ } => Some(value),
Item::CXXBoolLiteralExpr { value, kind: _ } => {
Some(if *value { "true" } else { "false" })
}
_ => None,
};

Some((param, default_value))
} else {
Some((param, None))
}
} else {
None
}
Expand All @@ -206,7 +225,11 @@ impl<'ast> super::AstConsumer<'ast> {
)
})?;

func.params.push(Param { name: pname, kind });
func.params.push(Param {
name: pname,
kind,
default_value: default_value,
});
}

Ok(())
Expand Down
14 changes: 13 additions & 1 deletion physx-sys/pxbind/src/generator/functions.rs
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Expand Up @@ -190,8 +190,20 @@ impl<'ast> FuncBinding<'ast> {
}

let indent = Indent(level);

let mut acc = String::new();

// write default values of params
let mut first_param = true;
for param in self.params.iter() {
if let Some(v) = &param.default_value {
if first_param {
writesln!(acc, "{indent}///");
first_param = false;
}
writesln!(acc, "{indent}/// {} = {}", param.name, v);
}
}

writes!(acc, "{indent}pub fn {}(", self.name);

for (i, param) in self.params.iter().enumerate() {
Expand Down