add context to parsing errors in rust codegen

Summary:
Seeing thrift deserialization errors like this one is no fun:

```
deserializing `string` from Thrift binary protocol got invalid utf-8, you need to use `binary` instead: invalid utf-8 sequence of 1 bytes from index 137
```

For structures with many nested fields localizing the one field that's non-utf8
is tedious. This diff changes this error to something like:

```
Error while deserialising error field of ErrorLogEntry
Caused by:
    deserializing `string` from Thrift binary protocol got invalid utf-8, you need to use `binary` instead: invalid utf-8 sequence of 1 bytes from index 165
```

Which helps localize error a bit more.

Reviewed By: dtolnay

Differential Revision: D72914828

fbshipit-source-id: a2bc2087c1f167163c30fa2e346b6976c2aebbf1

Author: mitrandir77

Diff for: third-party/thrift/src/thrift/compiler/generate/templates/rust/lib/server_arg.mustache

@@ -44,7 +44,7 @@ impl<P: ::fbthrift::ProtocolReader> ::fbthrift::Deserialize<P> for self::Args_{{
                 ({{#field:type}}{{> lib/ttype}}{{/field:type}}, {{field:key}}) => {{!
                     }}field_{{field:name}} = ::std::option::Option::Some({{!
                     }}{{#field:has_adapter?}}{{> lib/adapter/qualified}}::from_thrift_field::<fbthrift::metadata::NoThriftAnnotations>({{/field:has_adapter?}}{{!
-                    }}{{#field:type}}{{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p)?{{!
+                    }}{{#field:type}}::anyhow::Context::context({{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p), ::fbthrift::errors::DeserializingArgError { arg: "{{field:name}}", function: "{{function:name}}"})?{{!
                     }}{{#field:has_adapter?}}, {{field:key}})?{{/field:has_adapter?}}{{!
                     }}),{{!
                 }}{{/function:args}}

Diff for: third-party/thrift/src/thrift/compiler/generate/templates/rust/lib/structimpl.mustache

@@ -176,7 +176,7 @@ where
                     }}{{^struct:all_optional?}}field_{{field:name}}{{/struct:all_optional?}}{{!
                     }} = ::std::option::Option::Some({{!
                     }}{{#field:has_adapter?}}{{> lib/adapter/qualified}}::from_thrift_field::<{{struct:rust_name}}>({{/field:has_adapter?}}{{!
-                    }}{{#field:type}}{{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p)?{{!
+                    }}{{#field:type}}::anyhow::Context::context({{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p), ::fbthrift::errors::DeserializingFieldError { field: "{{field:name}}", strct: "{{struct:name}}"})?{{!
                     }}{{#field:has_adapter?}}, {{field:key}})?{{/field:has_adapter?}}{{!
                     }}),{{!
                 }}{{/struct:fields}}

Diff for: third-party/thrift/src/thrift/compiler/generate/templates/rust/lib/unionimpl.mustache

@@ -94,7 +94,7 @@ where
                     once = true;
                     alt = ::std::option::Option::Some(Self::{{field:rust_name}}({{!
                     }}{{#field:has_adapter?}}{{> lib/adapter/qualified}}::from_thrift_field::<{{struct:rust_name}}>({{/field:has_adapter?}}{{!
-                    }}{{#field:type}}{{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p)?{{!
+                    }}{{#field:type}}::anyhow::Context::context({{#field:type_annotation?}}{{> lib/annfieldread}}{{/field:type_annotation?}}{{^field:type_annotation?}}{{> lib/read}}{{/field:type_annotation?}}{{/field:type}}(p), ::fbthrift::errors::DeserializingFieldError { field: "{{field:name}}", strct: "{{struct:name}}"})?{{!
                     }}{{#field:has_adapter?}}, {{field:key}})?{{/field:has_adapter?}}{{!
                     }}));
                 }{{!

Diff for: third-party/thrift/src/thrift/compiler/test/fixture_utils.py

@@ -309,7 +309,9 @@ def get_all_fixture_names(fixtures_root_dir_path: Path) -> list[str]:
     ```
     """
 
-    assert fixtures_root_dir_path.is_dir()
+    assert (
+        fixtures_root_dir_path.is_dir()
+    ), f"{fixtures_root_dir_path} is not a directory"
 
     fixture_dirs = (
         fixture_dir

Diff for: third-party/thrift/src/thrift/compiler/test/fixtures/adapter/out/rust/gen-rust/server.rs

@@ -115,9 +115,9 @@ impl<P: ::fbthrift::ProtocolReader> ::fbthrift::Deserialize<P> for self::Args_Se
             let (_, fty, fid) = p.read_field_begin(|_| (), ARGS)?;
             match (fty, fid as ::std::primitive::i32) {
                 (::fbthrift::TType::Stop, _) => break,
-                (::fbthrift::TType::String, 1) => field_arg1 = ::std::option::Option::Some(<crate::types::adapters::StringWithAdapter as ::fbthrift::adapter::ThriftAdapter>::from_thrift_field::<fbthrift::metadata::NoThriftAnnotations>(::fbthrift::Deserialize::read(p)?, 1)?),
-                (::fbthrift::TType::String, 2) => field_arg2 = ::std::option::Option::Some(::fbthrift::Deserialize::read(p)?),
-                (::fbthrift::TType::Struct, 3) => field_arg3 = ::std::option::Option::Some(::fbthrift::Deserialize::read(p)?),
+                (::fbthrift::TType::String, 1) => field_arg1 = ::std::option::Option::Some(<crate::types::adapters::StringWithAdapter as ::fbthrift::adapter::ThriftAdapter>::from_thrift_field::<fbthrift::metadata::NoThriftAnnotations>(::anyhow::Context::context(::fbthrift::Deserialize::read(p), ::fbthrift::errors::DeserializingArgError { arg: "arg1", function: "func"})?, 1)?),
+                (::fbthrift::TType::String, 2) => field_arg2 = ::std::option::Option::Some(::anyhow::Context::context(::fbthrift::Deserialize::read(p), ::fbthrift::errors::DeserializingArgError { arg: "arg2", function: "func"})?),
+                (::fbthrift::TType::Struct, 3) => field_arg3 = ::std::option::Option::Some(::anyhow::Context::context(::fbthrift::Deserialize::read(p), ::fbthrift::errors::DeserializingArgError { arg: "arg3", function: "func"})?),
                 (fty, _) => p.skip(fty)?,
             }
             p.read_field_end()?;
@@ -528,7 +528,7 @@ impl<P: ::fbthrift::ProtocolReader> ::fbthrift::Deserialize<P> for self::Args_Ad
             let (_, fty, fid) = p.read_field_begin(|_| (), ARGS)?;
             match (fty, fid as ::std::primitive::i32) {
                 (::fbthrift::TType::Stop, _) => break,
-                (::fbthrift::TType::Struct, 1) => field_arg = ::std::option::Option::Some(::fbthrift::Deserialize::read(p)?),
+                (::fbthrift::TType::Struct, 1) => field_arg = ::std::option::Option::Some(::anyhow::Context::context(::fbthrift::Deserialize::read(p), ::fbthrift::errors::DeserializingArgError { arg: "arg", function: "adaptedTypes"})?),
                 (fty, _) => p.skip(fty)?,
             }
             p.read_field_end()?;