From 810c37ec1e0fa218979ca8b0cc72db68b477cfb9 Mon Sep 17 00:00:00 2001
From: Ellen Arteca <emarteca@google.com>
Date: Tue, 23 Apr 2024 00:17:47 +0000
Subject: [PATCH] Adds support to bindgen to handle static inline fcts

Adds support for bindgen to be able to handle `static inline`
functions. This is done by adding a new boolean field to the `BindgenProperties`
struct, `Handle_static_inline` (default to false).
If this field is true, then the flags to trigger bindgen support of
static inline functions are passed in.

The rust-bindgen documentation list two ways of handling `static inline`
functions, both specified with command line args.
1) --generate-inline-functions
2) --experimental --wrap-static-fns

Option 1 requires some extra effort on the part of the C library developer, in
that they have to expose the function symbols: the docs (linked below) explain
that this is often done by compiling the library with inlining disabled, which
can be detrimental to performance.

Option 2 requires no effort on the part of the C library developer, but it does
require the `--experimental` flag, since this feature is still under development.

This CL goes with option 2.

Relevant docs: https://github.com/rust-lang/rust-bindgen/discussions/2405

This CL also adds a new test: TestBindgenHandleStaticInlining in bindgen_test.go

Test: m blueprint_tests
Change-Id: If28000e3f3ccecc65c4cae1c62d7bf455454239a
---
 rust/bindgen.go      |  6 ++++++
 rust/bindgen_test.go | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/rust/bindgen.go b/rust/bindgen.go
index 11ba74d45..eaed1b9d4 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -101,6 +101,9 @@ type BindgenProperties struct {
 	//
 	// "my_bindgen [flags] wrapper_header.h -o [output_path] -- [clang flags]"
 	Custom_bindgen string
+
+	// flag to indicate if bindgen should handle `static inline` functions (default is false)
+	Handle_static_inline bool
 }
 
 type bindgenDecorator struct {
@@ -232,6 +235,9 @@ func (b *bindgenDecorator) GenerateSource(ctx ModuleContext, deps PathDeps) andr
 
 	bindgenFlags := defaultBindgenFlags
 	bindgenFlags = append(bindgenFlags, esc(b.Properties.Bindgen_flags)...)
+	if b.Properties.Handle_static_inline {
+		bindgenFlags = append(bindgenFlags, "--experimental --wrap-static-fns")
+	}
 
 	// cat reads from stdin if its command line is empty,
 	// so we pass in /dev/null if there are no other flag files
diff --git a/rust/bindgen_test.go b/rust/bindgen_test.go
index 0c0a6dad0..11cfe4e88 100644
--- a/rust/bindgen_test.go
+++ b/rust/bindgen_test.go
@@ -227,3 +227,22 @@ func TestBindgenFlagFile(t *testing.T) {
 	// TODO: The best we can do right now is check $flagfiles. Once bindgen.go switches to RuleBuilder,
 	// we may be able to check libbinder.RuleParams.Command to see if it contains $(cat /dev/null flag_file.txt)
 }
+
+
+func TestBindgenHandleStaticInlining(t *testing.T) {
+	ctx := testRust(t, `
+		rust_bindgen {
+			name: "libbindgen",
+			wrapper_src: "src/any.h",
+			crate_name: "bindgen",
+			stem: "libbindgen",
+			source_stem: "bindings",
+			handle_static_inline: true
+		}
+	`)
+	libbindgen := ctx.ModuleForTests("libbindgen", "android_arm64_armv8-a_source").Output("bindings.rs")
+	// Make sure the flag to support `static inline` functions is present
+	if !strings.Contains(libbindgen.Args["flags"], "--wrap-static-fns") {
+		t.Errorf("missing flag to handle static inlining in rust_bindgen rule: flags %#v", libbindgen.Args["flags"])
+	}
+}