support redirecting subprocesses' stdout/stderr to print!() so it gets captured for rust tests

Cargo.lock

@@ -56,7 +56,7 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ad186efb764318d35165f1758e7dcef3b10628e26d41a44bc5550652e6804391"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -66,7 +66,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61a38449feb7068f52bb06c12759005cf459ee52bb4adc1d5a7c4322d716fb19"
 dependencies = [
  "anstyle",
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -218,7 +218,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a258e46cdc063eb8519c00b9fc845fc47bcfca4130e2f08e88665ceda8474245"
 dependencies = [
  "libc",
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -249,6 +249,7 @@ dependencies = [
  "hashbrown",
  "num-bigint",
  "num-traits",
+ "os_pipe",
  "serde",
  "serde_json",
  "trybuild",
@@ -334,7 +335,7 @@ version = "0.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3d1354bf6b7235cb4a0576c2619fd4ed18183f689b12b006a0ee7329eeff9a5"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -413,6 +414,16 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
+[[package]]
+name = "os_pipe"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ffd2b0a5634335b135d5728d84c5e0fd726954b87111f7506a61c502280d982"
+dependencies = [
+ "libc",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "prettyplease"
 version = "0.2.20"
@@ -457,7 +468,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -541,7 +552,7 @@ dependencies = [
  "cfg-if",
  "fastrand",
  "rustix",
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -665,14 +676,24 @@ dependencies = [
 ]
 
 [[package]]
-name = "windows-targets"
+name = "windows-sys"
-version = "0.52.4"
+version = "0.59.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7dd37b7e5ab9018759f893a1952c9420d060016fc19a472b4bb20d1bdd694d1b"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
  "windows_aarch64_gnullvm",
  "windows_aarch64_msvc",
  "windows_i686_gnu",
+ "windows_i686_gnullvm",
  "windows_i686_msvc",
  "windows_x86_64_gnu",
  "windows_x86_64_gnullvm",
@@ -681,45 +702,51 @@ dependencies = [
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bcf46cf4c365c6f2d1cc93ce535f2c8b244591df96ceee75d8e83deb70a9cac9"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "da9f259dd3bcf6990b55bffd094c4f7235817ba4ceebde8e6d11cd0c5633b675"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b474d8268f99e0995f25b9f095bc7434632601028cf86590aea5c8a5cb7801d3"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1515e9a29e5bed743cb4415a9ecf5dfca648ce85ee42e15873c3cd8610ff8e02"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5eee091590e89cc02ad514ffe3ead9eb6b660aedca2183455434b93546371a03"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77ca79f2451b49fa9e2af39f0747fe999fcda4f5e241b2898624dca97a1f2177"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.52.4"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32b752e52a2da0ddfbdbcc6fceadfeede4c939ed16d13e648833a61dfb611ed8"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "winsafe"

Cargo.toml

@@ -25,6 +25,7 @@ hashbrown = "0.14.3"
 indexmap = { version = "2.2.6", features = ["serde"] }
 num-bigint = "0.4.4"
 num-traits = "0.2.16"
+os_pipe = "1.2.1"
 prettyplease = "0.2.20"
 proc-macro2 = "1.0.83"
 quote = "1.0.36"

crates/fayalite/Cargo.toml

@@ -21,6 +21,7 @@ fayalite-proc-macros.workspace = true
 hashbrown.workspace = true
 num-bigint.workspace = true
 num-traits.workspace = true
+os_pipe.workspace = true
 serde_json.workspace = true
 serde.workspace = true
 which.workspace = true

crates/fayalite/src/cli.rs

@@ -5,6 +5,7 @@ use crate::{
     firrtl,
     intern::Interned,
     module::Module,
+    util::streaming_read_utf8::streaming_read_utf8,
 };
 use clap::{
     builder::{OsStringValueParser, TypedValueParser},
@@ -51,6 +52,8 @@ pub struct BaseArgs {
     /// the stem of the generated main output file, e.g. to get foo.v, pass --file-stem=foo
     #[arg(long)]
     pub file_stem: Option<String>,
+    #[arg(skip = false)]
+    pub redirect_output_for_rust_test: bool,
 }
 
 impl BaseArgs {
@@ -60,6 +63,34 @@ impl BaseArgs {
             top_fir_file_stem: self.file_stem.clone(),
         }
     }
+    /// handles possibly redirecting the command's output for Rust tests
+    pub fn run_external_command(
+        &self,
+        mut command: process::Command,
+    ) -> io::Result<process::ExitStatus> {
+        if self.redirect_output_for_rust_test {
+            let (reader, writer) = os_pipe::pipe()?;
+            let mut reader = io::BufReader::new(reader);
+            command.stderr(writer.try_clone()?);
+            command.stdout(writer); // must not leave writer around after spawning child
+            command.stdin(process::Stdio::null());
+            let mut child = command.spawn()?;
+            drop(command); // close writers
+            Ok(loop {
+                let status = child.try_wait()?;
+                streaming_read_utf8(&mut reader, |s| {
+                    // use print! so output goes to Rust test output capture
+                    print!("{s}");
+                    io::Result::Ok(())
+                })?;
+                if let Some(status) = status {
+                    break status;
+                }
+            })
+        } else {
+            command.status()
+        }
+    }
 }
 
 #[derive(Parser, Debug, Clone)]
@@ -188,7 +219,7 @@ impl VerilogArgs {
         }
         cmd.args(&self.firtool_extra_args);
         cmd.current_dir(&self.firrtl.base.output);
-        let status = cmd.status()?;
+        let status = self.firrtl.base.run_external_command(cmd)?;
         if status.success() {
             Ok(output)
         } else {

crates/fayalite/src/util.rs

@@ -6,6 +6,7 @@ mod const_cmp;
 mod const_usize;
 mod misc;
 mod scoped_ref;
+pub(crate) mod streaming_read_utf8;
 
 #[doc(inline)]
 pub use const_bool::{ConstBool, ConstBoolDispatch, ConstBoolDispatchTag, GenericConstBool};

crates/fayalite/src/util/streaming_read_utf8.rs

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// See Notices.txt for copyright information
+use std::{
+    io::{self, BufRead},
+    str,
+};
+
+pub(crate) fn streaming_read_utf8<R: BufRead, E: From<io::Error>>(
+    reader: R,
+    mut callback: impl FnMut(&str) -> Result<(), E>,
+) -> Result<(), E> {
+    let mut buf = [0; 4];
+    let mut buf_len = 0;
+    for byte in reader.bytes() {
+        buf[buf_len] = byte?;
+        buf_len += 1;
+        match str::from_utf8(&buf[..buf_len]) {
+            Ok(buf) => {
+                callback(buf)?;
+                buf_len = 0;
+            }
+            Err(e) => {
+                if e.error_len().is_some() {
+                    callback("\u{FFFD}")?; // replacement character
+                    buf_len = 0;
+                }
+            }
+        }
+    }
+    Ok(())
+}