WIP

.github/workflows/check-binary-size.yml

@@ -1,40 +1,80 @@
+# This workflow checks if a PR commit has changed the size of a hello world Rust program.
+# It downloads Rustc and compiles two versions of a stage0 compiler - one using the base commit
+# of the PR, and one using the latest commit in the PR.
+# If the size of the hello world program has changed, it posts a comment to the PR.
 name: Check binary size
 
 on:
   pull_request:
     branches:
-    - master
+      - master
 
 jobs:
   test:
     name: Check binary size
     runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
     steps:
-    - name: Print info
-      run: |
-        echo "Current SHA: ${{ github.sha }}"
-        echo "Base SHA: ${{ github.event.pull_request.base.sha }}"
-    - name: Clone Rustc
-      run: git clone https://github.com/rust-lang/rust --depth=1
-    - name: Create hello world crate
-      run: cargo new --bin /tmp/crate
-    - name: Build reference binary
-      run: |
-        cd rust
-        cp src/bootstrap/defaults/config.library.toml config.toml
-        cd library/backtrace
-        git fetch
-        git checkout ${{ github.event.pull_request.base.sha }}
-        cd ../..
-        python3 x.py build library --stage 0
-        ./build/x86_64-unknown-linux-gnu/stage0/bin/rustc -O /tmp/crate/src/main.rs -o binary-reference
-    - name: Build current binary
-      run: |
-        cd library/backtrace
-        git checkout ${{ github.sha }}
-        cd ../..
-        python3 x.py build library --stage 0
-        ./build/x86_64-unknown-linux-gnu/stage0/bin/rustc -O /tmp/crate/src/main.rs -o binary-updated
-    - name: Display binary size
-      run: |
-        ls -lha binary-*
+      - name: Print info
+        run: |
+          echo "Current SHA: ${{ github.event.pull_request.head.sha }}"
+          echo "Base SHA: ${{ github.event.pull_request.base.sha }}"
+      - name: Clone Rustc
+        run: |
+          git clone https://github.com/rust-lang/rust --depth=1
+          cd rust
+          git submodule update --init library/backtrace
+      - name: Create hello world crate
+        run: cargo new --bin /tmp/hello
+      - name: Build binary with base version of backtrace
+        run: |
+          cd rust
+          printf "[llvm]\ndownload-ci-llvm = true\n\n[rust]\nincremental = false\n" > config.toml
+          cd library/backtrace
+          git remote add kobzol https://github.com/kobzol/backtrace-rs
+          git fetch --all
+          git checkout ${{ github.event.pull_request.base.sha }}
+          cd ../..
+          git add library/backtrace
+          python3 x.py build library --stage 0
+          ./build/x86_64-unknown-linux-gnu/stage0/bin/rustc -O /tmp/hello/src/main.rs -o binary-reference
+      - name: Build binary with PR version of backtrace
+        run: |
+          cd rust
+          cd library/backtrace
+          git checkout ${{ github.event.pull_request.head.sha }}
+          cd ../..
+          git add library/backtrace
+          rm -rf build/x86_64-unknown-linux-gnu/stage0-std
+          python3 x.py build library --stage 0
+          ./build/x86_64-unknown-linux-gnu/stage0/bin/rustc -O /tmp/hello/src/main.rs -o binary-updated
+      - name: Display binary size
+        run: |
+          ls -la rust/binary-*
+          echo "SIZE_REFERENCE=$(stat -c '%s' rust/binary-reference)" >> "$GITHUB_ENV"
+          echo "SIZE_UPDATED=$(stat -c '%s' rust/binary-updated)" >> "$GITHUB_ENV"
+      - name: Post a PR comment if the size has changed
+        uses: actions/github-script@v6
+        with:
+          script: |
+            const reference = process.env.SIZE_REFERENCE;
+            const updated = process.env.SIZE_UPDATED;
+            const diff = updated - reference;
+            let diff_str = `${diff}B`;
+            if (diff > 0) {
+              diff_str = `+${diff_str}`;
+            }
+
+            if (diff !== 0) {
+              github.rest.issues.createComment({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                body: `Below is the size of a hello-world Rust program linked with libstd with backtrace.
+
+                  Original binary size: **${reference}B**
+                  Updated binary size: **${updated}B**
+                  Difference: **${diff_str}**`
+              })
+            }

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "backtrace"
-version = "0.3.68"
+version = "0.3.69"
 authors = ["The Rust Project Developers"]
 build = "build.rs"
 license = "MIT OR Apache-2.0"

src/capture.rs

@@ -8,6 +8,8 @@ use std::prelude::v1::*;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+pub const SHAKESPEARE: &str = include_str!("shakespeare.txt");
+
 /// Representation of an owned and self-contained backtrace.
 ///
 /// This structure can be used to capture a backtrace at various points in a
@@ -108,6 +110,11 @@ pub struct BacktraceSymbol {
     colno: Option<u32>,
 }
 
+#[allow(unused)]
+pub fn foo() {
+    println!("FOO");
+}
+
 impl Backtrace {
     /// Captures a backtrace at the callsite of this function, returning an
     /// owned representation.
@@ -137,6 +144,7 @@ impl Backtrace {
     /// enabled, and the `std` feature is enabled by default.
     #[inline(never)] // want to make sure there's a frame here to remove
     pub fn new() -> Backtrace {
+        println!("FOO");
         let mut bt = Self::create(Self::new as usize);
         bt.resolve();
         bt