Build bundled library with Cargo directly, drop CMake (#48)

* Build bundled library with Cargo directly, drop CMake

CMake was only orchestrating Cargo: it ran `cargo build` (build.rs runs
cbindgen to emit the header), applied two textual fix-ups to that header,
and merged static archives. The merge folded in C utility objects this
package never links, and config.h / enum-string codegen are unused here.

Replace the CMake invocation in configure/configure.win with a direct
`cargo build --release`, reproduce the two header fix-ups with sed
(A_M... -> AM_..., USIZE_ -> pointer size via .Machine$sizeof.pointer),
and stage libautomerge_core.a as am-install/lib/libautomerge.a. The
install layout is unchanged, so Makevars need no edits.

Express the bundled-source changes in the tools workflow: patch-sources.sh
now generates Cargo.toml and cbindgen.toml from the upstream cmake/*.in
templates (as CMake's configure_file did) and removes CMakeLists.txt and
cmake/, instead of patching CMakeLists.txt. The obsolete CMakeLists
patches are dropped from patch-rust-msrv.sh and vendor-deps.sh. The
generated TOMLs reproduce the committed ones byte-for-byte.

Drop CMake >= 3.25 from SystemRequirements; Rust (Cargo + rustc >= 1.85)
is now the only build toolchain. Update README, vignette, NEWS, cleanup.

* Update news

Author: shikokuchuo

DESCRIPTION

@@ -38,5 +38,5 @@ Config/roxygen2/markdown: TRUE
 Config/roxygen2/version: 8.0.0
 Config/testthat/edition: 3
 Encoding: UTF-8
-SystemRequirements: 'automerge-c', or Cargo (Rust's package manager),
-    rustc >= 1.85 and CMake >= 3.25 to build from package sources.
+SystemRequirements: 'automerge-c', or Cargo (Rust's package manager) and
+    rustc >= 1.85 to build from package sources.

NEWS.md

@@ -1,5 +1,7 @@
 # automerge (development version)
 
+* Building the bundled automerge library from source no longer requires CMake.
+
 * Updates vendored automerge library to 0.10.0.
 
 # automerge 0.4.0

README.Rmd

@@ -70,7 +70,7 @@ bob
 install.packages("automerge")
 ```
 
-Building from source requires Rust >= 1.85 ([rustup.rs](https://rustup.rs/)) and CMake >= 3.25 (included in Rtools43+ on Windows).
+Building from source requires Rust >= 1.85 ([rustup.rs](https://rustup.rs/); included in Rtools43+ on Windows).
 
 ## Documentation
 

README.md

@@ -85,8 +85,7 @@ install.packages("automerge")
 ```
 
 Building from source requires Rust \>= 1.85
-([rustup.rs](https://rustup.rs/)) and CMake \>= 3.25 (included in
-Rtools43+ on Windows).
+([rustup.rs](https://rustup.rs/); included in Rtools43+ on Windows).
 
 ## Documentation
 

cleanup

@@ -3,8 +3,5 @@
 rm -f src/Makevars src/Makevars.win
 rm -f src/*.o src/*.so src/*.dll src/symbols.rds
 rm -rf am-build am-install
-rm -rf src/automerge/rust/automerge-c/build
-rm -f src/automerge/rust/automerge-c/cmake_config.log
-rm -f src/automerge/rust/automerge-c/cmake_build.log
 rm -rf src/automerge/rust/target
 rm -rf src/automerge/rust/vendor

configure

@@ -10,19 +10,6 @@ CFLAGS=`"${R_HOME}/bin/R" CMD config CFLAGS`
 LDFLAGS=`"${R_HOME}/bin/R" CMD config LDFLAGS`
 export CC CFLAGS LDFLAGS
 
-# Helper function: detect cmake
-detect_cmake() {
-  if command -v cmake >/dev/null 2>&1; then
-    return 0
-  fi
-  export PATH=$PATH:/Applications/CMake.app/Contents/bin
-  if command -v cmake >/dev/null 2>&1; then
-    return 0
-  fi
-  echo "ERROR: CMake not found"
-  exit 1
-}
-
 # Helper function: check for UTF-32 indexing in system library
 check_utf32_indexing() {
     echo "#include <automerge-c/config.h>
@@ -146,9 +133,7 @@ if [ ${AUTOMERGE_FOUND} -eq 0 ]; then
         exit 1
     fi
 
-    detect_cmake
-
-    echo "Building automerge-c..."
+    echo "Building automerge-c from bundled source..."
     echo "using Rust package manager: '$($CARGO_CMD --version)'"
     echo "using Rust compiler: '$($RUSTC_CMD --version)'"
 
@@ -162,6 +147,13 @@ if [ ${AUTOMERGE_FOUND} -eq 0 ]; then
     export CARGO_HOME="${PWD}/am-build/.cargo"
     mkdir -p "$CARGO_HOME"
 
+    # Keep Cargo's build artefacts inside the package build tree
+    export CARGO_TARGET_DIR="${PWD}/am-build/target"
+
+    # automerge-c's build.rs writes the cbindgen-generated header here
+    export CBINDGEN_TARGET_DIR="${PWD}/am-install/include/automerge-c"
+    mkdir -p "$CBINDGEN_TARGET_DIR" am-install/lib
+
     # Generate vendor config with absolute path (env vars don't work for source replacement)
     cat > "$CARGO_HOME/config.toml" << EOF
 [source.crates-io]
@@ -171,36 +163,38 @@ replace-with = "vendored-sources"
 directory = "${PWD}/src/automerge/rust/vendor"
 EOF
 
-    # Extract vendored Rust dependencies (CMakeLists.txt configures Cargo to use them)
+    # Extract vendored Rust dependencies
     if [ -f "src/automerge/rust/vendor.tar.xz" ] && [ ! -d "src/automerge/rust/vendor" ]; then
         echo "Extracting vendored Rust dependencies..."
         xz -dc src/automerge/rust/vendor.tar.xz | tar -xf - -C src/automerge/rust
     fi
 
-    cmake -S src/automerge/rust/automerge-c -B am-build \
-        -DCMAKE_BUILD_TYPE=Release \
-        -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
-        -DCMAKE_INSTALL_PREFIX="${PWD}/am-install" \
-        -DCMAKE_INSTALL_LIBDIR=lib \
-        -DBUILD_TESTING=OFF \
-        -DCMAKE_COLOR_MAKEFILE=OFF \
-        -DCMAKE_INSTALL_MESSAGE=NEVER \
-        -DUTF32_INDEXING=ON \
-        || { echo "ERROR: CMake configuration failed"; exit 1; }
-
     echo "Building (this may take several minutes)..."
-    cmake --build am-build --config Release \
-        || { echo "ERROR: Build failed"; exit 1; }
+    # Default features select UTF-32 indexing; -j2 respects CRAN's core limit.
+    # build.rs runs cbindgen to emit ${CBINDGEN_TARGET_DIR}/automerge.h.
+    "$CARGO_CMD" build --release -j2 \
+        --manifest-path src/automerge/rust/automerge-c/Cargo.toml \
+        || { echo "ERROR: cargo build failed"; exit 1; }
+
+    HEADER="am-install/include/automerge-c/automerge.h"
+    if [ ! -f "$HEADER" ]; then
+        echo "ERROR: cbindgen did not generate ${HEADER}"
+        exit 1
+    fi
 
-    cmake --build am-build --target install \
-        || { echo "ERROR: Install failed"; exit 1; }
+    # Post-process the cbindgen header (work previously done by CMake):
+    #   1. cbindgen renders consecutive capitals as "A_M..."; restore "AM_...".
+    #   2. cbindgen ignores size_of::<usize>(); substitute the pointer size.
+    PTR_SIZE=`"${R_HOME}/bin/Rscript" -e 'cat(.Machine$sizeof.pointer)'`
+    sed -e 's/A_M\([^_][^_]*\)_/AM_\1_/g' \
+        -e "s/USIZE_/+${PTR_SIZE}/g" \
+        "$HEADER" > "${HEADER}.tmp" && mv "${HEADER}.tmp" "$HEADER"
 
-    rm -rf am-build
+    # Stage the static library where Makevars expects it
+    cp am-build/target/release/libautomerge_core.a am-install/lib/libautomerge.a \
+        || { echo "ERROR: failed to stage static library"; exit 1; }
 
-    if [ ! -d "am-install/lib" ]; then
-        echo "ERROR: Installation did not create expected lib directory"
-        exit 1
-    fi
+    rm -rf am-build
 
     echo "Successfully built automerge-c from source"
 

configure.win

@@ -10,16 +10,6 @@ CFLAGS=`"${R_HOME}/bin/R" CMD config CFLAGS`
 LDFLAGS=`"${R_HOME}/bin/R" CMD config LDFLAGS`
 export CC CFLAGS LDFLAGS
 
-# Helper function: detect cmake
-detect_cmake() {
-  if command -v cmake >/dev/null 2>&1; then
-    return 0
-  fi
-  echo "ERROR: CMake not found"
-  echo "CMake is included in Rtools43+"
-  exit 1
-}
-
 # Helper function: check for UTF-32 indexing in system library
 check_utf32_indexing() {
     echo "#include <automerge-c/config.h>
@@ -125,9 +115,7 @@ if [ ${AUTOMERGE_FOUND} -eq 0 ]; then
         echo "Note: Configuring Rust to use GNU toolchain for Rtools compatibility"
     fi
 
-    detect_cmake
-
-    echo "Building automerge-c..."
+    echo "Building automerge-c from bundled source..."
     echo "using Rust package manager: '$($CARGO_CMD --version)'"
     echo "using Rust compiler: '$($RUSTC_CMD --version)'"
 
@@ -141,6 +129,13 @@ if [ ${AUTOMERGE_FOUND} -eq 0 ]; then
     export CARGO_HOME="${PWD}/am-build/.cargo"
     mkdir -p "$CARGO_HOME"
 
+    # Keep Cargo's build artefacts inside the package build tree
+    export CARGO_TARGET_DIR="${PWD}/am-build/target"
+
+    # automerge-c's build.rs writes the cbindgen-generated header here
+    export CBINDGEN_TARGET_DIR="${PWD}/am-install/include/automerge-c"
+    mkdir -p "$CBINDGEN_TARGET_DIR" am-install/lib
+
     # Generate vendor config with absolute path (env vars don't work for source replacement)
     # Use pwd -W to get Windows-style path (MSYS2 bash built-in)
     WIN_PWD=$(pwd -W)
@@ -152,7 +147,7 @@ replace-with = "vendored-sources"
 directory = "${WIN_PWD}/src/automerge/rust/vendor"
 EOF
 
-    # Extract vendored Rust dependencies (CMakeLists.txt configures Cargo to use them)
+    # Extract vendored Rust dependencies
     if [ -f "src/automerge/rust/vendor.tar.xz" ] && [ ! -d "src/automerge/rust/vendor" ]; then
         echo "Extracting vendored Rust dependencies..."
         xz -dc src/automerge/rust/vendor.tar.xz | tar -xf - -C src/automerge/rust
@@ -161,31 +156,32 @@ EOF
     # Force GNU target to match MinGW toolchain from Rtools
     export RUSTUP_TOOLCHAIN="stable-x86_64-pc-windows-gnu"
 
-    cmake -G "Unix Makefiles" \
-        -S src/automerge/rust/automerge-c -B am-build \
-        -DCMAKE_BUILD_TYPE=Release \
-        -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
-        -DCMAKE_INSTALL_PREFIX="${PWD}/am-install" \
-        -DCMAKE_INSTALL_LIBDIR=lib \
-        -DBUILD_TESTING=OFF \
-        -DCMAKE_COLOR_MAKEFILE=OFF \
-        -DCMAKE_INSTALL_MESSAGE=NEVER \
-        -DUTF32_INDEXING=ON \
-        || { echo "ERROR: CMake configuration failed"; exit 1; }
-
     echo "Building (this may take several minutes)..."
-    cmake --build am-build --config Release \
-        || { echo "ERROR: Build failed"; exit 1; }
+    # Default features select UTF-32 indexing; -j2 respects CRAN's core limit.
+    # build.rs runs cbindgen to emit ${CBINDGEN_TARGET_DIR}/automerge.h.
+    "$CARGO_CMD" build --release -j2 \
+        --manifest-path src/automerge/rust/automerge-c/Cargo.toml \
+        || { echo "ERROR: cargo build failed"; exit 1; }
+
+    HEADER="am-install/include/automerge-c/automerge.h"
+    if [ ! -f "$HEADER" ]; then
+        echo "ERROR: cbindgen did not generate ${HEADER}"
+        exit 1
+    fi
 
-    cmake --build am-build --target install \
-        || { echo "ERROR: Install failed"; exit 1; }
+    # Post-process the cbindgen header (work previously done by CMake):
+    #   1. cbindgen renders consecutive capitals as "A_M..."; restore "AM_...".
+    #   2. cbindgen ignores size_of::<usize>(); substitute the pointer size.
+    PTR_SIZE=`"${R_HOME}/bin/Rscript" -e 'cat(.Machine$sizeof.pointer)'`
+    sed -e 's/A_M\([^_][^_]*\)_/AM_\1_/g' \
+        -e "s/USIZE_/+${PTR_SIZE}/g" \
+        "$HEADER" > "${HEADER}.tmp" && mv "${HEADER}.tmp" "$HEADER"
 
-    rm -rf am-build
+    # Stage the static library where Makevars expects it
+    cp am-build/target/release/libautomerge_core.a am-install/lib/libautomerge.a \
+        || { echo "ERROR: failed to stage static library"; exit 1; }
 
-    if [ ! -d "am-install/lib" ]; then
-        echo "ERROR: Installation did not create expected lib directory"
-        exit 1
-    fi
+    rm -rf am-build
 
     echo "Successfully built automerge-c from source"