From 8cfc9d1dde5ae0b3263ffea6a8afbe162759f9ca Mon Sep 17 00:00:00 2001
From: Blaine Bublitz <blaine@aztecprotocol.com>
Date: Tue, 7 Mar 2023 11:22:36 -0700
Subject: [PATCH] feat: Add pkgconfig output for installed target
 (https://github.com/AztecProtocol/barretenberg/pull/208)

* feat: Add pkgconfig output for installed target

* fix: Specify version with the project function

* chore: Add documentation to install targets
---
 circuits/cpp/barretenberg/cpp/CMakeLists.txt  |  8 +++++---
 .../barretenberg/cpp/cmake/barretenberg.pc.in | 12 +++++++++++
 .../barretenberg/cpp/src/aztec/CMakeLists.txt | 20 +++++++++++++++++++
 .../cpp/src/aztec/common/CMakeLists.txt       |  2 ++
 4 files changed, 39 insertions(+), 3 deletions(-)
 create mode 100644 circuits/cpp/barretenberg/cpp/cmake/barretenberg.pc.in

diff --git a/circuits/cpp/barretenberg/cpp/CMakeLists.txt b/circuits/cpp/barretenberg/cpp/CMakeLists.txt
index bff44b7bbf9..5cc744d9eda 100644
--- a/circuits/cpp/barretenberg/cpp/CMakeLists.txt
+++ b/circuits/cpp/barretenberg/cpp/CMakeLists.txt
@@ -3,10 +3,12 @@
 
 cmake_minimum_required(VERSION 3.24)
 
-set(PROJECT_VERSION 0.1.0)
-project(Barretenberg
+project(
+    Barretenberg
     DESCRIPTION "BN254 elliptic curve library, and PLONK SNARK prover"
-    LANGUAGES CXX C)
+    VERSION 0.1.0
+    LANGUAGES CXX C
+)
 
 option(DISABLE_ASM "Disable custom assembly" OFF)
 option(DISABLE_ADX "Disable ADX assembly variant" OFF)
diff --git a/circuits/cpp/barretenberg/cpp/cmake/barretenberg.pc.in b/circuits/cpp/barretenberg/cpp/cmake/barretenberg.pc.in
new file mode 100644
index 00000000000..6aecb0c9ad7
--- /dev/null
+++ b/circuits/cpp/barretenberg/cpp/cmake/barretenberg.pc.in
@@ -0,0 +1,12 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=${prefix}
+libdir=@CMAKE_INSTALL_FULL_LIBDIR@
+includedir=@CMAKE_INSTALL_FULL_INCLUDEDIR@
+
+Name: @PROJECT_NAME@
+Description: Optimized elliptic curve library for the bn128 curve, and PLONK SNARK prover
+Version: @PROJECT_VERSION@
+
+Libs: -L${libdir}
+Libs.private: -lomp
+Cflags: -I${includedir}
diff --git a/circuits/cpp/barretenberg/cpp/src/aztec/CMakeLists.txt b/circuits/cpp/barretenberg/cpp/src/aztec/CMakeLists.txt
index 301be6ab139..98a1e1a1586 100644
--- a/circuits/cpp/barretenberg/cpp/src/aztec/CMakeLists.txt
+++ b/circuits/cpp/barretenberg/cpp/src/aztec/CMakeLists.txt
@@ -168,11 +168,31 @@ else()
     )
 
     if(INSTALL_BARRETENBERG)
+        # The `install` function takes targets to install in different destinations on the system.
         install(
             TARGETS barretenberg barretenberg_headers
+            # We also give it an optional export name in case something wants to target the install.
             EXPORT barretenbergTargets
+            # The ARCHIVE output signifies static libraries that should be installed
+            # and we use the GNUInstallDirs location to install into the standard system library location
             ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            # The FILE_SET output is used instead of PUBLIC_HEADER & PRIVATE_HEADER outputs because
+            # our headers don't have a clear delineation between public & private, but we still use
+            # the GNUInstallDirs location to install into the standard system header location
             FILE_SET HEADERS DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
         )
+
+        set(pkg_config "${PROJECT_BINARY_DIR}/barretenberg.pc")
+
+        configure_file(
+            "${PROJECT_SOURCE_DIR}/cmake/barretenberg.pc.in"
+            "${pkg_config}"
+            @ONLY
+        )
+
+        install(
+            FILES "${pkg_config}"
+            DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig"
+        )
     endif()
 endif()
diff --git a/circuits/cpp/barretenberg/cpp/src/aztec/common/CMakeLists.txt b/circuits/cpp/barretenberg/cpp/src/aztec/common/CMakeLists.txt
index 4f815063ff4..612adc04b0f 100644
--- a/circuits/cpp/barretenberg/cpp/src/aztec/common/CMakeLists.txt
+++ b/circuits/cpp/barretenberg/cpp/src/aztec/common/CMakeLists.txt
@@ -1,4 +1,6 @@
 # Collect our common/*.hpp files and include in installation
+# This is only necessary because nothing in `common/` has an
+# implementation and doesn't use the `barretenberg_module` function
 file(GLOB_RECURSE HEADER_FILES *.hpp)
 target_sources(
     barretenberg_headers