Merge bitcoin-core/secp256k1#964: Add release-process.md

3ed0d02 doc: add CHANGELOG template (Jonas Nick)
6f42dc1 doc: add release_process.md (Jonas Nick)
0bd3e42 build: set library version to 0.0.0 explicitly (Jonas Nick)
b4b02fd build: change libsecp version from 0.1 to 0.1.0-pre (Jonas Nick)

Pull request description:

  This is an attempt at a simple release process. Fixes bitcoin#856. To keep it simple, there is no concept of release candidates for now.

  The release version is determined by semantic versioning of the API. Since it does not seem to be a lot of work, it is proper to also version the ABI with the libtool versioning system. This versioning scheme (semver API, libtool versioning ABI) follows the suggestion in the [autotools mythbusters](https://autotools.io/libtool/version.html).

  Experimental modules are a bit of a headache, as expected. This release process suggests to treat any change in experimental modules as backwards compatible. That way, users of stable modules are not bothered by frequent non-backwards compatible releases. But a downside is that one must not use experimental modules in shared libraries (which should be mentioned in the README?). It would be nice if we could make the schnorrsig module stable in the not too distant future (see also bitcoin#817).

ACKs for top commit:
  apoelstra:
    utACK 3ed0d02
  elichai:
    ACK 3ed0d02
  sipa:
    ACK 3ed0d02
  real-or-random:
    ACK 3ed0d02

Tree-SHA512: 25a04335a9579e16de48d378b93a9c6a248529f67f7c436680fa2d495192132743ce016c547aa9718cdcc7fe932de31dd7594f49052e8bd85572a84264f2dbee

Makefile.am

@@ -88,7 +88,7 @@ endif
 libsecp256k1_la_SOURCES = src/secp256k1.c
 libsecp256k1_la_CPPFLAGS = -I$(top_srcdir)/include -I$(top_srcdir)/src $(SECP_INCLUDES)
 libsecp256k1_la_LIBADD = $(SECP_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
-libsecp256k1_la_LDFLAGS = -no-undefined
+libsecp256k1_la_LDFLAGS = -no-undefined -version-info $(LIB_VERSION_CURRENT):$(LIB_VERSION_REVISION):$(LIB_VERSION_AGE)
 
 if VALGRIND_ENABLED
 libsecp256k1_la_CPPFLAGS += -DVALGRIND

configure.ac

@@ -1,5 +1,24 @@
 AC_PREREQ([2.60])
-AC_INIT([libsecp256k1],[0.1])
+
+# The package (a.k.a. release) version is based on semantic versioning 2.0.0 of
+# the API. All changes in experimental modules are treated as
+# backwards-compatible and therefore at most increase the minor version.
+define(_PKG_VERSION_MAJOR, 0)
+define(_PKG_VERSION_MINOR, 1)
+define(_PKG_VERSION_BUILD, 0)
+define(_PKG_VERSION_IS_RELEASE, false)
+
+# The library version is based on libtool versioning of the ABI. The set of
+# rules for updating the version can be found here:
+# https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
+# All changes in experimental modules are treated as if they don't affect the
+# interface and therefore only increase the revision.
+define(_LIB_VERSION_CURRENT, 0)
+define(_LIB_VERSION_REVISION, 0)
+define(_LIB_VERSION_AGE, 0)
+
+AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_BUILD)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-pre]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1])
+
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
 AC_CANONICAL_HOST
@@ -381,6 +400,9 @@ AM_CONDITIONAL([ENABLE_MODULE_EXTRAKEYS], [test x"$enable_module_extrakeys" = x"
 AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"])
 AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$use_external_asm" = x"yes"])
 AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm"])
+AC_SUBST(LIB_VERSION_CURRENT, _LIB_VERSION_CURRENT)
+AC_SUBST(LIB_VERSION_REVISION, _LIB_VERSION_REVISION)
+AC_SUBST(LIB_VERSION_AGE, _LIB_VERSION_AGE)
 
 # Make sure nothing new is exported so that we don't break the cache.
 PKGCONFIG_PATH_TEMP="$PKG_CONFIG_PATH"

doc/CHANGELOG.md

@@ -0,0 +1,12 @@
+# Changelog
+
+This file is currently only a template for future use.
+
+Each change falls into one of the following categories: Added, Changed, Deprecated, Removed, Fixed or Security.
+
+## [Unreleased]
+
+## [MAJOR.MINOR.PATCH] - YYYY-MM-DD
+
+### Added/Changed/Deprecated/Removed/Fixed/Security
+- [Title with link to Pull Request](https://link-to-pr)

doc/release-process.md

@@ -0,0 +1,14 @@
+# Release Process
+
+1. Open PR to master that
+   1. adds release notes to `doc/CHANGELOG.md` and
+   2. if this is **not** a patch release, updates `_PKG_VERSION_{MAJOR,MINOR}` and `_LIB_VERSIONS_*` in `configure.ac`
+2. After the PR is merged,
+   * if this is **not** a patch release, create a release branch with name `MAJOR.MINOR`.
+     Make sure that the branch contains the right commits.
+     Create commit on the release branch that sets `_PKG_VERSION_IS_RELEASE` in `configure.ac` to `true`.
+   * if this **is** a patch release, open a pull request with the bugfixes to the `MAJOR.MINOR` branch.
+     Also include the release note commit bump `_PKG_VERSION_BUILD` and `_LIB_VERSIONS_*` in `configure.ac`.
+4. Tag the commit with `git tag -s vMAJOR.MINOR.PATCH`.
+5. Push branch and tag with `git push origin --tags`.
+6. Create a new GitHub release with a link to the corresponding entry in `doc/CHANGELOG.md`.