Order pre-releases of the same version by their identifiers

Two pre-releases of one major.minor.patch fell through to "not newer",
so 0.3.0-rc.2 was not an update over 0.3.0-rc.1. #205 asks for both that
and the release-over-pre-release case; the previous commit covered only
the latter.

prerelease_gt walks the dot-separated identifiers the way SemVer 11.4
describes: numeric ones compare as numbers so rc.11 outranks rc.2,
a numeric identifier ranks below an alphanumeric one, alphanumeric ones
compare byte-wise under LC_ALL=C so the locale cannot decide whether beta
sorts above alpha, and with every shared identifier equal the shorter
list ranks lower.

Build metadata is stripped before anything else. It never affects
precedence, and because it may contain '-' it had to go before the
pre-release split -- on main, 1.0.0+build.9 reached the numeric compare
as a patch of "0+build.9" and errored out.

The tests walk the precedence chain semver.org gives for 11.4 in both
directions, plus the two rows #205 lists and the build-metadata cases.
All of them fail on main.

Author: JspIIV

arcup/arcup

@@ -265,6 +265,11 @@ version_gt() {
     local ver1="${1#v}"
     local ver2="${2#v}"
 
+    # Build metadata never affects precedence (SemVer 10), and it may itself
+    # contain '-', so it has to go before the pre-release split below.
+    ver1="${ver1%%+*}"
+    ver2="${ver2%%+*}"
+
     # Keep the pre-release tags aside: SemVer orders a release above any
     # pre-release of the same major.minor.patch.
     local pre1="" pre2=""
@@ -292,13 +297,73 @@ EOF
     [ "$patch1" -gt "$patch2" ] && return 0
     [ "$patch1" -lt "$patch2" ] && return 1
 
-    # Same major.minor.patch. A release outranks a pre-release of it, so
-    # 0.3.0 is newer than 0.3.0-rc.1. Two pre-releases of the same version
-    # are not ordered here; no caller compares them.
-    if [ -z "$pre1" ] && [ -n "$pre2" ]; then
+    # Same major.minor.patch. A release outranks any pre-release of it, so
+    # 0.3.0 is newer than 0.3.0-rc.1 (SemVer 11.3). Two pre-releases are
+    # ordered identifier by identifier (SemVer 11.4).
+    if [ -z "$pre1" ] && [ -z "$pre2" ]; then
+        return 1
+    fi
+    if [ -z "$pre1" ]; then
         return 0
     fi
+    if [ -z "$pre2" ]; then
+        return 1
+    fi
+    prerelease_gt "$pre1" "$pre2"
+}
+
+# Order two dot-separated pre-release identifier lists (SemVer 11.4).
+# Returns 0 when the first ranks higher, 1 otherwise.
+prerelease_gt() {
+    local a="$1" b="$2"
+    local ia ib na nb
+    # Byte-wise comparison for the alphanumeric case; the locale must not
+    # decide whether "beta" sorts above "alpha".
+    local LC_ALL=C
+
+    while [ -n "$a" ] || [ -n "$b" ]; do
+        # With every shared identifier equal, the shorter list ranks lower
+        # (11.4.4): 1.0.0-alpha < 1.0.0-alpha.1.
+        if [ -z "$a" ]; then
+            return 1
+        fi
+        if [ -z "$b" ]; then
+            return 0
+        fi
+
+        ia="${a%%.*}"
+        ib="${b%%.*}"
+        if [ "$a" = "$ia" ]; then a=""; else a="${a#*.}"; fi
+        if [ "$b" = "$ib" ]; then b=""; else b="${b#*.}"; fi
 
+        if [ "$ia" = "$ib" ]; then
+            continue
+        fi
+
+        na=0; nb=0
+        case "$ia" in ''|*[!0-9]*) ;; *) na=1 ;; esac
+        case "$ib" in ''|*[!0-9]*) ;; *) nb=1 ;; esac
+
+        # Both numeric: compare as numbers, so rc.11 is newer than rc.2 (11.4.1).
+        if [ "$na" = 1 ] && [ "$nb" = 1 ]; then
+            if [ "$ia" -gt "$ib" ]; then
+                return 0
+            fi
+            return 1
+        fi
+        # A numeric identifier ranks below an alphanumeric one (11.4.3).
+        if [ "$na" = 1 ]; then
+            return 1
+        fi
+        if [ "$nb" = 1 ]; then
+            return 0
+        fi
+        # Both alphanumeric: ASCII order (11.4.2).
+        if [[ "$ia" > "$ib" ]]; then
+            return 0
+        fi
+        return 1
+    done
     return 1
 }
 

arcup/test_arcup.sh

@@ -76,6 +76,73 @@ test_version_comparison() {
     pass "release is newer than its prerelease with v prefix"
 }
 
+# The precedence chain semver.org gives for section 11.4, checked link by link
+# in both directions, plus the two pre-release comparisons #205 asks for.
+test_prerelease_precedence() {
+    local chain=(
+        "1.0.0-alpha"
+        "1.0.0-alpha.1"
+        "1.0.0-alpha.beta"
+        "1.0.0-beta"
+        "1.0.0-beta.2"
+        "1.0.0-beta.11"
+        "1.0.0-rc.1"
+        "1.0.0"
+    )
+    local i lower higher
+    for ((i = 1; i < ${#chain[@]}; i++)); do
+        lower="${chain[i-1]}"
+        higher="${chain[i]}"
+        if ! version_gt "$higher" "$lower"; then
+            fail "$higher is newer than $lower"
+        fi
+        if version_gt "$lower" "$higher"; then
+            fail "$lower is not newer than $higher"
+        fi
+    done
+    pass "orders the semver.org 11.4 chain"
+
+    if ! version_gt "0.3.0-rc.2" "0.3.0-rc.1"; then
+        fail "later release candidate is newer"
+    fi
+    pass "later release candidate is newer"
+
+    if ! version_gt "1.0.0-beta.11" "1.0.0-beta.2"; then
+        fail "numeric identifiers compare as numbers, not strings"
+    fi
+    pass "numeric identifiers compare as numbers, not strings"
+
+    if version_gt "1.0.0-rc.1" "1.0.0-rc.1"; then
+        fail "equal prereleases are not newer"
+    fi
+    pass "equal prereleases are not newer"
+}
+
+test_build_metadata_is_ignored() {
+    if version_gt "1.0.0+build.9" "1.0.0+build.1"; then
+        fail "build metadata does not order releases"
+    fi
+    pass "build metadata does not order releases"
+
+    if version_gt "1.0.0+build-1" "1.0.0"; then
+        fail "a hyphen inside build metadata is not a prerelease"
+    fi
+    if version_gt "1.0.0" "1.0.0+build-1"; then
+        fail "a hyphen inside build metadata is not a prerelease"
+    fi
+    pass "a hyphen inside build metadata is not a prerelease"
+
+    if ! version_gt "1.0.1+build-1" "1.0.0"; then
+        fail "the core still compares under build metadata"
+    fi
+    pass "the core still compares under build metadata"
+
+    if ! version_gt "1.0.0-rc.2+b1" "1.0.0-rc.1+b99"; then
+        fail "prerelease decides when both carry build metadata"
+    fi
+    pass "prerelease decides when both carry build metadata"
+}
+
 test_target_mapping() {
     assert_eq "x86_64-unknown-linux-gnu" "$(detect_target "linux" "amd64")" "maps linux amd64 target"
     assert_eq "aarch64-unknown-linux-gnu" "$(detect_target "linux" "arm64")" "maps linux arm64 target"
@@ -822,6 +889,8 @@ test_install_binary_rejects_symlink() {
 
 test_version_normalization
 test_version_comparison
+test_prerelease_precedence
+test_build_metadata_is_ignored
 test_target_mapping
 test_unknown_architecture_fails
 test_github_api_url_rejects_non_https