Reduce amount of packages loaded by avoiding extensions of the constraint beyond the root constraint

src/Composer/DependencyResolver/PoolBuilder.php

@@ -80,6 +80,16 @@ class PoolBuilder
     private $unacceptableFixedPackages = array();
     private $updateAllowList = array();
     private $skippedLoad = array();
+
+    /**
+     * Keeps a list of dependencies which are root requirements, and as such
+     * have already their maximum required range loaded and can not be
+     * extended by markPackageNameForLoading
+     *
+     * Packages get cleared from this list if they get unfixed as in that case
+     * we need to actually load them
+     */
+    private $maxExtendedReqs = array();
     /**
      * @psalm-var array<string, bool>
      */
@@ -156,7 +166,8 @@ class PoolBuilder
                 continue;
             }
 
-            $this->markPackageNameForLoading($request, $packageName, $constraint);
+            $this->packagesToLoad[$packageName] = $constraint;
+            $this->maxExtendedReqs[$packageName] = true;
         }
 
         // clean up packagesToLoad for anything we manually marked loaded above
@@ -225,6 +236,21 @@ class PoolBuilder
 
     private function markPackageNameForLoading(Request $request, $name, ConstraintInterface $constraint)
     {
+        // Root require (which was not unfixed) already loaded the maximum range so no
+        // need to check anything here
+        if (isset($this->maxExtendedReqs[$name])) {
+            return;
+        }
+
+        // Root requires can not be overruled by dependencies so there is no point in
+        // extending the loaded constraint for those.
+        // This is triggered when loading a root require which was fixed but got unfixed, then
+        // we make sure that we load at most the intervals covered by the root constraint.
+        $rootRequires = $request->getRequires();
+        if (isset($rootRequires[$name]) && !Intervals::isSubsetOf($constraint, $rootRequires[$name])) {
+            $constraint = $rootRequires[$name];
+        }
+
         // Maybe it was already marked before but not loaded yet. In that case
         // we have to extend the constraint (we don't check if they match because
         // MultiConstraint::create() will optimize anyway)
@@ -457,6 +483,7 @@ class PoolBuilder
 
         unset($this->skippedLoad[$name]);
         unset($this->loadedPackages[$name]);
+        unset($this->maxExtendedReqs[$name]);
     }
 
     private function removeLoadedPackage(Request $request, PackageInterface $package, $index)

tests/Composer/Test/DependencyResolver/Fixtures/poolbuilder/alias-priority-conflicting.test

@@ -50,12 +50,8 @@ Check root aliases are loaded
 
 --EXPECT--
 [
-    "package/a-dev-master",
-    "package/a-9999999-dev (alias of dev-master)",
     "req/pkg-dev-feature-foo#feat.f",
     "req/pkg-dev-master#feat.f (alias of dev-feature-foo)",
-    "req/pkg-dev-master#forked",
+    "package/a-dev-master",
-    "req/pkg-dev-master#master",
+    "package/a-9999999-dev (alias of dev-master)"
-    "req/pkg-1.0.9999999.9999999-dev#forked (alias of dev-master)",
-    "req/pkg-1.0.9999999.9999999-dev#master (alias of dev-master)"
 ]

tests/Composer/Test/DependencyResolver/Fixtures/poolbuilder/alias-with-reference.test

@@ -49,9 +49,8 @@ Check root aliases get selected correctly
 
 --EXPECT--
 [
-    "b/requirer-1.0.0.0#1.0.0",
     "a/aliased-dev-master#abcd",
     "a/aliased-1.0.0.0#abcd (alias of dev-master)",
-    "a/aliased-1.0.0.0#abcd",
+    "b/requirer-1.0.0.0#1.0.0",
     "a/aliased-9999999-dev#abcd (alias of dev-master)"
 ]

tests/Composer/Test/DependencyResolver/Fixtures/poolbuilder/partial-update-transitive-deps-unfix.test

@@ -5,12 +5,14 @@ Partially updating one root requirement with transitive deps fully updates anoth
 {
     "require": {
         "root/update": "*",
-        "root/dep": "*"
+        "root/dep": "1.0.*",
+        "root/dep2": "*"
     },
     "locked": [
         {"name": "root/update", "version": "1.0.1", "require": {"dep/dep": "1.*"}},
-        {"name": "dep/dep", "version": "1.0.2", "require": {"root/dep": "1.*"}},
+        {"name": "dep/dep", "version": "1.0.2", "require": {"root/dep": "1.*", "root/dep2": "1.*"}},
-        {"name": "root/dep", "version": "1.0.3"}
+        {"name": "root/dep", "version": "1.0.3"},
+        {"name": "root/dep2", "version": "1.0.3"}
     ],
     "allowList": [
         "root/update"
@@ -28,8 +30,10 @@ Partially updating one root requirement with transitive deps fully updates anoth
     {"name": "root/update", "version": "1.0.5", "require": {"dep/dep": "2.*"}},
     {"name": "root/dep", "version": "1.0.6"},
     {"name": "root/dep", "version": "2.0.7"},
-    {"name": "dep/dep", "version": "1.0.8", "require": {"root/dep": "1.*"}},
+    {"name": "root/dep2", "version": "1.0.6"},
-    {"name": "dep/dep", "version": "2.0.9", "require": {"root/dep": "2.*"}}
+    {"name": "root/dep2", "version": "2.0.7"},
+    {"name": "dep/dep", "version": "1.0.8", "require": {"root/dep": "1.*", "root/dep2": "1.*"}},
+    {"name": "dep/dep", "version": "2.0.9", "require": {"root/dep": "2.*", "root/dep2": "2.*"}}
 ]
 
 --EXPECT--
@@ -39,5 +43,6 @@ Partially updating one root requirement with transitive deps fully updates anoth
    "dep/dep-1.0.8.0",
    "dep/dep-2.0.9.0",
    "root/dep-1.0.6.0",
-   "root/dep-2.0.7.0"
+   "root/dep2-1.0.6.0",
+   "root/dep2-2.0.7.0"
 ]