Add better error reporting for cases where a package conflicts with a replace and not directly a package, fixes #9834

src/Composer/DependencyResolver/Rule.php

@@ -211,7 +211,40 @@ abstract class Rule
                 $package1 = $this->deduplicateDefaultBranchAlias($pool->literalToPackage($literals[0]));
                 $package2 = $this->deduplicateDefaultBranchAlias($pool->literalToPackage($literals[1]));
 
-                return $package2->getPrettyString().' conflicts with '.$package1->getPrettyString().'.';
+                $conflictTarget = $package1->getPrettyString();
+                if ($reasonData = $this->getReasonData()) {
+                    // swap literals if they are not in the right order with package2 being the conflicter
+                    if ($reasonData->getSource() === $package1->getName()) {
+                        list($package2, $package1) = array($package1, $package2);
+                    }
+
+                    // if the conflict is not directly against the package but something it provides/replaces,
+                    // we try to find that link to display a better message
+                    if ($reasonData->getTarget() !== $package1->getName()) {
+                        $provideType = null;
+                        $provided = null;
+                        foreach ($package1->getProvides() as $provide) {
+                            if ($provide->getTarget() === $reasonData->getTarget()) {
+                                $provideType = 'provides';
+                                $provided = $provide->getPrettyConstraint();
+                                break;
+                            }
+                        }
+                        foreach ($package1->getReplaces() as $replace) {
+                            if ($replace->getTarget() === $reasonData->getTarget()) {
+                                $provideType = 'replaces';
+                                $provided = $replace->getPrettyConstraint();
+                                break;
+                            }
+                        }
+                        if (null !== $provideType) {
+                            $conflictTarget = $reasonData->getTarget().' '.$reasonData->getPrettyConstraint().' ('.$package1->getPrettyString().' '.$provideType.' '.$reasonData->getTarget().' '.$provided.')';
+                        }
+                    }
+                }
+
+
+                return $package2->getPrettyString().' conflicts with '.$conflictTarget.'.';
 
             case self::RULE_PACKAGE_REQUIRES:
                 $sourceLiteral = array_shift($literals);

tests/Composer/Test/Fixtures/installer/conflict-against-provided-by-dep-package-works.test

@@ -0,0 +1,39 @@
+--TEST--
+Test that a conflict against a name that is provided by a dependency does not error
+--COMPOSER--
+{
+    "version": "1.2.3",
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                {
+                    "name": "conflicting/pkg",
+                    "version": "1.0.0",
+                    "conflict": {
+                        "provided/pkg2": "2.*"
+                    }
+                },
+                {
+                    "name": "provider/pkg",
+                    "version": "1.0.0",
+                    "provide": { "provided/pkg2": "2.*" }
+                }
+            ]
+        }
+    ],
+    "require": {
+        "conflicting/pkg": "*",
+        "provider/pkg": "*"
+    }
+}
+
+--RUN--
+update
+
+--EXPECT-EXIT-CODE--
+0
+
+--EXPECT--
+Installing conflicting/pkg (1.0.0)
+Installing provider/pkg (1.0.0)

tests/Composer/Test/Fixtures/installer/conflict-against-provided-package-works.test

@@ -0,0 +1,40 @@
+--TEST--
+Test that a conflict against a name that provided by the root does not error
+--COMPOSER--
+{
+    "version": "1.2.3",
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                {
+                    "name": "conflicting/pkg",
+                    "version": "1.0.0",
+                    "conflict": {
+                        "provided/pkg": "2.*"
+                    }
+                },
+                {
+                    "name": "provider/pkg",
+                    "version": "1.0.0",
+                    "provide": { "provided/pkg2": "2.0.5" }
+                }
+            ]
+        }
+    ],
+    "require": {
+        "conflicting/pkg": "*"
+    },
+    "provide": {
+        "provided/pkg": "2.*"
+    }
+}
+
+--RUN--
+update
+
+--EXPECT-EXIT-CODE--
+0
+
+--EXPECT--
+Installing conflicting/pkg (1.0.0)

tests/Composer/Test/Fixtures/installer/conflict-against-replaced-by-dep-package-problem.test

@@ -0,0 +1,48 @@
+--TEST--
+Test that a conflict against a name that is only replaced by a dependency correctly highlights the issue
+--COMPOSER--
+{
+    "version": "1.2.3",
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                {
+                    "name": "conflicting/pkg",
+                    "version": "1.0.0",
+                    "conflict": {
+                        "replaced/pkg2": ">=2.1"
+                    }
+                },
+                {
+                    "name": "provider/pkg",
+                    "version": "1.0.0",
+                    "replace": { "replaced/pkg2": "2.5" }
+                }
+            ]
+        }
+    ],
+    "require": {
+        "conflicting/pkg": "*",
+        "provider/pkg": "*"
+    }
+}
+
+--RUN--
+update
+
+--EXPECT-EXIT-CODE--
+2
+
+--EXPECT-OUTPUT--
+Loading composer repositories with package information
+Updating dependencies
+Your requirements could not be resolved to an installable set of packages.
+
+  Problem 1
+    - Root composer.json requires conflicting/pkg * -> satisfiable by conflicting/pkg[1.0.0].
+    - conflicting/pkg 1.0.0 conflicts with replaced/pkg2 >=2.1 (provider/pkg 1.0.0 replaces replaced/pkg2 2.5).
+    - Root composer.json requires provider/pkg * -> satisfiable by provider/pkg[1.0.0].
+
+--EXPECT--
+

tests/Composer/Test/Fixtures/installer/conflict-against-replaced-package-problem.test

@@ -0,0 +1,45 @@
+--TEST--
+Test that a conflict against a name that is only replaced by root correctly highlights the issue
+--COMPOSER--
+{
+    "version": "1.2.3",
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                {
+                    "name": "conflicting/pkg",
+                    "version": "1.0.0",
+                    "conflict": {
+                        "replaced/pkg": "2.*"
+                    }
+                }
+            ]
+        }
+    ],
+    "require": {
+        "conflicting/pkg": "*"
+    },
+    "replace": {
+        "replaced/pkg": "2.*"
+    }
+}
+
+--RUN--
+update
+
+--EXPECT-EXIT-CODE--
+2
+
+--EXPECT-OUTPUT--
+Loading composer repositories with package information
+Updating dependencies
+Your requirements could not be resolved to an installable set of packages.
+
+  Problem 1
+    - __root__ is present at version 1.2.3 and cannot be modified by Composer
+    - conflicting/pkg 1.0.0 conflicts with replaced/pkg 2.* (__root__ 1.2.3 replaces replaced/pkg 2.*).
+    - Root composer.json requires conflicting/pkg * -> satisfiable by conflicting/pkg[1.0.0].
+
+--EXPECT--
+