Config error only when flake8-import-conventions alias conflicts with isort.required-imports bound name (#15918)

Previously an error was emitted any time the configuration required both
an import of a module and an alias for that module. However, required
imports could themselves contain an alias, which may or may not agree
with the required alias.

To wit: requiring `import pandas as pd` does not conflict with the
`flake8-import-conventions.alias` config `{"pandas":"pd"}`.

This PR refines the check before throwing an error.

Closes #15911

crates/ruff/tests/lint.rs

@@ -2175,6 +2175,20 @@ fn flake8_import_convention_unused_aliased_import() {
         .pass_stdin("1"));
 }
 
+#[test]
+fn flake8_import_convention_unused_aliased_import_no_conflict() {
+    assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
+        .args(STDIN_BASE_OPTIONS)
+        .arg("--config")
+        .arg(r#"lint.isort.required-imports = ["import pandas as pd"]"#)
+        .args(["--select", "I002,ICN001,F401"])
+        .args(["--stdin-filename", "test.py"])
+        .arg("--unsafe-fixes")
+        .arg("--fix")
+        .arg("-")
+        .pass_stdin("1"));
+}
+
 /// Test that private, old-style `TypeVar` generics
 /// 1. Get replaced with PEP 695 type parameters (UP046, UP047)
 /// 2. Get renamed to remove leading underscores (UP049)

crates/ruff/tests/snapshots/lint__flake8_import_convention_unused_aliased_import_no_conflict.snap

@@ -0,0 +1,27 @@
+---
+source: crates/ruff/tests/lint.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--no-cache"
+    - "--output-format"
+    - concise
+    - "--config"
+    - "lint.isort.required-imports = [\"import pandas as pd\"]"
+    - "--select"
+    - "I002,ICN001,F401"
+    - "--stdin-filename"
+    - test.py
+    - "--unsafe-fixes"
+    - "--fix"
+    - "-"
+  stdin: "1"
+---
+success: true
+exit_code: 0
+----- stdout -----
+import pandas as pd
+1
+----- stderr -----
+Found 1 error (1 fixed, 0 remaining).

crates/ruff_python_semantic/src/imports.rs

@@ -43,7 +43,7 @@ impl NameImports {
 
 impl NameImport {
     /// Returns the name under which the member is bound (e.g., given `from foo import bar as baz`, returns `baz`).
-    fn bound_name(&self) -> &str {
+    pub fn bound_name(&self) -> &str {
         match self {
             NameImport::Import(import) => {
                 import.name.as_name.as_deref().unwrap_or(&import.name.name)

crates/ruff_workspace/src/configuration.rs

@@ -1576,9 +1576,20 @@ fn conflicting_import_settings(
     use std::fmt::Write;
     let mut err_body = String::new();
     for required_import in &isort.required_imports {
-        let name = required_import.qualified_name().to_string();
-        if let Some(alias) = flake8_import_conventions.aliases.get(&name) {
-            writeln!(err_body, "    - `{name}` -> `{alias}`").unwrap();
+        // Ex: `from foo import bar as baz` OR `import foo.bar as baz`
+        // - qualified name: `foo.bar`
+        // - bound name: `baz`
+        // - conflicts with: `{"foo.bar":"buzz"}`
+        // - does not conflict with either of
+        //   - `{"bar":"buzz"}`
+        //   - `{"foo.bar":"baz"}`
+        let qualified_name = required_import.qualified_name().to_string();
+        let bound_name = required_import.bound_name();
+        let Some(alias) = flake8_import_conventions.aliases.get(&qualified_name) else {
+            continue;
+        };
+        if alias != bound_name {
+            writeln!(err_body, "    - `{qualified_name}` -> `{alias}`").unwrap();
         }
     }