feat(fmt): add single_line_imports option to keep single imports on one line

crates/config/src/fmt.rs

@@ -42,6 +42,8 @@ pub struct FormatterConfig {
     /// Style that determines if a broken list, should keep its elements together on their own
     /// line, before breaking individually.
     pub prefer_compact: PreferCompact,
+    /// Keep single imports on a single line even if they exceed line length.
+    pub single_line_imports: bool,
 }
 
 /// Style of integer types.
@@ -251,6 +253,7 @@ impl Default for FormatterConfig {
             pow_no_space: false,
             prefer_compact: PreferCompact::default(),
             docs_style: DocCommentStyle::default(),
+            single_line_imports: false,
         }
     }
 }

crates/fmt/README.md

@@ -128,6 +128,7 @@ The formatter supports multiple configuration options defined in `foundry.toml`.
 | `contract_new_lines` | `false` | Add a new line at the start and end of contract declarations. |
 | `sort_imports` | `false` | Sort import statements alphabetically in groups. A group is a set of imports separated by a newline. |
 | `pow_no_space` | `false` | Suppress spaces around the power operator (`**`). |
+| `single_line_imports` | `false` | Keep single imports on a single line, even if they exceed the line length limit. |
 
 > Check [`FormatterConfig`](../config/src/fmt.rs) for a more detailed explanation.
 

crates/fmt/src/state/sol.rs

@@ -215,22 +215,34 @@ impl<'ast> State<'_, 'ast> {
             }
 
             ast::ImportItems::Aliases(aliases) => {
-                self.s.cbox(self.ind);
+                // Check if we should keep single imports on one line
+                let use_single_line = self.config.single_line_imports && aliases.len() == 1;
+
+                if !use_single_line {
+                    self.s.cbox(self.ind);
+                }
                 self.word("{");
-                self.braces_break();
+                if !use_single_line {
+                    self.braces_break();
+                }
 
-                if self.config.sort_imports {
+                let aliases_iter: Box<dyn Iterator<Item = _>> = if self.config.sort_imports {
                     let mut sorted: Vec<_> = aliases.iter().collect();
                     sorted.sort_by_key(|(ident, _alias)| ident.name.as_str());
-                    self.print_commasep_aliases(sorted.into_iter());
+                    Box::new(sorted.into_iter())
                 } else {
-                    self.print_commasep_aliases(aliases.iter());
+                    Box::new(aliases.iter())
                 };
+                self.print_commasep_aliases(aliases_iter);
 
-                self.braces_break();
-                self.s.offset(-self.ind);
+                if !use_single_line {
+                    self.braces_break();
+                    self.s.offset(-self.ind);
+                }
                 self.word("}");
-                self.end();
+                if !use_single_line {
+                    self.end();
+                }
                 self.word(" from ");
                 self.print_ast_str_lit(path);
             }

crates/fmt/testdata/SingleLineImports/fmt.sol

@@ -0,0 +1,30 @@
+// Test cases for single_line_imports configuration
+
+// Single import that exceeds line length (121 chars)
+import {
+    ITransparentUpgradeableProxy
+} from "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
+
+// Single import with trailing comment
+import {SomeContract} from "path/to/SomeContract.sol"; // This is a comment
+
+// Single import with comment above
+// This contract handles authentication
+import {AuthManager} from "contracts/auth/AuthManager.sol";
+
+// Multiple imports should still wrap regardless of config
+import {
+    Contract1,
+    Contract2,
+    Contract3,
+    Contract4
+} from "long/path/to/contracts.sol";
+
+// Short single import
+import {Token} from "Token.sol";
+
+// Single import with alias
+import {LongContractName as LCN} from "contracts/LongContractName.sol";
+
+// Mixed comment styles
+import {MixedComment} from "Mixed.sol"; /* block comment */ // line comment

crates/fmt/testdata/SingleLineImports/original.sol

@@ -0,0 +1,23 @@
+// Test cases for single_line_imports configuration
+
+// Single import that exceeds line length (121 chars)
+import { ITransparentUpgradeableProxy } from "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
+
+// Single import with trailing comment
+import { SomeContract } from "path/to/SomeContract.sol"; // This is a comment
+
+// Single import with comment above
+// This contract handles authentication
+import { AuthManager } from "contracts/auth/AuthManager.sol";
+
+// Multiple imports should still wrap regardless of config
+import { Contract1, Contract2, Contract3, Contract4 } from "long/path/to/contracts.sol";
+
+// Short single import
+import { Token } from "Token.sol";
+
+// Single import with alias
+import { LongContractName as LCN } from "contracts/LongContractName.sol";
+
+// Mixed comment styles
+import { MixedComment } from "Mixed.sol"; /* block comment */ // line comment

crates/fmt/testdata/SingleLineImports/single-line.fmt.sol

@@ -0,0 +1,29 @@
+// config: single_line_imports = true
+// Test cases for single_line_imports configuration
+
+// Single import that exceeds line length (121 chars)
+import {ITransparentUpgradeableProxy} from "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
+
+// Single import with trailing comment
+import {SomeContract} from "path/to/SomeContract.sol"; // This is a comment
+
+// Single import with comment above
+// This contract handles authentication
+import {AuthManager} from "contracts/auth/AuthManager.sol";
+
+// Multiple imports should still wrap regardless of config
+import {
+    Contract1,
+    Contract2,
+    Contract3,
+    Contract4
+} from "long/path/to/contracts.sol";
+
+// Short single import
+import {Token} from "Token.sol";
+
+// Single import with alias
+import {LongContractName as LCN} from "contracts/LongContractName.sol";
+
+// Mixed comment styles
+import {MixedComment} from "Mixed.sol"; /* block comment */ // line comment

crates/fmt/tests/formatter.rs

@@ -207,6 +207,7 @@ fmt_tests! {
     RevertNamedArgsStatement,
     RevertStatement,
     SimpleComments,
+    SingleLineImports,
     SortedImports,
     StatementBlock,
     StructDefinition,

crates/forge/tests/cli/config.rs

@@ -139,6 +139,7 @@ contract_new_lines = false
 sort_imports = false
 pow_no_space = false
 prefer_compact = "all"
+single_line_imports = false
 
 [lint]
 severity = []
@@ -1317,7 +1318,8 @@ forgetest_init!(test_default_config, |prj, cmd| {
     "contract_new_lines": false,
     "sort_imports": false,
     "pow_no_space": false,
-    "prefer_compact": "all"
+    "prefer_compact": "all",
+    "single_line_imports": false
   },
   "lint": {
     "severity": [],