fix(compiler): improve error diagnostic for invalid string concat (#7025

) Co-authored-by: wingbot <[email protected]> Co-authored-by: monada-bot[bot] <[email protected]>
winglang · Aug 19, 2024 · 75ca07a · 75ca07a
1 parent 1dc08f5
commit 75ca07a
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Showing 3 changed files with 56 additions and 9 deletions.
diff --git a/examples/tests/invalid/stringify.test.w b/examples/tests/invalid/stringify.test.w
@@ -19,3 +19,11 @@ log(b);
 
 log(foo);
 // ^ Expected type to be "stringable", but got "Foo" instead
+
+let z = 42;
+
+log("value: " + z);
+// ^ Binary operator '+' cannot be applied to operands of type 'str' and 'num'
+
+log(z + " is the value");
+// ^ Binary operator '+' cannot be applied to operands of type 'str' and 'num'
diff --git a/libs/wingc/src/type_check.rs b/libs/wingc/src/type_check.rs
@@ -2296,17 +2296,24 @@ It should primarily be used in preflight or in inflights that are guaranteed to
 				} else {
 					// If any of the types are unresolved (error) then don't report this assuming the error has already been reported
 					if !ltype.is_unresolved() && !rtype.is_unresolved() {
-						self.spanned_error(
+						let mut hints = vec![];
+						// If one of the operands is a string type, add a hint to use string interpolation
+						if ltype.is_subtype_of(&self.types.string()) || rtype.is_subtype_of(&self.types.string()) {
+							hints.push("Consider using string interpolation: \"Hello, {name}\"".to_string());
+						}
+
+						self.spanned_error_with_hints(
 							exp,
 							format!(
-														"Binary operator '+' cannot be applied to operands of type '{}' and '{}'; only ({}, {}) and ({}, {}) are supported",
-														ltype,
-														rtype,
-														self.types.number(),
-														self.types.number(),
-														self.types.string(),
-														self.types.string(),
-													),
+								"Binary operator '+' cannot be applied to operands of type '{}' and '{}'; only ({}, {}) and ({}, {}) are supported",
+								ltype,
+								rtype,
+								self.types.number(),
+								self.types.number(),
+								self.types.string(),
+								self.types.string(),
+							),
+							&hints,
 						);
 					}
 					self.resolved_error()

diff --git a/tools/hangar/__snapshots__/invalid.ts.snap b/tools/hangar/__snapshots__/invalid.ts.snap
@@ -988,6 +988,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
     |
 185 |     2 + "2";
     |     ^^^^^^^
+    |
+    = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Expected type to be "num", but got "str" instead
@@ -1002,6 +1004,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
     |
 198 |     2 + "2";
     |     ^^^^^^^
+    |
+    = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Expected type to be "str", but got "num" instead
@@ -1016,6 +1020,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
     |
 210 |     2 + "2";
     |     ^^^^^^^
+    |
+    = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Expected type to be "num", but got "str" instead
@@ -1030,6 +1036,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
     |
 221 |     2 + "2";
     |     ^^^^^^^
+    |
+    = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Expected type to be "str", but got "num" instead
@@ -2307,6 +2315,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
    |
 36 | let var x = 3 + "hello";
    |             ^^^^^^^^^^^
+   |
+   = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Unsupported reassignment of element of type unresolved
@@ -4629,6 +4639,24 @@ error: Expected type to be "stringable", but got "Foo" instead
    |
    = hint: str, num, bool, json, and enums are stringable
 
+
+error: Binary operator '+' cannot be applied to operands of type 'str' and 'num'; only (num, num) and (str, str) are supported
+   --> ../../../examples/tests/invalid/stringify.test.w:25:5
+   |
+25 | log("value: " + z);
+   |     ^^^^^^^^^^^^^
+   |
+   = hint: Consider using string interpolation: "Hello, {name}"
+
+
+error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'; only (num, num) and (str, str) are supported
+   --> ../../../examples/tests/invalid/stringify.test.w:28:5
+   |
+28 | log(z + " is the value");
+   |     ^^^^^^^^^^^^^^^^^^^
+   |
+   = hint: Consider using string interpolation: "Hello, {name}"
+
 Tests 1 failed (1)
 Snapshots 1 skipped
 Test Files 1 failed (1)
@@ -4974,6 +5002,8 @@ exports[`types_strings_arithmetic.test.w 1`] = `
   |
 1 | let e1 = 2 + "2";
   |          ^^^^^^^
+  |
+  = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Expected type to be "num", but got "str" instead
@@ -5188,6 +5218,8 @@ error: Binary operator '+' cannot be applied to operands of type 'num' and 'str'
    |
 20 |     this.bucket.assert(2 + "2");
    |                        ^^^^^^^
+   |
+   = hint: Consider using string interpolation: "Hello, {name}"
 
 
 error: Member "assert" does not exist in "Bucket"