Merge #6376

6376: Avoid impls_fnonce to return true when the trait solving is ambiguous  r=flodiebold a=GrayJack

This PR should fix #6375 

This adds a variation of `method_resolution::implements_trait` called `method_resolution::implements_trait_unique`, that only returns true when the trait solving is unique, and also change `impls_fnonce` to use the later instead.

I also added a test just to be sure.

Co-authored-by: GrayJack <[email protected]>

2 files changed, 12 insertions, 0 deletions

diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index c6b4f5a00..ee115972b 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -115,6 +115,12 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="value_param callable">f</span><span class="punctuation">(</span><span class="punctuation">)</span>
 <span class="punctuation">}</span>
 
+<span class="keyword">fn</span> <span class="function declaration">foobar</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="keyword">impl</span> <span class="unresolved_reference">Copy</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">let</span> <span class="variable declaration">bar</span> <span class="operator">=</span> <span class="function">foobar</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
 <span class="macro">macro_rules!</span> <span class="macro declaration">def_fn</span> <span class="punctuation">{</span>
     <span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">}</span>
 <span class="punctuation">}</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index dd43f9dd9..5ea712cf5 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -89,6 +89,12 @@ fn baz<F: Fn() -> ()>(f: F) {
     f()
 }
 
+fn foobar() -> impl Copy {}
+
+fn foo() {
+    let bar = foobar();
+}
+
 macro_rules! def_fn {
     ($($tt:tt)*) => {$($tt)*}
 }