Do not deduplicate diagnostics in UI tests by default

tests/compile-test.rs

@@ -138,6 +138,7 @@ fn base_config(test_dir: &str) -> (Config, Args) {
             "-Aunused",
             "-Ainternal_features",
             "-Zui-testing",
+            "-Zdeduplicate-diagnostics=no",
             "-Dwarnings",
             &format!("-Ldependency={}", deps_path.display()),
         ]

tests/ui-internal/custom_ice_message.stderr

@@ -8,7 +8,7 @@ note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy
 
 note: rustc <version> running on <target>
 
-note: compiler flags: -Z ui-testing
+note: compiler flags: -Z ui-testing -Z deduplicate-diagnostics=no
 
 note: Clippy version: foo
 

tests/ui/assign_ops2.rs

@@ -1,4 +1,6 @@
 //@no-rustfix: overlapping suggestions
+//@compile-flags: -Zdeduplicate-diagnostics=yes
+
 #![allow(clippy::uninlined_format_args)]
 
 #[allow(unused_assignments)]

tests/ui/assign_ops2.stderr

@@ -1,5 +1,5 @@
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:8:5
+  --> tests/ui/assign_ops2.rs:10:5
    |
 LL |     a += a + 1;
    |     ^^^^^^^^^^
@@ -16,7 +16,7 @@ LL |     a = a + a + 1;
    |     ~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:11:5
+  --> tests/ui/assign_ops2.rs:13:5
    |
 LL |     a += 1 + a;
    |     ^^^^^^^^^^
@@ -31,7 +31,7 @@ LL |     a = a + 1 + a;
    |     ~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:13:5
+  --> tests/ui/assign_ops2.rs:15:5
    |
 LL |     a -= a - 1;
    |     ^^^^^^^^^^
@@ -46,7 +46,7 @@ LL |     a = a - (a - 1);
    |     ~~~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:15:5
+  --> tests/ui/assign_ops2.rs:17:5
    |
 LL |     a *= a * 99;
    |     ^^^^^^^^^^^
@@ -61,7 +61,7 @@ LL |     a = a * a * 99;
    |     ~~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:17:5
+  --> tests/ui/assign_ops2.rs:19:5
    |
 LL |     a *= 42 * a;
    |     ^^^^^^^^^^^
@@ -76,7 +76,7 @@ LL |     a = a * 42 * a;
    |     ~~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:19:5
+  --> tests/ui/assign_ops2.rs:21:5
    |
 LL |     a /= a / 2;
    |     ^^^^^^^^^^
@@ -91,7 +91,7 @@ LL |     a = a / (a / 2);
    |     ~~~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:21:5
+  --> tests/ui/assign_ops2.rs:23:5
    |
 LL |     a %= a % 5;
    |     ^^^^^^^^^^
@@ -106,7 +106,7 @@ LL |     a = a % (a % 5);
    |     ~~~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:23:5
+  --> tests/ui/assign_ops2.rs:25:5
    |
 LL |     a &= a & 1;
    |     ^^^^^^^^^^
@@ -121,7 +121,7 @@ LL |     a = a & a & 1;
    |     ~~~~~~~~~~~~~
 
 error: variable appears on both sides of an assignment operation
-  --> tests/ui/assign_ops2.rs:25:5
+  --> tests/ui/assign_ops2.rs:27:5
    |
 LL |     a *= a * a;
    |     ^^^^^^^^^^
@@ -136,7 +136,7 @@ LL |     a = a * a * a;
    |     ~~~~~~~~~~~~~
 
 error: manual implementation of an assign operation
-  --> tests/ui/assign_ops2.rs:63:5
+  --> tests/ui/assign_ops2.rs:65:5
    |
 LL |     buf = buf + cows.clone();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `buf += cows.clone()`

tests/ui/else_if_without_else.rs

@@ -1,3 +1,5 @@
+//@compile-flags: -Zdeduplicate-diagnostics=yes
+
 #![warn(clippy::all)]
 #![warn(clippy::else_if_without_else)]
 

tests/ui/else_if_without_else.stderr

@@ -1,5 +1,5 @@
 error: `if` expression with an `else if`, but without a final `else`
-  --> tests/ui/else_if_without_else.rs:45:12
+  --> tests/ui/else_if_without_else.rs:47:12
    |
 LL |       } else if bla2() {
    |  ____________^
@@ -13,7 +13,7 @@ LL | |     }
    = help: to override `-D warnings` add `#[allow(clippy::else_if_without_else)]`
 
 error: `if` expression with an `else if`, but without a final `else`
-  --> tests/ui/else_if_without_else.rs:54:12
+  --> tests/ui/else_if_without_else.rs:56:12
    |
 LL |       } else if bla3() {
    |  ____________^

tests/ui/identity_op.fixed

@@ -1,3 +1,5 @@
+//@compile-flags: -Zdeduplicate-diagnostics=yes
+
 #![warn(clippy::identity_op)]
 #![allow(unused)]
 #![allow(
@@ -134,7 +136,7 @@ fn main() {
     //~^ ERROR: this operation has no effect
     f(if b { 1 } else { 2 } + 3);
     //~^ ERROR: this operation has no effect
-    
+
     const _: i32 = { 2 * 4 } + 3;
     //~^ ERROR: this operation has no effect
     const _: i32 = { 1 + 2 * 3 } + 3;

tests/ui/identity_op.rs

@@ -1,3 +1,5 @@
+//@compile-flags: -Zdeduplicate-diagnostics=yes
+
 #![warn(clippy::identity_op)]
 #![allow(unused)]
 #![allow(
@@ -134,7 +136,7 @@ fn main() {
     //~^ ERROR: this operation has no effect
     f(0 + if b { 1 } else { 2 } + 3);
     //~^ ERROR: this operation has no effect
-    
+
     const _: i32 = { 2 * 4 } + 0 + 3;
     //~^ ERROR: this operation has no effect
     const _: i32 = 0 + { 1 + 2 * 3 } + 3;