Improve invalid assignment error

src/test/ui/issues/issue-13407.rs

@@ -4,7 +4,7 @@ mod A {
 
 fn main() {
     A::C = 1;
-    //~^ ERROR: invalid left-hand side expression
+    //~^ ERROR: invalid left-hand side of assignment
     //~| ERROR: mismatched types
     //~| ERROR: struct `C` is private
 }

src/test/ui/issues/issue-13407.stderr

@@ -10,11 +10,13 @@ error[E0308]: mismatched types
 LL |     A::C = 1;
    |            ^ expected struct `A::C`, found integer
 
-error[E0070]: invalid left-hand side expression
+error[E0070]: invalid left-hand side of assignment
   --> $DIR/issue-13407.rs:6:5
    |
 LL |     A::C = 1;
-   |     ^^^^^^^^ left-hand of expression not valid
+   |     ----^^^^
+   |     |
+   |     cannot assign to this expression
 
 error: aborting due to 3 previous errors
 

src/test/ui/issues/issue-26093.rs

@@ -1,7 +1,9 @@
 macro_rules! not_a_place {
     ($thing:expr) => {
         $thing = 42;
-        //~^ ERROR invalid left-hand side expression
+        //~^ ERROR invalid left-hand side of assignment
+        $thing += 42;
+        //~^ ERROR invalid left-hand side of assignment
     }
 }
 

src/test/ui/issues/issue-26093.stderr

@@ -1,12 +1,28 @@
-error[E0070]: invalid left-hand side expression
+error[E0070]: invalid left-hand side of assignment
   --> $DIR/issue-26093.rs:3:9
    |
 LL |         $thing = 42;
-   |         ^^^^^^^^^^^ left-hand of expression not valid
+   |         ^^^^^^^^^^^
 ...
 LL |     not_a_place!(99);
-   |     ----------------- in this macro invocation
+   |     -----------------
+   |     |            |
+   |     |            cannot assign to this expression
+   |     in this macro invocation
 
-error: aborting due to previous error
+error[E0067]: invalid left-hand side of assignment
+  --> $DIR/issue-26093.rs:5:16
+   |
+LL |         $thing += 42;
+   |                ^^
+...
+LL |     not_a_place!(99);
+   |     -----------------
+   |     |            |
+   |     |            cannot assign to this expression
+   |     in this macro invocation
 
-For more information about this error, try `rustc --explain E0070`.
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0067, E0070.
+For more information about an error, try `rustc --explain E0067`.

src/test/ui/issues/issue-34334.rs

@@ -3,7 +3,7 @@ fn main () {
     //~^ ERROR expected one of `,` or `>`, found `=`
     //~| ERROR expected value, found struct `Vec`
     //~| ERROR mismatched types
-    //~| ERROR invalid left-hand side expression
+    //~| ERROR invalid left-hand side of assignment
     //~| ERROR expected expression, found reserved identifier `_`
     //~| ERROR expected expression, found reserved identifier `_`
     let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();

src/test/ui/issues/issue-34334.stderr

@@ -35,11 +35,13 @@ LL |     let sr: Vec<(u32, _, _) = vec![];
             found struct `std::vec::Vec<_>`
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
-error[E0070]: invalid left-hand side expression
+error[E0070]: invalid left-hand side of assignment
   --> $DIR/issue-34334.rs:2:13
    |
 LL |     let sr: Vec<(u32, _, _) = vec![];
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^ left-hand of expression not valid
+   |             ---------------^^^^^^^^^
+   |             |
+   |             cannot assign to this expression
 
 error[E0599]: no method named `iter` found for type `()` in the current scope
   --> $DIR/issue-34334.rs:9:36