Rollup merge of #102650 - Rageking8:slightly-improve-no-return-for-returning-function-error, r=compiler-errors

Slightly improve no return for returning function error

Fixes #100607

The rationale is that absolute beginners will be slightly confused as to why certain lines of code in a function does not require a semicolon. (I have actually witness a beginner having this confusion). Hence, a slight rationale is added "to return this value", which signals to the user that after removing said semicolon the value is returned resolving that error.

However, if this is not desirable, I welcome any other suggestions. Thanks.

12 files changed, 18 insertions, 19 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
index 7b1a2ad35cd..3618cfba533 100644
--- a/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
@@ -1123,7 +1123,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             } else {
                 err.span_suggestion_short(
                     span_semi,
-                    "remove this semicolon",
+                    "remove this semicolon to return this value",
                     "",
                     Applicability::MachineApplicable,
                 );
diff --git a/src/test/ui/block-result/consider-removing-last-semi.stderr b/src/test/ui/block-result/consider-removing-last-semi.stderr
index 2412dcd32f7..9be0367ae38 100644
--- a/src/test/ui/block-result/consider-removing-last-semi.stderr
+++ b/src/test/ui/block-result/consider-removing-last-semi.stderr
@@ -7,7 +7,7 @@ LL | pub fn f() -> String {
    |        implicitly returns `()` as its body has no tail or `return` expression
 LL |     0u8;
 LL |     "bla".to_string();
-   |                      - help: remove this semicolon
+   |                      - help: remove this semicolon to return this value
 
 error[E0308]: mismatched types
   --> $DIR/consider-removing-last-semi.rs:8:15
@@ -18,7 +18,7 @@ LL | pub fn g() -> String {
    |        implicitly returns `()` as its body has no tail or `return` expression
 LL |     "this won't work".to_string();
 LL |     "removeme".to_string();
-   |                           - help: remove this semicolon
+   |                           - help: remove this semicolon to return this value
 
 error[E0308]: mismatched types
   --> $DIR/consider-removing-last-semi.rs:13:25
@@ -29,7 +29,7 @@ LL | pub fn macro_tests() -> u32 {
    |        implicitly returns `()` as its body has no tail or `return` expression
 ...
 LL |     mac!();
-   |           - help: remove this semicolon
+   |           - help: remove this semicolon to return this value
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/block-result/issue-11714.stderr b/src/test/ui/block-result/issue-11714.stderr
index 5b8d96fd4eb..42fb3d3d43d 100644
--- a/src/test/ui/block-result/issue-11714.stderr
+++ b/src/test/ui/block-result/issue-11714.stderr
@@ -7,7 +7,7 @@ LL | fn blah() -> i32 {
    |    implicitly returns `()` as its body has no tail or `return` expression
 ...
 LL |     ;
-   |     - help: remove this semicolon
+   |     - help: remove this semicolon to return this value
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/block-result/issue-13428.stderr b/src/test/ui/block-result/issue-13428.stderr
index a33448edff2..2b386d10c53 100644
--- a/src/test/ui/block-result/issue-13428.stderr
+++ b/src/test/ui/block-result/issue-13428.stderr
@@ -15,7 +15,7 @@ LL | fn bar() -> String {
    |    implicitly returns `()` as its body has no tail or `return` expression
 LL |     "foobar".to_string()
 LL |     ;
-   |     - help: remove this semicolon
+   |     - help: remove this semicolon to return this value
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/closures/old-closure-expression-remove-semicolon.fixed b/src/test/ui/closures/old-closure-expression-remove-semicolon.fixed
index 623e917da07..8aa9e952b99 100644
--- a/src/test/ui/closures/old-closure-expression-remove-semicolon.fixed
+++ b/src/test/ui/closures/old-closure-expression-remove-semicolon.fixed
@@ -7,6 +7,6 @@ fn foo() -> i32 {
 fn main() {
     let _x: i32 = {
         //~^ ERROR mismatched types
-        foo() //~ HELP remove this semicolon
+        foo() //~ HELP remove this semicolon to return this value
     };
 }
diff --git a/src/test/ui/closures/old-closure-expression-remove-semicolon.rs b/src/test/ui/closures/old-closure-expression-remove-semicolon.rs
index 4974b086649..912c7a3314a 100644
--- a/src/test/ui/closures/old-closure-expression-remove-semicolon.rs
+++ b/src/test/ui/closures/old-closure-expression-remove-semicolon.rs
@@ -7,6 +7,6 @@ fn foo() -> i32 {
 fn main() {
     let _x: i32 = {
         //~^ ERROR mismatched types
-        foo(); //~ HELP remove this semicolon
+        foo(); //~ HELP remove this semicolon to return this value
     };
 }
diff --git a/src/test/ui/closures/old-closure-expression-remove-semicolon.stderr b/src/test/ui/closures/old-closure-expression-remove-semicolon.stderr
index 9b73ce4fee3..bc54ab4d511 100644
--- a/src/test/ui/closures/old-closure-expression-remove-semicolon.stderr
+++ b/src/test/ui/closures/old-closure-expression-remove-semicolon.stderr
@@ -5,7 +5,7 @@ LL |       let _x: i32 = {
    |  ___________________^
 LL | |
 LL | |         foo();
-   | |              - help: remove this semicolon
+   | |              - help: remove this semicolon to return this value
 LL | |     };
    | |_____^ expected `i32`, found `()`
 
diff --git a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
index a4843bca58c..4c04bb11351 100644
--- a/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
+++ b/src/test/ui/coercion/coercion-missing-tail-expected-type.stderr
@@ -6,7 +6,7 @@ LL | fn plus_one(x: i32) -> i32 {
    |    |
    |    implicitly returns `()` as its body has no tail or `return` expression
 LL |     x + 1;
-   |          - help: remove this semicolon
+   |          - help: remove this semicolon to return this value
 
 error[E0308]: mismatched types
   --> $DIR/coercion-missing-tail-expected-type.rs:8:13
@@ -16,7 +16,7 @@ LL | fn foo() -> Result<u8, u64> {
    |    |
    |    implicitly returns `()` as its body has no tail or `return` expression
 LL |     Ok(1);
-   |          - help: remove this semicolon
+   |          - help: remove this semicolon to return this value
    |
    = note:   expected enum `Result<u8, u64>`
            found unit type `()`
diff --git a/src/test/ui/issues/issue-6458-4.stderr b/src/test/ui/issues/issue-6458-4.stderr
index d6e74d10e03..168ececac31 100644
--- a/src/test/ui/issues/issue-6458-4.stderr
+++ b/src/test/ui/issues/issue-6458-4.stderr
@@ -6,7 +6,7 @@ LL | fn foo(b: bool) -> Result<bool,String> {
    |    |
    |    implicitly returns `()` as its body has no tail or `return` expression
 LL |     Err("bar".to_string());
-   |                           - help: remove this semicolon
+   |                           - help: remove this semicolon to return this value
    |
    = note:   expected enum `Result<bool, String>`
            found unit type `()`
diff --git a/src/test/ui/liveness/liveness-return-last-stmt-semi.rs b/src/test/ui/liveness/liveness-return-last-stmt-semi.rs
index e8909c4a5ae..dff859429c9 100644
--- a/src/test/ui/liveness/liveness-return-last-stmt-semi.rs
+++ b/src/test/ui/liveness/liveness-return-last-stmt-semi.rs
@@ -1,4 +1,3 @@
-//
 // regression test for #8005
 
 macro_rules! test { () => { fn foo() -> i32 { 1; } } }
diff --git a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
index 82d136bd318..de0843aa637 100644
--- a/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
+++ b/src/test/ui/liveness/liveness-return-last-stmt-semi.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:7:19
+  --> $DIR/liveness-return-last-stmt-semi.rs:6:19
    |
 LL | fn no_return() -> i32 {}
    |    ---------      ^^^ expected `i32`, found `()`
@@ -7,17 +7,17 @@ LL | fn no_return() -> i32 {}
    |    implicitly returns `()` as its body has no tail or `return` expression
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:9:19
+  --> $DIR/liveness-return-last-stmt-semi.rs:8:19
    |
 LL | fn bar(x: u32) -> u32 {
    |    ---            ^^^ expected `u32`, found `()`
    |    |
    |    implicitly returns `()` as its body has no tail or `return` expression
 LL |     x * 2;
-   |          - help: remove this semicolon
+   |          - help: remove this semicolon to return this value
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:13:19
+  --> $DIR/liveness-return-last-stmt-semi.rs:12:19
    |
 LL | fn baz(x: u64) -> u32 {
    |    ---            ^^^ expected `u32`, found `()`
@@ -25,7 +25,7 @@ LL | fn baz(x: u64) -> u32 {
    |    implicitly returns `()` as its body has no tail or `return` expression
 
 error[E0308]: mismatched types
-  --> $DIR/liveness-return-last-stmt-semi.rs:4:41
+  --> $DIR/liveness-return-last-stmt-semi.rs:3:41
    |
 LL | macro_rules! test { () => { fn foo() -> i32 { 1; } } }
    |                                ---      ^^^ expected `i32`, found `()`
diff --git a/src/test/ui/suggestions/match-with-different-arm-types-as-stmt-instead-of-expr.stderr b/src/test/ui/suggestions/match-with-different-arm-types-as-stmt-instead-of-expr.stderr
index be6fc261562..00aa7d18a96 100644
--- a/src/test/ui/suggestions/match-with-different-arm-types-as-stmt-instead-of-expr.stderr
+++ b/src/test/ui/suggestions/match-with-different-arm-types-as-stmt-instead-of-expr.stderr
@@ -7,7 +7,7 @@ LL | fn not_all_paths(a: &str) -> u32 {
    |    implicitly returns `()` as its body has no tail or `return` expression
 ...
 LL |     };
-   |      - help: remove this semicolon
+   |      - help: remove this semicolon to return this value
 
 error[E0308]: `match` arms have incompatible types
   --> $DIR/match-with-different-arm-types-as-stmt-instead-of-expr.rs:26:14