Sema: add notes about function return type

test/cases/compile_errors/address_of_number_literal.zig

@@ -9,3 +9,4 @@ export fn entry() usize { return @sizeOf(@TypeOf(&foo)); }
 //
 // :3:30: error: expected type '*const i32', found '*const comptime_int'
 // :3:30: note: pointer type child 'comptime_int' cannot cast into pointer type child 'i32'
+// :3:10: note: function return type declared here

test/cases/compile_errors/incompatible_sentinels.zig

@@ -21,8 +21,10 @@ export fn entry4() void {
 //
 // :4:12: error: expected type '[*:0]u8', found '[*:255]u8'
 // :4:12: note: pointer sentinel '255' cannot cast into pointer sentinel '0'
+// :3:35: note: function return type declared here
 // :7:12: error: expected type '[*:0]u8', found '[*]u8'
 // :7:12: note: destination pointer requires '0' sentinel
+// :6:31: note: function return type declared here
 // :10:35: error: expected type '[2:0]u8', found '[2:255]u8'
 // :10:35: note: array sentinel '255' cannot cast into array sentinel '0'
 // :14:31: error: expected type '[2:0]u8', found '[2]u8'

test/cases/compile_errors/incorrect_return_type.zig

@@ -21,3 +21,4 @@
 // :8:16: error: expected type 'tmp.A', found 'tmp.B'
 // :10:12: note: struct declared here
 // :4:12: note: struct declared here
+// :7:11: note: function return type declared here

test/cases/compile_errors/invalid_address_space_coercion.zig

@@ -12,3 +12,4 @@ pub fn main() void {
 //
 // :2:12: error: expected type '*i32', found '*addrspace(.gs) i32'
 // :2:12: note: address space 'gs' cannot cast into address space 'generic'
+// :1:34: note: function return type declared here

test/cases/compile_errors/invalid_pointer_keeps_address_space_when_taking_address_of_dereference.zig

@@ -12,3 +12,4 @@ pub fn main() void {
 //
 // :2:12: error: expected type '*i32', found '*addrspace(.gs) i32'
 // :2:12: note: address space 'gs' cannot cast into address space 'generic'
+// :1:34: note: function return type declared here

test/cases/compile_errors/pointer_with_different_address_spaces.zig

@@ -12,3 +12,4 @@ export fn entry2() void {
 //
 // :2:12: error: expected type '*addrspace(.fs) i32', found '*addrspace(.gs) i32'
 // :2:12: note: address space 'gs' cannot cast into address space 'fs'
+// :1:34: note: function return type declared here

test/cases/compile_errors/pointers_with_different_address_spaces.zig

@@ -12,3 +12,4 @@ pub fn main() void {
 //
 // :2:13: error: expected type '*i32', found '*addrspace(.gs) i32'
 // :2:13: note: address space 'gs' cannot cast into address space 'generic'
+// :1:35: note: function return type declared here

test/cases/compile_errors/slice_sentinel_mismatch-2.zig

@@ -10,3 +10,4 @@ comptime { _ = foo; }
 //
 // :3:12: error: expected type '[:0]u8', found '[]u8'
 // :3:12: note: destination pointer requires '0' sentinel
+// :1:10: note: function return type declared here

test/cases/compile_errors/stage1/test/helpful_return_type_error_message.zig

@@ -16,15 +16,17 @@ export fn quux() u32 {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
-// is_test=1
 //
-// tmp.zig:2:17: error: expected type 'u32', found 'error{Ohno}'
-// tmp.zig:1:17: note: function cannot return an error
-// tmp.zig:8:5: error: expected type 'void', found '@typeInfo(@typeInfo(@TypeOf(bar)).Fn.return_type.?).ErrorUnion.error_set'
-// tmp.zig:7:17: note: function cannot return an error
-// tmp.zig:11:15: error: cannot convert error union to payload type. consider using `try`, `catch`, or `if`. expected type 'u32', found '@typeInfo(@typeInfo(@TypeOf(bar)).Fn.return_type.?).ErrorUnion.error_set!u32'
-// tmp.zig:10:17: note: function cannot return an error
-// tmp.zig:15:14: error: cannot convert error union to payload type. consider using `try`, `catch`, or `if`. expected type 'u32', found '@typeInfo(@typeInfo(@TypeOf(bar)).Fn.return_type.?).ErrorUnion.error_set!u32'
-// tmp.zig:14:5: note: cannot store an error in type 'u32'
+// :2:18: error: expected type 'u32', found 'error{Ohno}'
+// :1:17: note: function cannot return an error
+// :8:5: error: expected type 'void', found '@typeInfo(@typeInfo(@TypeOf(tmp.bar)).Fn.return_type.?).ErrorUnion.error_set'
+// :7:17: note: function cannot return an error
+// :11:15: error: expected type 'u32', found '@typeInfo(@typeInfo(@TypeOf(tmp.bar)).Fn.return_type.?).ErrorUnion.error_set!u32'
+// :10:17: note: function cannot return an error
+// :11:15: note: cannot convert error union to payload type
+// :11:15: note: consider using `try`, `catch`, or `if`
+// :15:14: error: expected type 'u32', found '@typeInfo(@typeInfo(@TypeOf(tmp.bar)).Fn.return_type.?).ErrorUnion.error_set!u32'
+// :15:14: note: cannot convert error union to payload type
+// :15:14: note: consider using `try`, `catch`, or `if`

test/cases/compile_errors/try_in_function_with_non_error_return_type.zig

@@ -8,3 +8,4 @@ fn something() anyerror!void { }
 // target=native
 //
 // :2:5: error: expected type 'void', found 'anyerror'
+// :1:15: note: function cannot return an error

test/cases/compile_errors/unreachable_with_return.zig

@@ -5,4 +5,5 @@ export fn entry() void { a(); }
 // backend=stage2
 // target=native
 //
-// :1:18: error: expected type 'noreturn', found 'void'
+// :1:18: error: function declared 'noreturn' returns
+// :1:8: note: 'noreturn' declared here

test/cases/compile_errors/variable_has_wrong_type.zig

@@ -8,3 +8,4 @@ export fn f() i32 {
 // target=native
 //
 // :3:12: error: expected type 'i32', found '*const [1:0]u8'
+// :1:15: note: function return type declared here