Implement macro meta-variable expression

1 files changed, 91 insertions, 73 deletions

diff --git a/src/test/ui/macros/rfc-3086-metavar-expr/syntax-errors.stderr b/src/test/ui/macros/rfc-3086-metavar-expr/syntax-errors.stderr
index dc8b7a668c4..0188938a30e 100644
--- a/src/test/ui/macros/rfc-3086-metavar-expr/syntax-errors.stderr
+++ b/src/test/ui/macros/rfc-3086-metavar-expr/syntax-errors.stderr
@@ -1,203 +1,209 @@
 error: expected identifier, found `$`
-  --> $DIR/syntax-errors.rs:16:33
+  --> $DIR/syntax-errors.rs:17:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ count($i) } };
    |                                 ^^^^^ - help: try removing `$`
 
 error: expected identifier, found `$`
-  --> $DIR/syntax-errors.rs:22:26
+  --> $DIR/syntax-errors.rs:23:26
    |
 LL |     ( $i:ident ) => { ${ count($i) } };
    |                          ^^^^^ - help: try removing `$`
 
 error: unexpected token: $
-  --> $DIR/syntax-errors.rs:52:8
+  --> $DIR/syntax-errors.rs:53:8
    |
 LL |     ( $$ $a:ident ) => {
    |        ^
 
 note: `$$` and meta-variable expressions are not allowed inside macro parameter definitions
-  --> $DIR/syntax-errors.rs:52:8
+  --> $DIR/syntax-errors.rs:53:8
    |
 LL |     ( $$ $a:ident ) => {
    |        ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:59:19
+  --> $DIR/syntax-errors.rs:60:19
    |
 LL |         ${count() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:59:19
+  --> $DIR/syntax-errors.rs:60:19
    |
 LL |         ${count() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:62:19
+  --> $DIR/syntax-errors.rs:63:19
    |
 LL |         ${count(i a b c)}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:62:19
+  --> $DIR/syntax-errors.rs:63:19
    |
 LL |         ${count(i a b c)}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:64:22
+  --> $DIR/syntax-errors.rs:65:22
    |
 LL |         ${count(i, 1 a b c)}
    |                      ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:64:22
+  --> $DIR/syntax-errors.rs:65:22
    |
 LL |         ${count(i, 1 a b c)}
    |                      ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:66:20
+  --> $DIR/syntax-errors.rs:67:20
    |
 LL |         ${count(i) a b c}
    |                    ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:66:20
+  --> $DIR/syntax-errors.rs:67:20
    |
 LL |         ${count(i) a b c}
    |                    ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:69:21
+  --> $DIR/syntax-errors.rs:70:21
    |
 LL |         ${ignore(i) a b c}
    |                     ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:69:21
+  --> $DIR/syntax-errors.rs:70:21
    |
 LL |         ${ignore(i) a b c}
    |                     ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:71:20
+  --> $DIR/syntax-errors.rs:72:20
    |
 LL |         ${ignore(i a b c)}
    |                    ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:71:20
+  --> $DIR/syntax-errors.rs:72:20
    |
 LL |         ${ignore(i a b c)}
    |                    ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:74:19
+  --> $DIR/syntax-errors.rs:75:19
    |
 LL |         ${index() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:74:19
+  --> $DIR/syntax-errors.rs:75:19
    |
 LL |         ${index() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:76:19
+  --> $DIR/syntax-errors.rs:77:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:76:19
+  --> $DIR/syntax-errors.rs:77:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:79:19
+  --> $DIR/syntax-errors.rs:80:19
    |
 LL |         ${index() a b c}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:79:19
+  --> $DIR/syntax-errors.rs:80:19
    |
 LL |         ${index() a b c}
    |                   ^
 
 error: unexpected token: a
-  --> $DIR/syntax-errors.rs:81:19
+  --> $DIR/syntax-errors.rs:82:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
    |
 note: meta-variable expression must not have trailing tokens
-  --> $DIR/syntax-errors.rs:81:19
+  --> $DIR/syntax-errors.rs:82:19
    |
 LL |         ${index(1 a b c)}
    |                   ^
 
 error: meta-variable expression depth must be a literal
-  --> $DIR/syntax-errors.rs:88:33
+  --> $DIR/syntax-errors.rs:89:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ index(IDX) } };
    |                                 ^^^^^
 
 error: unexpected token: {
-  --> $DIR/syntax-errors.rs:94:8
+  --> $DIR/syntax-errors.rs:95:8
    |
 LL |     ( ${ length() } ) => {
    |        ^^^^^^^^^^^^
 
 note: `$$` and meta-variable expressions are not allowed inside macro parameter definitions
-  --> $DIR/syntax-errors.rs:94:8
+  --> $DIR/syntax-errors.rs:95:8
    |
 LL |     ( ${ length() } ) => {
    |        ^^^^^^^^^^^^
 
 error: expected one of: `*`, `+`, or `?`
-  --> $DIR/syntax-errors.rs:94:8
+  --> $DIR/syntax-errors.rs:95:8
    |
 LL |     ( ${ length() } ) => {
    |        ^^^^^^^^^^^^
 
 error: expected identifier
-  --> $DIR/syntax-errors.rs:101:33
+  --> $DIR/syntax-errors.rs:102:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ ignore() } };
    |                                 ^^^^^^
 
 error: only unsuffixes integer literals are supported in meta-variable expressions
-  --> $DIR/syntax-errors.rs:107:33
+  --> $DIR/syntax-errors.rs:108:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ index(1u32) } };
    |                                 ^^^^^
 
 error: meta-variable expression parameter must be wrapped in parentheses
-  --> $DIR/syntax-errors.rs:113:33
+  --> $DIR/syntax-errors.rs:114:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ count{i} } };
    |                                 ^^^^^
 
 error: expected identifier
-  --> $DIR/syntax-errors.rs:119:31
+  --> $DIR/syntax-errors.rs:120:31
    |
 LL |     ( $( $i:ident ),* ) => { ${ {} } };
    |                               ^^^^^^
 
 error: unrecognized meta-variable expression
-  --> $DIR/syntax-errors.rs:125:33
+  --> $DIR/syntax-errors.rs:140:33
    |
 LL |     ( $( $i:ident ),* ) => { ${ aaaaaaaaaaaaaa(i) } };
    |                                 ^^^^^^^^^^^^^^ help: supported expressions are count, ignore, index and length
 
+error: `count` can not be placed inside the inner-most repetition
+  --> $DIR/syntax-errors.rs:12:24
+   |
+LL |     ( $i:ident ) => { ${ count(i) } };
+   |                        ^^^^^^^^^^^^
+
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:16:30
+  --> $DIR/syntax-errors.rs:17:30
    |
 LL |     ( $( $i:ident ),* ) => { ${ count($i) } };
    |                              ^ expected expression
@@ -208,7 +214,7 @@ LL |     curly__rhs_dollar__round!(a, b, c);
    = note: this error originates in the macro `curly__rhs_dollar__round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:22:23
+  --> $DIR/syntax-errors.rs:23:23
    |
 LL |     ( $i:ident ) => { ${ count($i) } };
    |                       ^ expected expression
@@ -219,13 +225,13 @@ LL |     curly__rhs_dollar__no_round!(a);
    = note: this error originates in the macro `curly__rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: variable 'i' is still repeating at this depth
-  --> $DIR/syntax-errors.rs:40:36
+  --> $DIR/syntax-errors.rs:41:36
    |
 LL |     ( $( $i:ident ),* ) => { count($i) };
    |                                    ^^
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:59:9
+  --> $DIR/syntax-errors.rs:60:9
    |
 LL |         ${count() a b c}
    |         ^ expected expression
@@ -236,29 +242,18 @@ LL |     extra_garbage_after_metavar!(a);
    = note: this error originates in the macro `extra_garbage_after_metavar` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:125:30
+  --> $DIR/syntax-errors.rs:89:30
    |
-LL |     ( $( $i:ident ),* ) => { ${ aaaaaaaaaaaaaa(i) } };
-   |                              ^ expected expression
-...
-LL |     unknown_metavar!(a);
-   |     ------------------- in this macro invocation
-   |
-   = note: this error originates in the macro `unknown_metavar` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:113:30
-   |
-LL |     ( $( $i:ident ),* ) => { ${ count{i} } };
+LL |     ( $( $i:ident ),* ) => { ${ index(IDX) } };
    |                              ^ expected expression
 ...
-LL |     metavar_without_parens!(a);
-   |     -------------------------- in this macro invocation
+LL |     metavar_depth_is_not_literal!(a);
+   |     -------------------------------- in this macro invocation
    |
-   = note: this error originates in the macro `metavar_without_parens` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `metavar_depth_is_not_literal` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:101:30
+  --> $DIR/syntax-errors.rs:102:30
    |
 LL |     ( $( $i:ident ),* ) => { ${ ignore() } };
    |                              ^ expected expression
@@ -269,40 +264,63 @@ LL |     metavar_token_without_ident!(a);
    = note: this error originates in the macro `metavar_token_without_ident` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:88:30
+  --> $DIR/syntax-errors.rs:108:30
    |
-LL |     ( $( $i:ident ),* ) => { ${ index(IDX) } };
+LL |     ( $( $i:ident ),* ) => { ${ index(1u32) } };
    |                              ^ expected expression
 ...
-LL |     metavar_depth_is_not_literal!(a);
-   |     -------------------------------- in this macro invocation
+LL |     metavar_with_literal_suffix!(a);
+   |     ------------------------------- in this macro invocation
    |
-   = note: this error originates in the macro `metavar_depth_is_not_literal` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `metavar_with_literal_suffix` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:107:30
+  --> $DIR/syntax-errors.rs:114:30
    |
-LL |     ( $( $i:ident ),* ) => { ${ index(1u32) } };
+LL |     ( $( $i:ident ),* ) => { ${ count{i} } };
    |                              ^ expected expression
 ...
-LL |     metavar_with_literal_suffix!(a);
-   |     ------------------------------- in this macro invocation
+LL |     metavar_without_parens!(a);
+   |     -------------------------- in this macro invocation
    |
-   = note: this error originates in the macro `metavar_with_literal_suffix` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `metavar_without_parens` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected expression, found `$`
-  --> $DIR/syntax-errors.rs:119:30
+  --> $DIR/syntax-errors.rs:120:30
    |
 LL |     ( $( $i:ident ),* ) => { ${ {} } };
    |                              ^ expected expression
 ...
-LL |     open_brackets_without_tokens!(a)
+LL |     open_brackets_without_tokens!(a);
    |     -------------------------------- in this macro invocation
    |
    = note: this error originates in the macro `open_brackets_without_tokens` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error: variable `foo` is not recognized in meta-variable expression
+  --> $DIR/syntax-errors.rs:127:17
+   |
+LL |         ${count(foo)}
+   |                 ^^^
+
+error: variable `bar` is not recognized in meta-variable expression
+  --> $DIR/syntax-errors.rs:134:18
+   |
+LL |         ${ignore(bar)}
+   |                  ^^^
+
+error: expected expression, found `$`
+  --> $DIR/syntax-errors.rs:140:30
+   |
+LL |     ( $( $i:ident ),* ) => { ${ aaaaaaaaaaaaaa(i) } };
+   |                              ^ expected expression
+...
+LL |     unknown_metavar!(a);
+   |     ------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `unknown_metavar` (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0425]: cannot find function `count` in this scope
-  --> $DIR/syntax-errors.rs:28:30
+  --> $DIR/syntax-errors.rs:29:30
    |
 LL |     ( $( $i:ident ),* ) => { count(i) };
    |                              ^^^^^ not found in this scope
@@ -313,7 +331,7 @@ LL |     no_curly__no_rhs_dollar__round!(a, b, c);
    = note: this error originates in the macro `no_curly__no_rhs_dollar__round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `i` in this scope
-  --> $DIR/syntax-errors.rs:28:36
+  --> $DIR/syntax-errors.rs:29:36
    |
 LL |     ( $( $i:ident ),* ) => { count(i) };
    |                                    ^ not found in this scope
@@ -324,7 +342,7 @@ LL |     no_curly__no_rhs_dollar__round!(a, b, c);
    = note: this error originates in the macro `no_curly__no_rhs_dollar__round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find function `count` in this scope
-  --> $DIR/syntax-errors.rs:34:23
+  --> $DIR/syntax-errors.rs:35:23
    |
 LL |     ( $i:ident ) => { count(i) };
    |                       ^^^^^ not found in this scope
@@ -335,7 +353,7 @@ LL |     no_curly__no_rhs_dollar__no_round!(a);
    = note: this error originates in the macro `no_curly__no_rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `i` in this scope
-  --> $DIR/syntax-errors.rs:34:29
+  --> $DIR/syntax-errors.rs:35:29
    |
 LL |     ( $i:ident ) => { count(i) };
    |                             ^ not found in this scope
@@ -346,7 +364,7 @@ LL |     no_curly__no_rhs_dollar__no_round!(a);
    = note: this error originates in the macro `no_curly__no_rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find function `count` in this scope
-  --> $DIR/syntax-errors.rs:45:23
+  --> $DIR/syntax-errors.rs:46:23
    |
 LL |     ( $i:ident ) => { count($i) };
    |                       ^^^^^ not found in this scope
@@ -357,11 +375,11 @@ LL |     no_curly__rhs_dollar__no_round!(a);
    = note: this error originates in the macro `no_curly__rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `a` in this scope
-  --> $DIR/syntax-errors.rs:138:37
+  --> $DIR/syntax-errors.rs:153:37
    |
 LL |     no_curly__rhs_dollar__no_round!(a);
    |                                     ^ not found in this scope
 
-error: aborting due to 37 previous errors
+error: aborting due to 40 previous errors
 
 For more information about this error, try `rustc --explain E0425`.