Add diagnostics for bad semicolons errors, closes #352 #362
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Thank you. I can confirm that the usefulness of the diagnostics have increased by pinpointing the offending tokens. The |
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@hsutter all requested changes applied. |
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This change introduce diagnostics when there is a semicolon at
the end of the function body:
```cpp
g: () = {};
```
Generates:
```
error: a compound function body shall not end with a semicolon (at ';')
```
And
```cpp
g: () = 42;;
```
Generates:
```
error: a short function syntax shall end with a single semicolon (at ';')
```
This change introduce diagnostics when there is a semicolon at
the end of the for..do loop body:
```cpp
for v* | all next log() do :(e) = {
foo();
bar*;
};
```
generates:
```
error: for..do loop body shall not end with a semicolon (at ';')
```
This change introduce diagnostics when there is a semicolon at
the end of the while loop body:
```cpp
i := 0;
while i* < container.size() next i++ {
std::cout << container[i] << std::endl;
};
```
generates:
```
error: while loop body shall not end with a semicolon (at ';')
```
This change introduce diagnostics when there is a double semicolon at the end of the short function body for unnamed function: ```cpp l2 := :() -> int = 24;; ``` Generates: ``` error: a short function syntax shall end with a single semicolon (at ';') ```
This change introduce diagnostics when there is a semicolon without statement ```cpp ; ``` Generates: ``` error: empty statement is not allowed - remove extra semicolon (at ';') ``` That also handles cases when there is double semicolon after a proper statemnt: ```cpp i := 0;; ``` Generates: ``` error: empty statement is not allowed - remove extra semicolon (at ';') ```
When done() is true last correct token and its position is printed.
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| @@ -4707,6 +4722,11 @@ class parser | |||
| ) | |||
| -> std::unique_ptr<statement_node> | |||
| { | |||
| if (!done() && curr().type() == lexeme::Semicolon) { | |||
| error("empty statement is not allowed - remove extra semicolon"); | |||
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I think this works, but just a note: Emitting an error here (not just returning null) could interfere with productions where statement is one alternative but where if it doesn't parse as a statement we would want to try other fallback production(s) instead. I don't think that actually happens today in the grammar though, so this should be okay.
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Basically, the scenario would be "is there any production where a statement could appear, where if it's not a statement something else that starts with a ; could appear instead" -- I think there isn't today so it should be safe to reject a ; if we're in a position where a statement could appear
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Dec 5, 2023
…r#362) * Add diagnostics for semicolon at the end of function This change introduce diagnostics when there is a semicolon at the end of the function body: ```cpp g: () = {}; ``` Generates: ``` error: a compound function body shall not end with a semicolon (at ';') ``` And ```cpp g: () = 42;; ``` Generates: ``` error: a short function syntax shall end with a single semicolon (at ';') ``` * Add diagnostics for semicolon at the end of for loop This change introduce diagnostics when there is a semicolon at the end of the for..do loop body: ```cpp for v* | all next log() do :(e) = { foo(); bar*; }; ``` generates: ``` error: for..do loop body shall not end with a semicolon (at ';') ``` * Add diagnostics for semicolon at the end of while body This change introduce diagnostics when there is a semicolon at the end of the while loop body: ```cpp i := 0; while i* < container.size() next i++ { std::cout << container[i] << std::endl; }; ``` generates: ``` error: while loop body shall not end with a semicolon (at ';') ``` * Add diagnostics for double semicolon at short lambda This change introduce diagnostics when there is a double semicolon at the end of the short function body for unnamed function: ```cpp l2 := :() -> int = 24;; ``` Generates: ``` error: a short function syntax shall end with a single semicolon (at ';') ``` * Add diagnostics for empty statements (extra semicolon) This change introduce diagnostics when there is a semicolon without statement ```cpp ; ``` Generates: ``` error: empty statement is not allowed - remove extra semicolon (at ';') ``` That also handles cases when there is double semicolon after a proper statemnt: ```cpp i := 0;; ``` Generates: ``` error: empty statement is not allowed - remove extra semicolon (at ';') ``` * Fix error() method that throws when done() is true When done() is true last correct token and its position is printed.
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The current cppfront (f83ca9) implementation provides unclear error messages - it is hard to find what causes the error.
This change introduces diagnostics for:
f: () = {}; // error: a compound function body shall not end with a semicolon (at ';') g: () -> int = 42;; // error: a short function syntax shall end with a single semicolon (at ';') for v* | all next log() do :(e) = { foo(); bar*; }; // error: for..do loop body shall not end with a semicolon (at ';') i := 0; while i* < container.size() next i++ { std::cout << container[i] << std::endl; }; // error: while loop body shall not end with a semicolon (at ';') l2 := :() -> int = 24;; // error: a short function syntax shall end with a single semicolon (at ';') ; // error: empty statement is not allowed - remove extra semicolon (at ';') i := 0;; // error: empty statement is not allowed - remove extra semicolon (at ';')All regression tests pass. Closes #352