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Error in initialization within YY_INITIAL_VALUE() with C++ #442

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matz opened this issue Jun 10, 2024 · 1 comment · Fixed by #443 or #465
Closed

Error in initialization within YY_INITIAL_VALUE() with C++ #442

matz opened this issue Jun 10, 2024 · 1 comment · Fixed by #443 or #465
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@matz
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matz commented Jun 10, 2024

In the generated C file, we see YY_INITIAL_VALUE (static YYSTYPE yyval_default;), but clang raises error error: default initialization of an object of const type. According to the C++ language specification, we need a user provided default constructor for this kind of declaration.

Changing the above line to 'YY_INITIAL_VALUE (static YYSTYPE yyval_default;)' as Bison 3.8.2 shows no error.
ydah added a commit to ydah/lrama that referenced this issue Jun 11, 2024
@ydah
Fix an error for initialization within YY_INITIAL_VALUE() with C++
be9b052 
Fix: ruby#442

Before:
```
❯ exe/lrama -d sample/calc.y -o calc.c && cc -Wall calc.c -o calc

❯ exe/lrama -d sample/calc.y -o calc.c && gcc -Wall calc.c -o calc

❯ exe/lrama -d sample/calc.y -o calc.c && c++ -Wall calc.c -o calc
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
calc.c:1199:40: error: default initialization of an object of const type 'const YYSTYPE' without a user-provided default constructor
YY_INITIAL_VALUE (static const YYSTYPE yyval_default;)
```

After:
```
❯ exe/lrama -d sample/calc.y -o calc.c && cc -Wall calc.c -o calc

❯ exe/lrama -d sample/calc.y -o calc.c && gcc -Wall calc.c -o calc

❯ exe/lrama -d sample/calc.y -o calc.c && c++ -Wall calc.c -o calc
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
```
@ydah ydah mentioned this issue Jun 11, 2024
Merged
@ydah ydah closed this as completed in #443 Jun 17, 2024
matz added a commit to mruby/mruby that referenced this issue Jun 21, 2024
@matz
tools/lrama: apply ruby/lrama#442
fb9fbc8
@matz
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matz commented Jun 22, 2024

Unfortunately

static const YYSTYPE yyval_default = YY_INITIAL_VALUE(YYSTYPE());

causes compilation error when #define YY_INITIAL_VALUE(Value) /* Nothing. */

error: expected primary-expression before ‘;’ token
 6396 | static const YYSTYPE yyval_default = YY_INITIAL_VALUE(YYSTYPE());
      |                                                                 ^

@matz matz reopened this Jun 22, 2024
matz added a commit to mruby/mruby that referenced this issue Jun 22, 2024
@matz
Revert "tools/lrama: apply ruby/lrama#442"
54e9919 
This reverts commit fb9fbc8.

The fix in the upstream still causes syntax error in C++.
@ydah ydah added the bug Something isn't working label Jun 27, 2024
@ydah ydah mentioned this issue Aug 9, 2024
Merged
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