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make implicit cstring conversions explicit (#19488)

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The Nim manual says that an implicit conversion to cstring will
eventually not be allowed [1]:

    A Nim `string` is implicitly convertible to `cstring` for convenience.

    [...]

    Even though the conversion is implicit, it is not *safe*: The garbage collector
    does not consider a `cstring` to be a root and may collect the underlying
    memory. For this reason, the implicit conversion will be removed in future
    releases of the Nim compiler. Certain idioms like conversion of a `const` string
    to `cstring` are safe and will remain to be allowed.

And from Nim 1.6.0, such a conversion triggers a warning [2]:

    A dangerous implicit conversion to `cstring` now triggers a `[CStringConv]` warning.
    This warning will become an error in future versions! Use an explicit conversion
    like `cstring(x)` in order to silence the warning.

However, some files in this repo produced such a warning. For example,
before this commit, compiling `parsejson.nim` would produce:

    /foo/Nim/lib/pure/parsejson.nim(221, 37) Warning: implicit conversion to 'cstring' from a non-const location: my.buf; this will become a compile time error in the future [CStringConv]
    /foo/Nim/lib/pure/parsejson.nim(231, 39) Warning: implicit conversion to 'cstring' from a non-const location: my.buf; this will become a compile time error in the future [CStringConv]

This commit resolves the most visible `CStringConv` warnings, making the
cstring conversions explicit.

[1] https://github.com/nim-lang/Nim/blob/d2318d9ccfe6/doc/manual.md#cstring-type
[2] https://github.com/nim-lang/Nim/blob/d2318d9ccfe6/changelogs/changelog_1_6_0.md#type-system
This commit is contained in:
ee7
2022-08-19 21:40:53 +02:00
committed by ringabout
parent 14c6c1c695
commit 4010ad7229
1 changed files with 3 additions and 3 deletions
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6
src/db_sqlite.nim
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@@ -235,7 +235,7 @@ proc tryExec*(db: DbConn, query: SqlQuery,
assert(not db.isNil, "Database not connected.")
var q = dbFormat(query, args)
var stmt: sqlite3.PStmt
if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
if prepare_v2(db, q.cstring, q.len.cint, stmt, nil) == SQLITE_OK:
let x = step(stmt)
if x in {SQLITE_DONE, SQLITE_ROW}:
result = finalize(stmt) == SQLITE_OK
@@ -278,7 +278,7 @@ proc setupQuery(db: DbConn, query: SqlQuery,
args: varargs[string]): PStmt =
assert(not db.isNil, "Database not connected.")
var q = dbFormat(query, args)
if prepare_v2(db, q, q.len.cint, result, nil) != SQLITE_OK: dbError(db)
if prepare_v2(db, q.cstring, q.len.cint, result, nil) != SQLITE_OK: dbError(db)
proc setupQuery(db: DbConn, stmtName: SqlPrepared): SqlPrepared {.since: (1, 3).} =
assert(not db.isNil, "Database not connected.")
@@ -653,7 +653,7 @@ proc tryInsertID*(db: DbConn, query: SqlQuery,
var q = dbFormat(query, args)
var stmt: sqlite3.PStmt
result = -1
if prepare_v2(db, q, q.len.cint, stmt, nil) == SQLITE_OK:
if prepare_v2(db, q.cstring, q.len.cint, stmt, nil) == SQLITE_OK:
if step(stmt) == SQLITE_DONE:
result = last_insert_rowid(db)
if finalize(stmt) != SQLITE_OK: