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Optional warning for implicit constant conversion overflow

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This commit is contained in:
bbbradsmith 2023-05-02 22:27:28 -04:00
parent bf5b37a3b2
commit 409235aee6
4 changed files with 10 additions and 0 deletions
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2
doc/cc65.sgml
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@ -754,6 +754,8 @@ Here is a description of all the command line options:
Warn about unused function parameters.
<tag><tt/unused-var/</tag>
Warn about unused variables.
<tag><tt/const-overflow/</tag>
Warn if numerical constant conversion implies overflow. (Disabled by default.)
</descrip>
The full list of available warning names can be retrieved by using the

2
src/cc65/error.c
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@ -79,6 +79,7 @@ IntStack WarnUnusedLabel = INTSTACK(1); /* - unused labels */
IntStack WarnUnusedParam = INTSTACK(1); /* - unused parameters */
IntStack WarnUnusedVar = INTSTACK(1); /* - unused variables */
IntStack WarnUnusedFunc = INTSTACK(1); /* - unused functions */
IntStack WarnConstOverflow = INTSTACK(0); /* - overflow conversion of numerical constants */
/* Map the name of a warning to the intstack that holds its state */
typedef struct WarnMapEntry WarnMapEntry;
@ -102,6 +103,7 @@ static WarnMapEntry WarnMap[] = {
{ &WarnUnusedLabel, "unused-label" },
{ &WarnUnusedParam, "unused-param" },
{ &WarnUnusedVar, "unused-var" },
{ &WarnConstOverflow, "const-overflow" },
};
Collection DiagnosticStrBufs;

1
src/cc65/error.h
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@ -76,6 +76,7 @@ extern IntStack WarnUnusedLabel; /* - unused labels */
extern IntStack WarnUnusedParam; /* - unused parameters */
extern IntStack WarnUnusedVar; /* - unused variables */
extern IntStack WarnUnusedFunc; /* - unused functions */
extern IntStack WarnConstOverflow; /* - overflow conversion of numerical constants */
/* Forward */
struct StrBuf;

5
src/cc65/typeconv.c
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@ -128,6 +128,7 @@ static void DoConversion (ExprDesc* Expr, const Type* NewType)
** internally already represented by a long.
*/
if (NewBits <= OldBits) {
unsigned long OldVal = Expr->IVal;
/* Cut the value to the new size */
Expr->IVal &= (0xFFFFFFFFUL >> (32 - NewBits));
@ -139,6 +140,10 @@ static void DoConversion (ExprDesc* Expr, const Type* NewType)
Expr->IVal |= shl_l (~0UL, NewBits);
}
}
if ((OldVal != Expr->IVal) && IS_Get (&WarnConstOverflow)) {
Warning ("Implicit conversion of constant overflows %d-bit destination", NewBits);
}
}
/* Do the integer constant <-> absolute address conversion if necessary */