https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97602
Bug ID: 97602
Summary: #line overflow check incomplete
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: accepts-invalid
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: jsm28 at gcc dot gnu.org
Target Milestone: ---
Preprocessing the following test with -pedantic does not produce a diagnostic,
just silent wrapping of the line number.
#line 5000000000
By comparison, if you instead have
#line 3000000000
then you get a diagnostic
t.c:1:7: warning: line number out of range
1 | #line 3000000000
| ^~~~~~~~~~
The code in directives.c:strtolinenum tries to check for overflow after it
occurs, with logic "if (reg < reg_prev)" that doesn't cover all cases.
Checking before it occurs (allowing properly for the case of UINT_MAX / 10
where overflow depends on the value of the next digit) is needed instead.
