https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80369
Bug ID: 80369
Summary: Warnings from preprocessor generated code not shown
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: adam.trhon at gmail dot com
Target Milestone: ---
Created attachment 41162
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41162&action=edit
Minimal example
The example in main.c (attached) contains a preprocessor macro that should
generate tautological-compare warning (with -Wall). But the warning is not
generated unless preprocessing and compilation are done in separate steps.
When compiled as:
gcc -Wall main.c
the warning about tautological compare is *not shown*. But when compiled as:
gcc -Wall -no-integrated-cpp main.c
or as:
gcc -Wall -E main.c -o main.i
gcc -Wall --preprocessed main.i
then this warning is printed:
main.c: In function ‘main’:
main.c:31:11: warning: self-comparison always evaluates to false
[-Wtautological-compare]
FOO
^
The issue was observed with:
gcc 6.2 for ARM built by OpenEmbedded
gcc 6.3 for x86_64 from Arch Linux
gcc 7.0 for x86_64 built from upstram git (commit ae4f1e0ee12)
