0002001: Zero output after preprocessing on cc17 -E

ID	Project	Category	View Status	Date Submitted	Last Update

0002001	1003.1(2024)/Issue8	Shell and Utilities	public	2026-10-20 00:03	2026-11-04 14:50

Reporter	Love4Bobbies	Assigned To	msbrown
Priority	normal	Severity	Editorial	Type	Error
Status	Interpretation Required	Resolution	Accepted As Marked

Name	Bogdan Barbu
Organization
User Reference
Section	c17
Page Number	https://pubs.opengroup.org/onlinepubs/9799919799/utilities/c17.html
Line Number	STDOUT section
Interp Status	Proposed
Final Accepted Text	0002001:0007541


Summary	0002001: Zero output after preprocessing on cc17 -E
Description	The -E compiler option POSIX's answer to dependency generation for make, as also explained in the rationale. This report has to do with the description of the -E option in the STDOUT section which is already being amended as per bug report 1925. That amendment does not introduce the issue I am describing here, it inherited it from the current standard, but I thought it was worth pointing out since we have two reports on the same text. With that correction in place, the wording would be as follows: --- If the -E option is specified, the standard output shall be a text file that represents the results of the preprocessing stage of the language; it may contain extra information appropriate for subsequent compilation passes and shall contain at least one line with the format: "# %d \"%s\"\n", <line>, <pathname> or "# %d \"%s\" %s\n", <line>, <pathname>, <flags> for each file processed as a result of a #include directive, unless no other output generated from that file is present in the output, where line is a line number, pathname is the pathname used to open the file, and flags is an implementation-defined string. --- The issue is with the wording "unless no other output generated from that file is present in the output." My reading of this is that if after preprocessing an included header does not output any tokens then -E should ignore it. Consider however the following example: // foo.h #define FOO 42 // foo.c #include "foo.h" The header produces no output after preprocessing and thus -E will ignore it when used in the process of generating a list of dependencies. Thus foo.h is essentially untracked so if we changed the definition of FOO, a makefile based on the generated dependency list would not know to recompile foo.c
Desired Action	The bit about headers not producing any headers should simply be stripped unless there is some good reason to keep it there which I am missing.
Tags	issue8

Love4Bobbies 2026-10-20 00:06 reporter bugnote:0007532	Sorry, I meant to write"the bit about headers not producing any OUTPUT" in the Desired Action field.

msbrown 2026-11-02 16:28 manager bugnote:0007541	Interpretation response ------------------------ The standard states the output format for c17 -E, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor. Rationale: ------------- None. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- On page 2673, lines 88036-88037, after applying 0001925, delete the phrase unless no other output generated from that file is present in the output,

agadmin 2026-11-04 14:50 administrator bugnote:0007543	Interpretation Proposed: November 4 2026

Date Modified	Username	Field	Change
2026-10-20 00:03	Love4Bobbies	New Issue
2026-10-20 00:06	Love4Bobbies	Note Added: 0007532
2026-11-02 16:00	nick	Relationship added	related to 0001925
2026-11-02 16:28	msbrown	Assigned To	=> msbrown
2026-11-02 16:28	msbrown	Status	New => Interpretation Required
2026-11-02 16:28	msbrown	Resolution	Open => Accepted As Marked
2026-11-02 16:28	msbrown	Interp Status	=> Proposed
2026-11-02 16:28	msbrown	Note Added: 0007541
2026-11-02 16:28	msbrown	Tag Attached: issue8
2026-11-04 14:50	agadmin	Final Accepted Text	=> 0002001:0007541
2026-11-04 14:50	agadmin	Note Added: 0007543

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