[MacPorts] #72452: base: Detect safe pattern for implicit declarations

[MacPorts]

#72452: base: Detect safe pattern for implicit declarations
---------------------------+--------------------
  Reporter:  Dave-Allured  |      Owner:  (none)
      Type:  enhancement   |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  base          |    Version:
Resolution:                |   Keywords:
      Port:                |
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Description changed by ryandesign:

Old description:

> The documentation for
> [https://trac.macports.org/wiki/WimplicitFunctionDeclaration#AddnamestowhitelistviaPortfile
> Implicit Function Declaration:Add names to whitelist via Portfile]
> describes a case where the implicit declaration is a deliberate compiler
> test.  Warnings for these known cases should be suppressed.
>
> The current ignore method is to whitelist all occurrences of specified
> functions, during port configuration.  Here is a finer grained approach.
> These known cases follow a pattern which can be detected and
> automatically ignored.  I suggest this is safer than ignoring all
> occurrences.
>
> The basic idea is to pattern-recognize the known special test for "detect
> undeclared functions".  Based on my current debug problem, the pattern in
> `config.log` looks like this.  This would be an enhancement to the
> existing checks in `portconfigure::check_implicit_function_declarations`.
> Match exactly **three consecutive lines** with regex:
> {{{
> configure:.* checking for .* needed to detect all undeclared functions
> configure:.* conftest.c >
> conftest\.c:.* call to undeclared library function (NAME)
> }}}
> When this three-line pattern is detected, the implicit warning is then
> automatically IGNORED and not output as a warning to the user.  (NAME)
> might start out as simply `strchr`, maybe expanded later to a special
> short list of known test names.
>
> Benefits:
> * Reduced interactions for port maintainers.
> * Allow removal of port-specific whitelisted function names in many
> portfiles.
> * Increased safety, as I said above.

New description:

 The documentation for
 [wiki:WimplicitFunctionDeclaration#AddnamestowhitelistviaPortfile Implicit
 Function Declaration:Add names to whitelist via Portfile] describes a case
 where the implicit declaration is a deliberate compiler test.  Warnings
 for these known cases should be suppressed.

 The current ignore method is to whitelist all occurrences of specified
 functions, during port configuration.  Here is a finer grained approach.
 These known cases follow a pattern which can be detected and automatically
 ignored.  I suggest this is safer than ignoring all occurrences.

 The basic idea is to pattern-recognize the known special test for "detect
 undeclared functions".  Based on my current debug problem, the pattern in
 `config.log` looks like this.  This would be an enhancement to the
 existing checks in `portconfigure::check_implicit_function_declarations`.
 Match exactly **three consecutive lines** with regex:
 {{{
 configure:.* checking for .* needed to detect all undeclared functions
 configure:.* conftest.c >
 conftest\.c:.* call to undeclared library function (NAME)
 }}}
 When this three-line pattern is detected, the implicit warning is then
 automatically IGNORED and not output as a warning to the user.  (NAME)
 might start out as simply `strchr`, maybe expanded later to a special
 short list of known test names.

 Benefits:
 * Reduced interactions for port maintainers.
 * Allow removal of port-specific whitelisted function names in many
 portfiles.
 * Increased safety, as I said above.

--

-- 
Ticket URL: <https://trac.macports.org/ticket/72452#comment:1>
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