[PATCH] Add option to disable module loading.

[Doug Gregor]

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Comment at: include/clang/Basic/LangOptions.def:96
@@ -95,2 +95,3 @@
 LANGOPT(Modules           , 1, 0, "modules extension to C")
+LANGOPT(Modules_noload    , 1, 0, "disable loading of modules")
 LANGOPT(Optimize          , 1, 0, "__OPTIMIZE__ predefined macro")
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I'd rather have these options build constructively, rather than destructively, because it's hard to remember to check "Modules && !Modules_noload". I suggest you divide it as:

 - ModuleMaps: read module maps and use them to somehow understand the structure of library headers    
 - Modules: full support for modules, which implies ModuleMaps

Moreover, I think ModuleMaps belongs in HeaderSearchOptions, because it's really about the headers. In fact, one could imagine a future panacea where we have Modules && !ModuleMaps, because headers have become irrelevant :)

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Comment at: include/clang/Driver/Options.td:520
@@ -519,1 +519,3 @@
   HelpText<"Enable the 'modules' language feature">;
+def fmodules_noload : Flag <["-"], "fmodules-noload">, Group<f_Group>, Flags<[NoForward,CC1Option]>,
+  HelpText<"Disable the loading of 'modules'">;
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How about -fmodule-maps?

Also, it doesn't look like this is getting passed through the driver. Make sure you check whether "clang -fmodules-noload -###" passes -fmodules-noload through to the -cc1 invocation.

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Comment at: include/clang/Basic/DiagnosticCommonKinds.td:81
@@ -80,2 +80,3 @@
 def err_module_not_built : Error<"could not build module '%0'">, DefaultFatal;
+def err_module_load_off : Error<"module loading is off '%0'">, DefaultFatal;
 def err_module_cycle : Error<"cyclic dependency in module '%0': %1">, 
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I don't think we need this diagnostic; see below.


http://llvm-reviews.chandlerc.com/D963