Added a new c++-template-depth Boost Build feature allowing configuring compilers supporting this feature with the maximal template instantiation depth. Currently supported for gcc & qcc toolsets.

[SVN r47727]

doc/src/reference.xml

@@ -769,6 +769,32 @@ path-constant DATA : data/a.txt ;
         </listitem>
       </varlistentry>
 
+      <varlistentry><term><literal>c++-template-depth</literal></term>
+        <indexterm><primary>64-bit compilation</primary></indexterm>
+        <listitem>
+          <para>
+            <emphasis role="bold">Allowed values:</emphasis> Any positive
+            integer.
+          </para>
+
+          <para>
+            This feature allows configuring a C++ compiler with the maximal
+            template instantiation depth parameter. Exact default values as well
+            as whether this feature is supported at all depend on the toolset
+            used.
+          </para>
+
+          <para>
+            <emphasis role="bold">Note:</emphasis> Due to some internal details
+            in the current Boost Build implementation it is not possible to have
+            features whose valid values are all positive integer. As a
+            workaround a large set of allowed values has been defined for this
+            feature and, if a different one is needed, user can easily add it by
+            calling the feature.extend rule.
+          </para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
   </section>
 

src/tools/builtin.jam

@@ -15,6 +15,7 @@ import toolset : flags ;
 import errors : error ;
 import generate ;
 import generators ;
+import numbers ;
 import os ;
 import print ;
 import project ;
@@ -146,6 +147,33 @@ feature.feature warnings-as-errors :
     on         # Fail the compilation if there are warnings.
   : incidental propagated ;
 
+# Feature that allows us to configure the maximal template instantiation depth
+# level allowed by a C++ compiler. Applies only to C++ toolsets whose compilers
+# actually support this configuration setting.
+#
+# Note that Boost Build currently does not allow defining features that take any
+# positive integral value as a parameter, which is what we need here, so we just
+# define some of the values here and leave it up to the user to extend this set
+# as he needs using the feature.extend rule.
+#
+# If a specific toolset requires a default value for this feature other than the
+# one defined here it should set the feature's default value using the
+# feature.set-default rule.
+#
+# TODO: This should be upgraded as soon as Boost Build adds support for custom
+# validated feature values or at least features allowing any positive integral
+# value. See related Boost Build related trac ticket #194.
+#
+feature.feature c++-template-depth
+    :
+        [ numbers.range 128 1024 : 128 ]
+        [ numbers.range  20 1000 :  10 ]
+        #   Maximum template instantiation depth guaranteed for ANSI/ISO C++
+        # conforming programs.
+        17
+    :
+        incidental propagated ;
+
 feature.feature source              :            : free dependency incidental ;
 feature.feature library             :            : free dependency incidental ;
 feature.feature file                :            : free dependency incidental ;

src/tools/gcc.jam

@@ -345,6 +345,8 @@ flags gcc.compile USER_OPTIONS <cflags> ;
 flags gcc.compile.c++ USER_OPTIONS <cxxflags> ;
 flags gcc.compile DEFINES <define> ;
 flags gcc.compile INCLUDES <include> ;
+flags gcc.compile.c++ TEMPLATE_DEPTH <c++-template-depth> ;
+
 
 actions compile.c++.pch
 {
@@ -381,7 +383,7 @@ rule compile.c
 
 actions compile.c++ bind PCH_FILE
 {
-    "$(CONFIG_COMMAND)" $(LANG) -ftemplate-depth-128 $(OPTIONS) $(USER_OPTIONS) -D$(DEFINES) -I"$(PCH_FILE:D)" -I"$(INCLUDES)" -c -o "$(<:W)" "$(>:W)"
+    "$(CONFIG_COMMAND)" $(LANG) -ftemplate-depth-$(TEMPLATE_DEPTH) $(OPTIONS) $(USER_OPTIONS) -D$(DEFINES) -I"$(PCH_FILE:D)" -I"$(INCLUDES)" -c -o "$(<:W)" "$(>:W)"
 }
 
 actions compile.c bind PCH_FILE

src/tools/qcc.jam

@@ -79,10 +79,13 @@ flags qcc.compile INCLUDES <include> ;
 
 flags qcc.compile OPTIONS <link>shared : -shared ;
 
+flags qcc.compile.c++ TEMPLATE_DEPTH <c++-template-depth> ;
+feature.set-default c++-template-depth : 100 ;
+
 
 actions compile.c++
 {
-    "$(CONFIG_COMMAND)" -Wc,-ftemplate-depth-100 $(OPTIONS) -D$(DEFINES) -I"$(INCLUDES)" -c -o "$(<)" "$(>)"
+    "$(CONFIG_COMMAND)" -Wc,-ftemplate-depth-$(TEMPLATE_DEPTH) $(OPTIONS) -D$(DEFINES) -I"$(INCLUDES)" -c -o "$(<)" "$(>)"
 }
 
 actions compile.c