Merge pull request #2001 from wilzbach/1040-more

Revive #1040 - spec/{enum,expression}.d + dcompiler.d
merged-on-behalf-of: Sebastian Wilzbach <sebi.wilzbach@gmail.com>

Author: dlang-bot

dcompiler.dd

@@ -885,7 +885,7 @@ dmd -cov -unittest myprog.d
         $(D unittest) $(LINK2 spec/version.html#PredefinedVersions, version identifier)
       )
       $(SWITCH $(SWNAME -v),
-        verbose
+        enable verbose output for each compiler pass
       )
       $(SWITCH $(SWNAME -vcolumns),
         print character (column) numbers in diagnostics

spec/enum.dd

@@ -260,6 +260,27 @@ enum size = __traits(classInstanceSize, Foo);  // evaluated at compile-time
 	$(P Using manifest constants is an idiomatic D method
 	to force compile-time evaluation of an expression.)
 
+---
+template Foo(T)
+{
+    // Not bad, but the 'size' variable will be located in the executable.
+    const size_t size = T.sizeof;       // evaluated at compile-time
+
+    // ... use of 'size' at compile time ...
+}
+
+template Bar(T)
+{
+    // Better, the manifest constant has no runtime location in the executable.
+    enum size_t size = T.sizeof;        // evaluated at compile-time
+
+    // ... use of 'size' at compile time ...
+
+    // If you take the address of Foo!T.size, it would also go into exe file.
+    auto p = &Foo!T.size;
+}
+---
+
 
 $(SPEC_SUBNAV_PREV_NEXT interface, Interfaces, const3, Type Qualifiers)
 )

spec/expression.dd

@@ -1654,16 +1654,6 @@ $(GNAME AssertExpression):
         Contract Programming) support in D.
     )
 
-    $(P The expression $(D assert(0)) is a special case; it
-        signifies that it is unreachable code.
-        Either $(D AssertError) is thrown at runtime if it is reachable,
-        or the execution is halted
-        (on the x86 processor, a $(D HLT) instruction can be used to halt
-        execution).
-        The optimization and code generation phases of compilation may
-        assume that it is unreachable code.
-    )
-
     $(P The second $(I AssignExpression), if present, must be implicitly
         convertible to type $(D const(char)[]).
         It is evaluated if the
@@ -1680,9 +1670,20 @@ $(GNAME AssertExpression):
     $(P When compiled and run, it will produce the message:)
 
 $(CONSOLE
-Error: AssertError Failure test.d(3) an error message
+core.exception.AssertError@test.d(3) an error message
 )
 
+    $(P The expression $(D assert(0)) is a special case; it
+        signifies that it is unreachable code.
+        Without optimizations, an $(D AssertError) is thrown at runtime.
+        In release mode ($(LINK2 $(ROOT_DIR)/dmd.html#switch-release, `-release`))
+        the execution is halted
+        (on the x86 processor, a $(D HLT) instruction can be used to halt
+        execution).
+        The optimization and code generation phases of compilation may
+        assume that it is unreachable code.
+    )
+
 $(H3 $(LNAME2 mixin_expressions, Mixin Expressions))
 
 $(GRAMMAR