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document changes to mangling of type and identifier back refs #1664

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dlang-bot merged 1 commit into from
Sep 3, 2017
Merged

document changes to mangling of type and identifier back refs #1664

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88 changes: 71 additions & 17 deletions spec/abi.dd
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Original file line number Diff line number Diff line change
Expand Up @@ -205,31 +205,44 @@ $(H2 $(LNAME2 name_mangling, Name Mangling))
$(GRAMMAR
$(GNAME MangledName):
$(B _D) $(GLINK QualifiedName) $(GLINK Type)
$(B _D) $(GLINK QualifiedName) $(B M) $(GLINK Type)
$(B _D) $(GLINK QualifiedName) $(B Z) $(GREEN // Internal)
)

$(P The $(GLINK Type) above is the type of a variable or the return type of a function.
This is never a $(GLINK TypeFunction), as the latter can only be bound to a value via a pointer
to a function or a delegate.)

$(GRAMMAR
$(GNAME QualifiedName):
$(GLINK SymbolFunctionName)
$(GLINK SymbolFunctionName) $(I QualifiedName)

$(GNAME SymbolFunctionName):
$(GLINK SymbolName)
$(GLINK SymbolName) $(I QualifiedName)
$(GLINK SymbolName) $(GLINK TypeFunctionNoReturn) $(I QualifiedName)
$(GLINK SymbolName) $(B M) $(GLINK TypeModifiers)$(OPT) $(GLINK TypeFunctionNoReturn) $(I QualifiedName)
$(GLINK SymbolName) $(GLINK TypeFunctionNoReturn)
$(GLINK SymbolName) $(B M) $(GLINK TypeModifiers)$(OPT) $(GLINK TypeFunctionNoReturn)
)

$(P The $(B M) means that the symbol is a function that requires
a $(D this) pointer. Class or struct fields are mangled without $(B M).
To disambiguate $(B M) from being a $(GLINK Parameter) with modifier `scope`, the
following type needs to be checked for being a $(GLINK TypeFunction).)

$(GRAMMAR
$(GNAME SymbolName):
$(GLINK LName)
$(GLINK TemplateInstanceName)
$(B 0) $(GREEN // anonymous symbols)
$(GLINK IdentifierBackRef)
$(B 0) $(GREEN // anonymous symbols)
)

$(P The $(B M) means that the symbol is a function that requires
a $(D this) pointer.)

$(P Template Instance Names have the types and values of its parameters
encoded into it:
)

$(GRAMMAR
$(GNAME TemplateInstanceName):
$(GLINK Number) $(GLINK TemplateID) $(GLINK LName) $(GLINK TemplateArgs) $(B Z)
$(GLINK TemplateID) $(GLINK LName) $(GLINK TemplateArgs) $(B Z)

$(GNAME TemplateID):
$(B __T)
Expand All @@ -242,13 +255,23 @@ $(H2 $(LNAME2 name_mangling, Name Mangling))
$(GNAME TemplateArg):
$(GLINK TemplateArgX)
$(B H) $(GLINK TemplateArgX)
)
$(P If a template argument matches a specialized template parameter, the argument
is mangled with prefix $(B H).)

$(GRAMMAR
$(GNAME TemplateArgX):
$(B T) $(GLINK Type)
$(B V) $(GLINK Type) $(GLINK Value)
$(B S) $(GLINK Number) $(GLINK QualifiedName)
$(B S) $(GLINK Number) $(GLINK MangledName)
$(B S) $(GLINK QualifiedName)
$(B X) $(GLINK Number) $(I ExternallyMangledName)
)

$(P $(I ExternallyMangledName) can be any series of characters allowed on the
current platform, e.g. generated by functions with C++ linkage or annotated
with `pragma(mangle,...)`.)

$(GRAMMAR
$(GNAME Value):
$(B n)
$(B i) $(GLINK Number)
Expand Down Expand Up @@ -293,7 +316,7 @@ $(H2 $(LNAME2 name_mangling, Name Mangling))
$(DT $(B n))
$(DD is for $(B null) arguments.)

$(DT $(GLINK Number))
$(DT $(B i) $(GLINK Number))
$(DD is for positive numeric literals (including
character literals).)

Expand Down Expand Up @@ -343,7 +366,7 @@ $(H2 $(LNAME2 name_mangling, Name Mangling))
$(GLINK Namechar) $(I Namechars)
)

$(P A $(GLINK Name) is a standard D identifier.)
$(P A $(GLINK Name) is a standard D $(DDSUBLINK spec/lex, identifiers, identifier).)

$(GRAMMAR
$(GNAME LName):
Expand All @@ -370,13 +393,41 @@ $(H2 $(LNAME2 name_mangling, Name Mangling))
the number of characters in the $(GLINK Name).
)

$(H2 $(LNAME2 type_mangling, Type Mangling))
$(H3 $(LNAME2 back_ref, Back references))

$(P Any $(GLINK LName) or non-basic $(GLINK Type) (i.e. any type
that does not encode as a fixed one or two character sequence) that has been
emitted to the mangled symbol before will not be emitted again, but is referenced
by a special sequence encoding the relative position of the original occurrence in the mangled
symbol name.)

$(P Numbers in back references are encoded with base 26 by upper case letters $(B A) - $(B Z) for higher digits
but lower case letters $(B a) - $(B z) for the last digit.)

$(GRAMMAR
$(GNAME TypeBackRef):
$(B Q) $(GLINK NumberBackRef)

$(GNAME IdentifierBackRef):
$(B Q) $(GLINK NumberBackRef)

$(GNAME NumberTypeRef):
$(I lower-case-letter)
$(I upper-case-letter) $(GLINK NumberTypeRef)
)

$(P To distinguish between the type of the back reference a look-up of the back referenced character is necessary:
An identifier back reference always points to a digit $(B 0) to $(B 9), while a type back reference always points
to a letter.)

$(H3 $(LNAME2 type_mangling, Type Mangling))

$(P Types are mangled using a simple linear scheme:)

$(GRAMMAR
$(GNAME Type):
$(GLINK TypeModifiers)$(OPT) $(GLINK TypeX)
$(GLINK TypeBackRef)

$(GNAME TypeX):
$(GLINK TypeArray)
Expand Down Expand Up @@ -475,15 +526,18 @@ $(H2 $(LNAME2 type_mangling, Type Mangling))

$(GNAME FuncAttr):
$(GLINK FuncAttrPure)
$(GLINK FuncAttrNogc)
$(GLINK FuncAttrNothrow)
$(GLINK FuncAttrProperty)
$(GLINK FuncAttrRef)
$(GLINK FuncAttrProperty)
$(GLINK FuncAttrNogc)
$(GLINK FuncAttrReturn)
$(GLINK FuncAttrScope)
$(GLINK FuncAttrTrusted)
$(GLINK FuncAttrSafe)
)
$(P Function attributes are emitted in the order as listed above.)

$(GRAMMAR
$(GNAME FuncAttrPure):
$(B Na)

Expand Down Expand Up @@ -624,7 +678,7 @@ $(H2 $(LNAME2 type_mangling, Type Mangling))
$(B n)

$(GNAME TypeTuple):
$(B B) $(GLINK Number) $(GLINK Parameters)
$(B B) $(GLINK Parameters) $(B Z)
)

$(H2 $(LNAME2 function_calling_conventions, Function Calling Conventions))
Expand Down