Address markdown lint warnings. (#527)

* enable MD009

* fix MD009

No trailing spaces.

* 2nd pass fixing MD009, turn on MD010

* enable MD010

* Fix MD010, enable MD012

* Fix MD012

.markdownlint.json

@@ -12,9 +12,6 @@
         ]
     },
 
-    "MD009" : false,
-    "MD010" : false,
-    "MD012" : false,
     "MD022" : false,
     "MD027" : false,
     "MD028" : false,

README.md

@@ -35,7 +35,7 @@ This folder contains an ANTLR grammar-extraction tool and support files.
 
 - GetGrammar.bat - the Windows batch file that invokes ExtractGrammar on each md file of the C# specification that contains ANTLR grammar blocks, in clause order, inserting some md headers and such along the way. The result is a file called grammar.md, **which is a direct replacement for that file in the specification repo**.
 
-> A minor wart: There is an extraneous blank line at the beginning of each of the lexical, syntactic, and unsafe grammars. At a glance, the amount of programming effort probably needed to stop this from happening seems to be *huge* compared with simply deleting those three lines manually. 
+> A minor wart: There is an extraneous blank line at the beginning of each of the lexical, syntactic, and unsafe grammars. At a glance, the amount of programming effort probably needed to stop this from happening seems to be *huge* compared with simply deleting those three lines manually.
 
 ### MarkdownConverter
 

admin/guidelines-for-spec-writing-and-formatting.md

@@ -1,10 +1,10 @@
 # Guidelines to Spec Writing and Formatting
 
-1.	Put meta-information about the standard (e.g., what "implementation" means) in the Terms-and-definitions clause. C#-specific terms should be italicized on their first use only in the narrative.
-1.	Don't say the same thing normatively in more than one place; say it once and point to that place, as needed.
-1.	For requirements, use *shall* and *shall not*. Inside informative (that is, non-normative) text, **never** use *shall*, use *must* instead.
-1.	Examples and Notes marked as such are informative, and requirements *must* be clear *without* them. Ask yourself, "Does the normative text standalone if all the examples and notes are removed?"
-1.	While examples are good, keep them small, simple, and narrowly focused without using unnecessary features. A spec is *not* a tutorial!
-1.	Avoid using quoted text, as in "natural type." If that is a term, except for its first use it should be in regular font without the quotes. In general, such quote marks dilute the contents, especially if their use suggests, "sort of like this thingie." Rather than use an approximate description in quotes, choose the right term or other English text.
-1.	Use singular instead of plural: For example, don't say, "Tuple types are declared using the following syntax:"; instead, say, "A tuple type is declared using the following syntax:". For the most part, the plural form is quite clear, but there can be cases where it isn't, so it's best to use the singular form.
-1.	A section should contain either subsections or text, but never both. Consider the case in which we have a section with *no* subsections: ## Section S; some text. Later one or more subsections are added, resulting in ## Section S; some text; ### Subsection S.1; some text; ### Subsection S.2; some text. This is *bad*, as a subsequent reference to S is ambiguous; is it to that whole section or is it to the preamble text at the start of that section? As such, you need to put the preamble text in a new subsection (which we've called "General") at the start of that section.
+1. Put meta-information about the standard (e.g., what "implementation" means) in the Terms-and-definitions clause. C#-specific terms should be italicized on their first use only in the narrative.
+1. Don't say the same thing normatively in more than one place; say it once and point to that place, as needed.
+1. For requirements, use *shall* and *shall not*. Inside informative (that is, non-normative) text, **never** use *shall*, use *must* instead.
+1. Examples and Notes marked as such are informative, and requirements *must* be clear *without* them. Ask yourself, "Does the normative text standalone if all the examples and notes are removed?"
+1. While examples are good, keep them small, simple, and narrowly focused without using unnecessary features. A spec is *not* a tutorial!
+1. Avoid using quoted text, as in "natural type." If that is a term, except for its first use it should be in regular font without the quotes. In general, such quote marks dilute the contents, especially if their use suggests, "sort of like this thingie." Rather than use an approximate description in quotes, choose the right term or other English text.
+1. Use singular instead of plural: For example, don't say, "Tuple types are declared using the following syntax:"; instead, say, "A tuple type is declared using the following syntax:". For the most part, the plural form is quite clear, but there can be cases where it isn't, so it's best to use the singular form.
+1. A section should contain either subsections or text, but never both. Consider the case in which we have a section with *no* subsections: ## Section S; some text. Later one or more subsections are added, resulting in ## Section S; some text; ### Subsection S.1; some text; ### Subsection S.2; some text. This is *bad*, as a subsequent reference to S is ambiguous; is it to that whole section or is it to the preamble text at the start of that section? As such, you need to put the preamble text in a new subsection (which we've called "General") at the start of that section.

standard/arrays.md

@@ -43,7 +43,7 @@ In effect, the *rank_specifier*s are read from left to right *before* the final
 
 > *Example*: The type in `T[][,,][,]` is a single-dimensional array of three-dimensional arrays of two-dimensional arrays of `int`. *end example*
 
-At run-time, a value of an array type can be `null` or a reference to an instance of that array type. 
+At run-time, a value of an array type can be `null` or a reference to an instance of that array type.
 
 > *Note*: Following the rules of [§16.6](arrays.md#166-array-covariance), the value may also be a reference to a covariant array type. *end note*
 

standard/attributes.md

@@ -4,7 +4,7 @@
 
 Much of the C# language enables the programmer to specify declarative information about the entities defined in the program. For example, the accessibility of a method in a class is specified by decorating it with the *method_modifier*s `public`, `protected`, `internal`, and `private`.
 
-C# enables programmers to invent new kinds of declarative information, called ***attributes***. Programmers can then attach attributes to various program entities, and retrieve attribute information in a run-time environment. 
+C# enables programmers to invent new kinds of declarative information, called ***attributes***. Programmers can then attach attributes to various program entities, and retrieve attribute information in a run-time environment.
 
 > *Note*: For instance, a framework might define a `HelpAttribute` attribute that can be placed on certain program elements (such as classes and methods) to provide a mapping from those program elements to their documentation. *end note*
 
@@ -75,7 +75,7 @@ The attribute `AttributeUsage` ([§21.5.2](attributes.md#2152-the-attributeusage
 > }
 > ```
 > defines a multi-use attribute class named `AuthorAttribute`. The example
-> 
+>
 > ```csharp
 > [Author("Brian Kernighan"), Author("Dennis Ritchie")]
 > class Class1 
@@ -108,7 +108,7 @@ class X : Attribute { ... }
 
 ### 21.2.3 Positional and named parameters
 
-Attribute classes can have ***positional parameters*** and ***named parameters***. Each public instance constructor for an attribute class defines a valid sequence of positional parameters for that attribute class. Each non-static public read-write field and property for an attribute class defines a named parameter for the attribute class. For a property to define a named parameter, that property shall have both a public get accessor and a public set accessor.   
+Attribute classes can have ***positional parameters*** and ***named parameters***. Each public instance constructor for an attribute class defines a valid sequence of positional parameters for that attribute class. Each non-static public read-write field and property for an attribute class defines a named parameter for the attribute class. For a property to define a named parameter, that property shall have both a public get accessor and a public set accessor.
 
 > *Example*: The example
 > ```csharp
@@ -132,7 +132,7 @@ Attribute classes can have ***positional parameters*** and ***named parameters**
 > }
 > ```
 > defines an attribute class named `HelpAttribute` that has one positional parameter, `url`, and one named parameter, `Topic`. Although it is non-static and public, the property `Url` does not define a named parameter, since it is not read-write.
-> 
+>
 > This attribute class might be used as follows:
 > ```csharp
 > [Help("http://www.mycompany.com/.../Class1.htm")]
@@ -309,7 +309,8 @@ By convention, attribute classes are named with a suffix of `Attribute`. An *att
 - If the right-most identifier of the *attribute_name* is a verbatim identifier ([§6.4.3](lexical-structure.md#643-identifiers)), then the *attribute_name* is resolved as a *type_name* ([§7.8](basic-concepts.md#78-namespace-and-type-names)). If the result is not a type derived from `System.Attribute`, a compile-time error occurs.
 - Otherwise,
   - The *attribute_name* is resolved as a *type_name* ([§7.8](basic-concepts.md#78-namespace-and-type-names)) except any errors are suppressed. If this resolution is successful and results in a type derived from `System.Attribute` then the type is the result of this step.
-  - The characters `Attribute` are appended to the right-most identifier in the *attribute_name* and the resulting string of tokens is resolved as a *type_name* ([§7.8](basic-concepts.md#78-namespace-and-type-names)) except any errors are suppressed. If this resolution is successful and results in a type derived from `System.Attribute` then the type is the result of this step.      
+  - The characters `Attribute` are appended to the right-most identifier in the *attribute_name* and the resulting string of tokens is resolved as a *type_name* ([§7.8](basic-concepts.md#78-namespace-and-type-names)) except any errors are suppressed. If this resolution is successful and results in a type derived from `System.Attribute` then the type is the result of this step.
+
 If exactly one of the two steps above results in a type derived from `System.Attribute`, then that type is the result of the *attribute_name*. Otherwise a compile-time error occurs.
 
 *Example*: If an attribute class is found both with and without this suffix, an ambiguity is present, and a compile-time error results. If the *attribute_name* is spelled such that its right-most *identifier* is a verbatim identifier ([§6.4.3](lexical-structure.md#643-identifiers)), then only an attribute without a suffix is matched, thus enabling such an ambiguity to be resolved. The example
@@ -452,7 +453,7 @@ The compilation of an *attribute* with attribute class `T`, *positional_argumen
 - For each *named_argument* `Arg` in `N`:
   - Let `Name` be the *identifier* of the *named_argument* `Arg`.
   - `Name` shall identify a non-static read-write public field or property on `T`. If `T` has no such field or property, then a compile-time error occurs.
-- If any of the values within *positional_argument_list* `P` or one of the values within *named_argument_list* `N` is of type `System.String` and the value is not well-formed as defined by the Unicode Standard, it is implementation-defined whether the value compiled is equal to the run-time value retrieved ([§21.4.3](attributes.md#2143-run-time-retrieval-of-an-attribute-instance)). 
+- If any of the values within *positional_argument_list* `P` or one of the values within *named_argument_list* `N` is of type `System.String` and the value is not well-formed as defined by the Unicode Standard, it is implementation-defined whether the value compiled is equal to the run-time value retrieved ([§21.4.3](attributes.md#2143-run-time-retrieval-of-an-attribute-instance)).
   > *Note*: As an example, a string which contains a high surrogate UTF-16 code unit which isn’t immediately followed by a low surrogate code unit is not well-formed. *end note*
 - Store the following information (for run-time instantiation of the attribute) in the assembly output by the compiler as a result of compiling the program containing the attribute: the attribute class `T`, the instance constructor `C` on `T`, the *positional_argument_list * `P`, the *named_argument_list* `N`, and the associated program entity `E`, with the values resolved completely at compile-time.
 
@@ -505,9 +506,7 @@ A small number of attributes affect the language in some way. These attributes i
 - `System.AttributeUsageAttribute` ([§21.5.2](attributes.md#2152-the-attributeusage-attribute)), which is used to describe the ways in which an attribute class can be used.
 - `System.Diagnostics.ConditionalAttribute` ([§21.5.3](attributes.md#2153-the-conditional-attribute)), is a multi-use attribute class which is used to define conditional methods and conditional attribute classes. This attribute indicates a condition by testing a conditional compilation symbol.
 - `System.ObsoleteAttribute` ([§21.5.4](attributes.md#2154-the-obsolete-attribute)), which is used to mark a member as obsolete.
-- `System.Runtime.CompilerServices.CallerLineNumberAttribute` ([§21.5.5.2](attributes.md#21552-the-callerlinenumber-attribute)), 
-    `System.Runtime.CompilerServices.CallerFilePathAttribute` ([§21.5.5.3](attributes.md#21553-the-callerfilepath-attribute)), and 
-    `System.Runtime.CompilerServices.CallerMemberNameAttribute` ([§21.5.5.4](attributes.md#21554-the-callermembername-attribute)), which are used to supply information about the calling context to optional parameters.
+- `System.Runtime.CompilerServices.CallerLineNumberAttribute` ([§21.5.5.2](attributes.md#21552-the-callerlinenumber-attribute)), `System.Runtime.CompilerServices.CallerFilePathAttribute` ([§21.5.5.3](attributes.md#21553-the-callerfilepath-attribute)), and `System.Runtime.CompilerServices.CallerMemberNameAttribute` ([§21.5.5.4](attributes.md#21554-the-callermembername-attribute)), which are used to supply information about the calling context to optional parameters.
 
 An execution environment may provide additional implementation-specific attributes that affect the execution of a C# program.
 
@@ -810,7 +809,7 @@ For invocations that occur within declarations of instance constructors, static
 ## 21.6 Attributes for interoperation
 
 For interoperation with other languages, an indexer may be implemented using indexed properties. If no `IndexerName` attribute is present for an indexer, then the name `Item` is used by default. The `IndexerName` attribute enables a developer to override this default and specify a different name.
-   
+
 > *Example*: By default, an indexer’s name is `Item`. This can be overridden, as follows:
 > ```csharp
 > [System.Runtime.CompilerServices.IndexerName("TheItem")]